- 21 Feb, 2022 22 commits
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Jason A. Donenfeld authored
With tools like kbench9000 giving more finegrained responses, and this basically never having been used ever since it was initially added, let's just get rid of this. There *is* still work to be done on the interrupt handler, but this really isn't the way it's being developed. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
Eric Biggers <ebiggers@google.com> Reviewed-by:
Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by:
Jason A. Donenfeld <Jason@zx2c4.com>
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Jason A. Donenfeld authored
Now that we have an explicit base_crng generation counter, we don't need a separate one for batched entropy. Rather, we can just move the generation forward every time we change crng_init state or update the base_crng key. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Dominik Brodowski authored
crng_init is protected by primary_crng->lock. Therefore, we need to hold this lock when increasing crng_init to 2. As we shouldn't hold this lock for too long, only hold it for those parts which require protection. Signed-off-by:
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Jason A. Donenfeld authored
This buffer may contain entropic data that shouldn't stick around longer than needed, so zero out the temporary buffer at the end of write_pool(). Reviewed-by:
Jann Horn <jannh@google.com> Reviewed-by:
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Jason A. Donenfeld authored
In 79a84687 ("random: check for increase of entropy_count because of signed conversion"), a number of checks were added around what values were passed to account(), because account() was doing fancy fixed point fractional arithmetic, and a user had some ability to pass large values directly into it. One of things in that commit was limiting those values to INT_MAX >> 6. The first >> 3 was for bytes to bits, and the next >> 3 was for bits to 1/8 fractional bits. However, for several years now, urandom reads no longer touch entropy accounting, and so this check serves no purpose. The current flow is: urandom_read_nowarn()-->get_random_bytes_user()-->chacha20_block() Of course, we don't want that size_t to be truncated when adding it into the ssize_t. But we arrive at urandom_read_nowarn() in the first place either via ordinary fops, which limits reads to MAX_RW_COUNT, or via getrandom() which limits reads to INT_MAX. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
We've been using a flurry of int, unsigned int, size_t, and ssize_t. Let's unify all of this into size_t where it makes sense, as it does in most places, and leave ssize_t for return values with possible errors. In addition, keeping with the convention of other functions in this file, functions that are dealing with raw bytes now take void * consistently instead of a mix of that and u8 *, because much of the time we're actually passing some other structure that is then interpreted as bytes by the function. We also take the opportunity to fix the outdated and incorrect comment in get_random_bytes_arch(). Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
Since we have a hash function that's really fast, and the goal of crng_slow_load() is reportedly to "touch all of the crng's state", we can just hash the old state together with the new state and call it a day. This way we dont need to reason about another LFSR or worry about various attacks there. This code is only ever used at early boot and then never again. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
Rather than the clunky NUMA full ChaCha state system we had prior, this commit is closer to the original "fast key erasure RNG" proposal from <https://blog.cr.yp.to/20170723-random.html>, by simply treating ChaCha keys on a per-cpu basis. All entropy is extracted to a base crng key of 32 bytes. This base crng has a birthdate and a generation counter. When we go to take bytes from the crng, we first check if the birthdate is too old; if it is, we reseed per usual. Then we start working on a per-cpu crng. This per-cpu crng makes sure that it has the same generation counter as the base crng. If it doesn't, it does fast key erasure with the base crng key and uses the output as its new per-cpu key, and then updates its local generation counter. Then, using this per-cpu state, we do ordinary fast key erasure. Half of this first block is used to overwrite the per-cpu crng key for the next call -- this is the fast key erasure RNG idea -- and the other half, along with the ChaCha state, is returned to the caller. If the caller desires more than this remaining half, it can generate more ChaCha blocks, unlocked, using the now detached ChaCha state that was just returned. Crypto-wise, this is