- 14 Feb, 2015 40 commits
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Andrey Ryabinin authored
This feature let us to detect accesses out of bounds of global variables. This will work as for globals in kernel image, so for globals in modules. Currently this won't work for symbols in user-specified sections (e.g. __init, __read_mostly, ...) The idea of this is simple. Compiler increases each global variable by redzone size and add constructors invoking __asan_register_globals() function. Information about global variable (address, size, size with redzone ...) passed to __asan_register_globals() so we could poison variable's redzone. This patch also forces module_alloc() to return 8*PAGE_SIZE aligned address making shadow memory handling ( kasan_module_alloc()/kasan_module_free() ) more simple. Such alignment guarantees that each shadow page backing modules address space correspond to only one module_alloc() allocation. Signed-off-by:
Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by:
Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Andrey Ryabinin authored
MODULE_DEVICE_TABLE() macro used to create aliases to device tables. Normally alias should have the same type as aliased symbol. Device tables are arrays, so they have 'struct type##_device_id[x]' types. Alias created by MODULE_DEVICE_TABLE() will have non-array type - 'struct type##_device_id'. This inconsistency confuses compiler, it could make a wrong assumption about variable's size which leads KASan to produce a false positive report about out of bounds access. For every global variable compiler calls __asan_register_globals() passing information about global variable (address, size, size with redzone, name ...) __asan_register_globals() poison symbols redzone to detect possible out of bounds accesses. When symbol has an alias __asan_register_globals() will be called as for symbol so for alias. Compiler determines size of variable by size of variable's type. Alias and symbol have the same address, so if alias have the wrong size part of memory that actually belongs to the symbol could be poisoned as redzone of alias symbol. By fixing type of alias symbol we will fix size of it, so __asan_register_globals() will not poison valid memory. Signed-off-by:
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Andrey Ryabinin authored
KASan uses constructors for initializing redzones for global variables. Globals instrumentation in GCC 4.9.2 produces constructors with priority (.init_array.00099) Currently kernel ignores such constructors. Only constructors with default priority supported (.init_array) This patch adds support for constructors with priorities. For kernel image we put pointers to constructors between __ctors_start/__ctors_end and do_ctors() will call them on start up. For modules we merge .init_array.* sections into resulting .init_array. Module code properly handles constructors in .init_array section. Signed-off-by:
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Andrey Ryabinin authored
For instrumenting global variables KASan will shadow memory backing memory for modules. So on module loading we will need to allocate memory for shadow and map it at address in shadow that corresponds to the address allocated in module_alloc(). __vmalloc_node_range() could be used for this purpose, except it puts a guard hole after allocated area. Guard hole in shadow memory should be a problem because at some future point we might need to have a shadow memory at address occupied by guard hole. So we could fail to allocate shadow for module_alloc(). Now we have VM_NO_GUARD flag disabling guard page, so we need to pass into __vmalloc_node_range(). Add new parameter 'vm_flags' to __vmalloc_node_range() function. Signed-off-by:
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Andrey Ryabinin authored
For instrumenting global variables KASan will shadow memory backing memory for modules. So on module loading we will need to allocate memory for shadow and map it at address in shadow that corresponds to the address allocated in module_alloc(). __vmalloc_node_range() could be used for this purpose, except it puts a guard hole after allocated area. Guard hole in shadow memory should be a problem because at some future point we might need to have a shadow memory at address occupied by guard hole. So we could fail to allocate shadow for module_alloc(). Add a new vm_struct flag 'VM_NO_GUARD' indicating that vm area doesn't have a guard hole. Signed-off-by:
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Andrey Ryabinin authored
Stack instrumentation allows to detect out of bounds memory accesses for variables allocated on stack. Compiler adds redzones around every variable on stack and poisons redzones in function's prologue. Such approach significantly increases stack usage, so all in-kernel stacks size were doubled. Signed-off-by:
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Andrey Ryabinin authored
Recently instrumentation of builtin functions calls was removed from GCC 5.0. To check the memory accessed by such functions, userspace asan always uses interceptors for them. So now we should do this as well. This patch declares memset/memmove/memcpy as weak symbols. In mm/kasan/kasan.c we have our own implementation of those functions which checks memory before accessing it. Default memset/memmove/memcpy now now always have aliases with '__' prefix. For files that built without kasan instrumentation (e.g. mm/slub.c) original mem* replaced (via #define) with prefixed variants, cause we don't want to check memory accesses there. Signed-off-by:
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Andrey Ryabinin authored
This is a test module doing various nasty things like out of bounds accesses, use after free. It is useful for testing kernel debugging features like kernel address sanitizer. It mostly concentrates on testing of slab allocator, but we might want to add more different stuff here in future (like stack/global variables out of bounds accesses and so on). Signed-off-by:
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Andrey Ryabinin authored
kmalloc internally round up allocation size, and kmemleak uses rounded up size as object's size. This makes kasan to complain while kmemleak scans memory or calculates of object's checksum. The simplest solution here is to disable kasan. Signed-off-by:
Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by:
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Andrey Ryabinin authored
We need to manually unpoison rounded up allocation size for dname to avoid kasan's reports in dentry_string_cmp(). When CONFIG_DCACHE_WORD_ACCESS=y dentry_string_cmp may access few bytes beyound requested in kmalloc() size. dentry_string_cmp() relates on that fact that dentry allocated using kmalloc and kmalloc internally round up allocation size. So this is not a bug, but this makes kasan to complain about such accesses. To avoid such reports we mark rounded up allocation size in shadow as accessible. Signed-off-by:
Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by:
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Andrey Ryabinin authored
With this patch kasan will be able to catch bugs in memory allocated by slub. Initially all objects in newly allocated slab page, marked as redzone. Later, when allocation of slub object happens, requested by caller number of bytes marked as accessible, and the rest of the object (including slub's metadata) marked as redzone (inaccessible). We also mark object as accessible if ksize was called for this object. There is some places in kernel where ksize function is called to inquire size of really allocated area. Such callers could validly access whole allocated memory, so it should be marked as accessible. Code in slub.c and slab_common.c files could validly access to object's metadata, so instrumentation for this files are disabled. Signed-off-by:
Dmitry Chernenkov <dmitryc@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Signed-off-by:
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Andrey Ryabinin authored
It's ok for slub to access memory that marked by kasan as inaccessible (object's metadata). Kasan shouldn't print report in that case because these accesses are valid. Disabling instrumentation of slub.c code is not enough to achieve this because slub passes pointer to object's metadata into external functions like memchr_inv(). We don't want to disable instrumentation for memchr_inv() because this is quite generic function, and we don't want to miss bugs. metadata_access_enable/metadata_access_disable used to tell KASan where accesses to metadata starts/end, so we could temporarily disable KASan reports. Signed-off-by:
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Andrey Ryabinin authored
Remove static and add function declarations to linux/slub_def.h so it could be used by kernel address sanitizer. Signed-off-by:
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Andrey Ryabinin authored
virt_to_obj takes kmem_cache address, address of slab page, address x pointing somewhere inside slab object, and returns address of the beginning of object. Signed-off-by:
Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by:
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Andrey Ryabinin authored
Add kernel address sanitizer hooks to mark allocated page's addresses as accessible in corresponding shadow region. Mark freed pages as inaccessible. Signed-off-by:
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Andrey Ryabinin authored
This patch adds arch specific code for kernel address sanitizer. 16TB of virtual addressed used for shadow memory. It's located in range [ffffec0000000000 - fffffc0000000000] between vmemmap and %esp fixup stacks. At early stage we map whole shadow region with zero page. Latter, after pages mapped to direct mapping address range we unmap zero pages from corresponding shadow (see kasan_map_shadow()) and allocate and map a real shadow memory reusing vmemmap_populate() function. Also replace __pa with __pa_nodebug before shadow initialized. __pa with CONFIG_DEBUG_VIRTUAL=y make external function call (__phys_addr) __phys_addr is instrumented, so __asan_load could be called before shadow area initialized. Signed-off-by:
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Andrey Ryabinin authored
Currently memory hotplug won't work with KASan. As we don't have shadow for hotplugged memory, kernel will crash on the first access to it. To make this work we will need to allocate shadow for new memory. At some future point proper memory hotplug support will be implemented. Until then, print a warning at startup and disable memory hot-add. Signed-off-by:
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Andrey Ryabinin authored
Kernel Address sanitizer (KASan) is a dynamic memory error detector. It provides fast and comprehensive solution for finding use-after-free and out-of-bounds bugs. KASAN uses compile-time instrumentation for checking every memory access, therefore GCC > v4.9.2 required. v4.9.2 almost works, but has issues with putting symbol aliases into the wrong section, which breaks kasan instrumentation of globals. This patch only adds infrastructure for kernel address sanitizer. It's not available for use yet. The idea and some code was borrowed from [1]. Basic idea: The main idea of KASAN is to use shadow memory to record whether each byte of memory is safe to access or not, and use compiler's instrumentation to check the shadow memory on each memory access. Address sanitizer uses 1/8 of the memory addressable in kernel for shadow memory and uses direct mapping with a scale and offset to translate a memory address to its corresponding shadow address. Here is function to