more or less what we were doing before, but this simply makes it more explicit and ensures that we always have backtrack protection by not playing games with a shared block counter. The flow looks like this: ──extract()──► base_crng.key ◄──memcpy()───┐ │ │ └──chacha()──────┬─► new_base_key └─► crngs[n].key ◄──memcpy()───┐ │ │ └──chacha()───┬─► new_key └─► random_bytes │ └────► There are a few hairy details around early init. Just as was done before, prior to having gathered enough entropy, crng_fast_load() and crng_slow_load() dump bytes directly into the base crng, and when we go to take bytes from the crng, in that case, we're doing fast key erasure with the base crng rather than the fast unlocked per-cpu crngs. This is fine as that's only the state of affairs during very early boot; once the crng initializes we never use these paths again. In the process of all this, the APIs into the crng become a bit simpler: we have get_random_bytes(buf, len) and get_random_bytes_user(buf, len), which both do what you'd expect. All of the details of fast key erasure and per-cpu selection happen only in a very short critical section of crng_make_state(), which selects the right per-cpu key, does the fast key erasure, and returns a local state to the caller's stack. So, we no longer have a need for a separate backtrack function, as this happens all at once here. The API then allows us to extend backtrack protection to batched entropy without really having to do much at all. The result is a bit simpler than before and has fewer foot guns. The init time state machine also gets a lot simpler as we don't need to wait for workqueues to come online and do deferred work. And the multi-core performance should be increased significantly, by virtue of having hardly any locking on the fast path. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by:
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Jason A. Donenfeld authored
During crng_init == 0, we never credit entropy in add_interrupt_ randomness(), but instead dump it directly into the primary_crng. That's fine, except for the fact that we then wind up throwing away that entropy later when we switch to extracting from the input pool and xoring into (and later in this series overwriting) the primary_crng key. The two other early init sites -- add_hwgenerator_randomness()'s use crng_fast_load() and add_device_ randomness()'s use of crng_slow_load() -- always additionally give their inputs to the input pool. But not add_interrupt_randomness(). This commit fixes that shortcoming by calling mix_pool_bytes() after crng_fast_load() in add_interrupt_randomness(). That's partially verboten on PREEMPT_RT, where it implies taking spinlock_t from an IRQ handler. But this also only happens during early boot and then never again after that. Plus it's a trylock so it has the same considerations as calling crng_fast_load(), which we're already using. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
Continuing the reasoning of "random: ensure early RDSEED goes through mixer on init", we don't want RDRAND interacting with anything without going through the mixer function, as a backdoored CPU could presumably cancel out data during an xor, which it'd have a harder time doing when being forced through a cryptographic hash function. There's actually no need at all to be calling RDRAND in write_pool(), because before we extract from the pool, we always do so with 32 bytes of RDSEED hashed in at that stage. Xoring at this stage is needless and introduces a minor liability. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
Continuing the reasoning of "random: use RDSEED instead of RDRAND in entropy extraction" from this series, at init time we also don't want to be xoring RDSEED directly into the crng. Instead it's safer to put it into our entropy collector and then re-extract it, so that it goes through a hash function with preimage resistance. As a matter of hygiene, we also order these now so that the RDSEED byte are hashed in first, followed by the bytes that are likely more predictable (e.g. utsname()). Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
This is a preparatory commit for the following one. We simply inline the various functions that rand_initialize() calls that have no other callers. The compiler was doing this anyway before. Doing this will allow us to reorganize this after. We can then move the trust_cpu and parse_trust_cpu definitions a bit closer to where they're actually used, which makes the code easier to read. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
As the comment said, this is indeed a "hack". Since it was introduced, it's been a constant state machine nightmare, with lots of subtle early boot issues and a wildly complex set of machinery to keep everything in sync. Rather than continuing to play whack-a-mole with this approach, this commit simply removes it entirely. This commit is preparation for "random: use simpler fast key erasure flow on per-cpu keys" in this series, which introduces a simpler (and faster) mechanism to accomplish the same thing. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Jason A. Donenfeld authored
When /dev/random was directly connected with entropy extraction, without any expansion stage, extract_buf() was called for every 10 bytes of data read from /dev/random. For that reason, RDRAND was used rather than RDSEED. At the same time, crng_reseed() was still only called every 5 minutes, so there RDSEED made sense. Those olden days were also a time when the entropy collector did not use a cryptographic hash function, which meant most bets were off in terms of real preimage resistance. For that reason too it didn't matter _that_ much whether RDSEED was mixed in before or after entropy extraction; both choices were sort of bad. But now we have a cryptographic hash function at work, and with that we get real preimage resistance. We also now only call extract_entropy() every 5 minutes, rather than every 10 bytes. This allows us to do two important things. First, we can switch to using RDSEED in extract_entropy(), as Dominik suggested. Second, we can ensure that RDSEED input always goes into the cryptographic hash function with other things before being used directly. This eliminates a category of attacks in which the CPU knows the current state of the crng and knows that we're going to xor RDSEED into it, and so it computes a malicious RDSEED. By going through our hash function, it would require the CPU to compute a preimage on the fly, which isn't going to happen. Cc: Theodore Ts'o <tytso@mit.edu> Reviewed-by:
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Dominik Brodowski authored
crng_init is protected by primary_crng->lock, so keep holding that lock when incrementing crng_init from 0 to 1 in crng_fast_load(). The call to pr_notice() can wait until the lock is released; this code path cannot be reached twice, as crng_fast_load() aborts early if crng_init > 0. Signed-off-by:
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Jason A. Donenfeld authored
Rather than use spinlocks to protect batched entropy, we can instead disable interrupts locally, since we're dealing with per-cpu data, and manage resets with a basic generation counter. At the same time, we can't quite do this on PREEMPT_RT, where we still want spinlocks-as- mutexes semantics. So we use a local_lock_t, which provides the right behavior for each. Because this is a per-cpu lock, that generation counter is still doing the necessary CPU-to-CPU communication. This should improve performance a bit. It will also fix the linked splat that Jonathan received with a PROVE_RAW_LOCK_NESTING=y. Reviewed-by:
Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by:
Andy Lutomirski <luto@kernel.org> Reported-by:
Jonathan Neuschäfer <j.neuschaefer@gmx.net> Tested-by:
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Eric Biggers authored
The primary_crng is always reseeded from the input_pool, while the NUMA crngs are always reseeded from the primary_crng. Remove the redundant 'use_input_pool' parameter from crng_reseed() and just directly check whether the crng is the primary_crng. Signed-off-by:
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Jason A. Donenfeld authored
This is called from various hwgenerator drivers, so rather than having one "safe" version for userspace and one "unsafe" version for the kernel, just make everything safe; the checks are cheap and sensible to have anyway. Reported-by:
Sultan Alsawaf <sultan@kerneltoast.com> Reviewed-by:
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Jason A. Donenfeld authored
Now that POOL_BITS == POOL_MIN_BITS, we must unconditionally wake up entropy writers after every extraction. Therefore there's no point of write_wakeup_threshold, so we can move it to the dustbin of unused compatibility sysctls. While we're at it, we can fix a small comparison where we were waking up after <= min rather than < min. Cc: Theodore Ts'o <tytso@mit.edu> Suggested-by:
Eric Biggers <ebiggers@kernel.org> Reviewed-by:
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Jason A. Donenfeld authored
30e37ec5 ("random: account for entropy loss due to overwrites") assumed that adding new entropy to the LFSR pool probabilistically cancelled out old entropy there, so entropy was credited asymptotically, approximating Shannon entropy of independent sources (rather than a stronger min-entropy notion) using 1/8th fractional bits and replacing a constant 2-2/√𝑒 term (~0.786938) with 3/4 (0.75) to slightly underestimate it. This wasn't superb, but it was perhaps better than nothing, so that's what was done. Which entropy specifically was being cancelled out and how much precisely each time is hard to tell, though as I showed with the attack code in my previous commit, a motivated adversary with sufficient information can actually cancel out everything. Since we're no longer using an LFSR for entropy accumulation, this probabilistic cancellation is no longer relevant. Rather, we're now using a computational hash function as the accumulator and we've switched to working in the random oracle model, from which we can now revisit the question of min-entropy accumulation, which is done in detail in <https://eprint.iacr.org/2019/198>. Consider a long input bit string that is built by concatenating various smaller independent input bit strings. Each one of these inputs has a designated min-entropy, which is what we're passing to credit_entropy_bits(h). When we pass the concatenation of these to a random oracle, it means that an adversary trying to receive back the same reply as us would need to become certain about each part of the concatenated bit string we passed in, which means becoming certain about all of those h values. That means we can estimate the accumulation by simply adding up the h values in calls to credit_entropy_bits(h); there's no probabilistic cancellation at play like there was said to be for the LFSR. Incidentally, this is also what other entropy accumulators based on computational hash functions do as well. So this commit replaces credit_entropy_bits(h) with essentially `total = min(POOL_BITS, total + h)`, done with a cmpxchg loop as before. What if we're wrong and the above is nonsense? It's not, but let's assume we don't want the actual _behavior_ of the code to change much. Currently that behavior is not extracting from the input pool until it has 128 bits of entropy in it. With the old algorithm, we'd hit that magic 128 number after roughly 256 calls to credit_entropy_bits(1). So, we can retain more or less the old behavior by waiting to extract from the input pool until it hits 256 bits of entropy using the new code. For people concerned about this change, it means that there's not that much practical behavioral change. And for folks actually trying to model the behavior rigorously, it means that we have an even higher margin against attacks. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by:
Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com> Signed-off-by:
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Jason A. Donenfeld authored
Our pool is 256 bits, and we only ever use all of it or don't use it at all, which is decided by whether or not it has at least 128 bits in it. So we can drastically simplify the accounting and cmpxchg loop to do exactly this. While we're at it, we move the minimum bit size into a constant so it can be shared between the two places where it matters. The reason we want any of this is for the case in which an attacker has compromised the current state, and then bruteforces small amounts of entropy added to it. By demanding a particular minimum amount of entropy be present before reseeding, we make that bruteforcing difficult. Note that this rationale no longer includes anything about /dev/random blocking at the right moment, since /dev/random no longer blocks (except for at ~boot), but rather uses the crng. In a former life, /dev/random was different and therefore required a more nuanced account(), but this is no longer. Behaviorally, nothing changes here. This is just a simplification of the code. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by:
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Jason A. Donenfeld authored
The current 4096-bit LFSR used for entropy collection had a few desirable attributes for the context in which it was created. For example, the state was huge, which meant that /dev/random would be able to output quite a bit of accumulated entropy before blocking. It was also, in its time, quite fast at accumulating entropy byte-by-byte, which matters given the varying contexts in which mix_pool_bytes() is called. And its diffusion was relatively high, which meant that changes would ripple across several words of state rather quickly. However, it also suffers from a few security vulnerabilities. In particular, inputs learned by an attacker can be undone, but moreover, if the state of the pool leaks, its contents can be controlled and entirely zeroed out. I've demonstrated this attack with this SMT2 script, <https://xn--4db.cc/5o9xO8pb>, which Boolector/CaDiCal solves in a matter of seconds on a single core of my laptop, resulting in little proof of concept C demonstrators such as <https://xn--4db.cc/jCkvvIaH/c>. For basically all recent formal models of RNGs, these attacks represent a significant cryptographic flaw. But how does this manifest practically? If an attacker has access to the system to such a degree that he can learn the internal state of the RNG, arguably there are other lower hanging vulnerabilities -- side-channel, infoleak, or otherwise -- that might have higher priority. On the other hand, seed files are frequently used on systems that have a hard time generating much entropy on their own, and these seed files, being files, often leak or are duplicated and distributed accidentally, or are even seeded over the Internet intentionally, where their contents might be recorded or tampered with. Seen this way, an otherwise quasi-implausible vulnerability is a bit more practical than initially thought. Another aspect of the current mix_pool_bytes() function is that, while its performance was arguably competitive for the time in which it was created, it's no longer considered so. This patch improves performance significantly: on a high-end CPU, an i7-11850H, it improves performance of mix_pool_bytes() by 225%, and on a low-end CPU, a Cortex-A7, it improves performance by 103%. This commit replaces the LFSR of mix_pool_bytes() with a straight- forward cryptographic hash function, BLAKE2s, which is already in use for pool extraction. Universal hashing with a secret seed was considered too, something along the lines of <https://eprint.iacr.org/2013/338>, but the requirement for a secret seed makes for a chicken & egg problem. Instead we go with a formally proven scheme using a computational hash function, described in sections 5.1, 6.4, and B.1.8 of <https://eprint.iacr.org/2019/198>. BLAKE2s outputs 256 bits, which should give us an appropriate amount of min-entropy accumulation, and a wide enough margin of collision resistance against active attacks. mix_pool_bytes() becomes a simple call to blake2s_update(), for accumulation, while the extraction step becomes a blake2s_final() to generate a seed, with which we can then do a HKDF-like or BLAKE2X-like expansion, the first part of which we fold back as an init key for subsequent blake2s_update()s, and the rest we produce to the caller. This then is provided to our CRNG like usual. In that expansion step, we make opportunistic use of 32 bytes of RDRAND output, just as before. We also always reseed the crng with 32 bytes, unconditionally, or not at all, rather than sometimes with 16 as before, as we don't win anything by limiting beyond the 16 byte threshold. Going for a hash function as an entropy collector is a conservative, proven approach. The result of all this is a much simpler and much less bespoke construction than what's there now, which not only plugs a vulnerability but also improves performance considerably. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Reviewed-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by:
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- 20 Feb, 2022 13 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull locking fix from Borislav Petkov: "Fix a NULL ptr dereference when dumping lockdep chains through /proc/lockdep_chains" * tag 'locking_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: lockdep: Correct lock_classes index mapping
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 fixes from Borislav Petkov: - Fix the ptrace regset xfpregs_set() callback to behave according to the ABI - Handle poisoned pages properly in the SGX reclaimer code * tag 'x86_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/ptrace: Fix xfpregs_set()'s incorrect xmm clearing x86/sgx: Fix missing poison handling in reclaimer
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull scheduler fix from Borislav Petkov: "Fix task exposure order when forking tasks" * tag 'sched_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Fix yet more sched_fork() races
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git://git.kernel.org/pub/scm/linux/kernel/git/ras/rasLinus Torvalds authored
Pull EDAC fix from Borislav Petkov: "Fix a long-standing struct alignment bug in the EDAC struct allocation code" * tag 'edac_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras: EDAC: Fix calculation of returned address and next offset in edac_align_ptr()
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git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsiLinus Torvalds authored
Pull SCSI fixes from James Bottomley: "Three fixes, all in drivers. The ufs and qedi fixes are minor; the lpfc one is a bit bigger because it involves adding a heuristic to detect and deal with common but not standards compliant behaviour" * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: scsi: ufs: core: Fix divide by zero in ufshcd_map_queues() scsi: lpfc: Fix pt2pt NVMe PRLI reject LOGO loop scsi: qedi: Fix ABBA deadlock in qedi_process_tmf_resp() and qedi_process_cmd_cleanup_resp()
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git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/dmaengineLinus Torvalds authored
Pull dmaengine fixes from Vinod Koul: "A bunch of driver fixes for: - ptdma error handling in init - lock fix in at_hdmac - error path and error num fix for sh dma - pm balance fix for stm32" * tag 'dmaengine-fix-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/dmaengine: dmaengine: shdma: Fix runtime PM imbalance on error dmaengine: sh: rcar-dmac: Check for error num after dma_set_max_seg_size dmaengine: stm32-dmamux: Fix PM disable depth imbalance in stm32_dmamux_probe dmaengine: sh: rcar-dmac: Check for error num after setting mask dmaengine: at_xdmac: Fix missing unlock in at_xdmac_tasklet() dmaengine: ptdma: Fix the error handling path in pt_core_init()
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git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linuxLinus Torvalds authored
Pull i2c fixes from Wolfram Sang: "Some driver updates, a MAINTAINERS fix, and additions to COMPILE_TEST (so we won't miss build problems again)" * 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: MAINTAINERS: remove duplicate entry for i2c-qcom-geni i2c: brcmstb: fix support for DSL and CM variants i2c: qup: allow COMPILE_TEST i2c: imx: allow COMPILE_TEST i2c: cadence: allow COMPILE_TEST i2c: qcom-cci: don't put a device tree node before i2c_add_adapter() i2c: qcom-cci: don't delete an unregistered adapter i2c: bcm2835: Avoid clock stretching timeouts
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git://git.kernel.org/pub/scm/linux/kernel/git/dtor/inputLinus Torvalds authored
Pull input fixes from Dmitry Torokhov: - a fix for Synaptics touchpads in RMI4 mode failing to suspend/resume properly because I2C client devices are now being suspended and resumed asynchronously which changed the ordering - a change to make sure we do not set right and middle buttons capabilities on touchpads that are "buttonpads" (i.e. do not have separate physical buttons) - a change to zinitix touchscreen driver adding more compatible strings/IDs * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: Input: psmouse - set up dependency between PS/2 and SMBus companions Input: zinitix - add new compatible strings Input: clear BTN_RIGHT/MIDDLE on buttonpads
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git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supplyLinus Torvalds authored
Pull power supply fixes from Sebastian Reichel: "Three regression fixes for the 5.17 cycle: - build warning fix for power-supply documentation - pointer size fix in cw2015 battery driver - OOM handling in bq256xx charger driver" * tag 'for-v5.17-rc' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply: power: supply: bq256xx: Handle OOM correctly power: supply: core: fix application of sizeof to pointer power: supply: fix table problem in sysfs-class-power
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Linus Torvalds authored
Merge tag 'fs.mount_setattr.v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull mount_setattr test/doc fixes from Christian Brauner: "This contains a fix for one of the selftests for the mount_setattr syscall to create idmapped mounts, an entry for idmapped mounts for maintainers, and missing kernel documentation for the helper we split out some time ago to get and yield write access to a mount when changing mount properties" * tag 'fs.mount_setattr.v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: fs: add kernel doc for mnt_{hold,unhold}_writers() MAINTAINERS: add entry for idmapped mounts tests: fix idmapped mount_setattr test
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git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linuxLinus Torvalds authored
Pull pidfd fix from Christian Brauner: "This fixes a problem reported by lockdep when installing a pidfd via fd_install() with siglock and the tasklisk write lock held in copy_process() when calling clone()/clone3() with CLONE_PIDFD. Originally a pidfd was created prior to holding any of these locks but this required a call to ksys_close(). So quite some time ago in 6fd2fe49 ("copy_process(): don't use ksys_close() on cleanups") we switched to a get_unused_fd_flags() + fd_install() model. As part of that we moved fd_install() as late as possible. This was done for two main reasons. First, because we needed to ensure that we call fd_install() past the point of no return as once that's called the fd is live in the task's file table. Second, because we tried to ensure that the fd is visible in /proc/<pid>/fd/<pidfd> right when the task is visible. This fix moves the fd_install() to an even later point which means that a task will be visible in proc while the pidfd isn't yet under /proc/<pid>/fd/<pidfd>. While this is a user visible change it's very unlikely that this will have any impact. Nobody should be relying on that and if they do we need to come up with something better but again, it's doubtful this is relevant" * tag 'pidfd.v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: copy_process(): Move fd_install() out of sighand->siglock critical section
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Linus Torvalds authored
Merge branch 'ucount-rlimit-fixes-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull ucounts fixes from Eric Biederman: "Michal Koutný recently found some bugs in the enforcement of RLIMIT_NPROC in the recent ucount rlimit implementation. In this set of patches I have developed a very conservative approach changing only what is necessary to fix the bugs that I can see clearly. Cleanups and anything that is making the code more consistent can follow after we have the code working as it has historically. The problem is not so much inconsistencies (although those exist) but that it is very difficult to figure out what the code should be doing in the case of RLIMIT_NPROC. All other rlimits are only enforced where the resource is acquired (allocated). RLIMIT_NPROC by necessity needs to be enforced in an additional location, and our current implementation stumbled it's way into that implementation" * 'ucount-rlimit-fixes-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: ucounts: Handle wrapping in is_ucounts_overlimit ucounts: Move RLIMIT_NPROC handling after set_user ucounts: Base set_cred_ucounts changes on the real user ucounts: Enforce RLIMIT_NPROC not RLIMIT_NPROC+1 rlimit: Fix RLIMIT_NPROC enforcement failure caused by capability calls in set_user
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- 19 Feb, 2022 5 commits
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Wolfram Sang authored
The driver is already covered in the ARM/QUALCOMM section. Also, Akash Asthana's email bounces meanwhile and Mukesh Savaliya has never responded to mails regarding this driver. Signed-off-by:
Wolfram Sang <wsa@kernel.org> Acked-by:
Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by:
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Peter Zijlstra authored
Where commit 4ef0c5c6 ("kernel/sched: Fix sched_fork() access an invalid sched_task_group") fixed a fork race vs cgroup, it opened up a race vs syscalls by not placing the task on the runqueue before it gets exposed through the pidhash. Commit 13765de8 ("sched/fair: Fix fault in reweight_entity") is trying to fix a single instance of this, instead fix the whole class of issues, effectively reverting this commit. Fixes: 4ef0c5c6 ("kernel/sched: Fix sched_fork() access an invalid sched_task_group") Reported-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by:
Tadeusz Struk <tadeusz.struk@linaro.org> Tested-by:
Zhang Qiao <zhangqiao22@huawei.com> Tested-by:
Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/YgoeCbwj5mbCR0qA@hirez.programming.kicks-ass.net
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git://git.linux-nfs.org/projects/anna/linux-nfsLinus Torvalds authored
Pull NFS client bugfixes from Anna Schumaker: - Fix unnecessary changeattr revalidations - Fix resolving symlinks during directory lookups - Don't report writeback errors in nfs_getattr() * tag 'nfs-for-5.17-3' of git://git.linux-nfs.org/projects/anna/linux-nfs: NFS: Do not report writeback errors in nfs_getattr() NFS: LOOKUP_DIRECTORY is also ok with symlinks NFS: Remove an incorrect revalidation in nfs4_update_changeattr_locked()
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pmLinus Torvalds authored
Pull ACPI fixes from Rafael Wysocki: "These make an excess warning message go away and fix a recently introduced boot failure on a vintage machine. Specifics: - Change the log level of the "table not found" message in acpi_table_parse_entries_array() to debug to prevent it from showing up in the logs unnecessarily (Dan Williams) - Add a C-state limit quirk for 32-bit ThinkPad T40 to prevent it from crashing on boot after recent changes in the ACPI processor driver (Woody Suwalski)" * tag 'acpi-5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: ACPI: processor: idle: fix lockup regression on 32-bit ThinkPad T40 ACPI: tables: Quiet ACPI table not found warning -
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linuxLinus Torvalds authored
Pull RISC-V fixes from Palmer Dabbelt: "A set of three fixes, all aimed at fixing some fallout from the recent sparse hart ID support" * tag 'riscv-for-linus-5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: RISC-V: Fix IPI/RFENCE hmask on non-monotonic hartid ordering RISC-V: Fix handling of empty cpu masks RISC-V: Fix hartid mask handling for hartid 31 and up
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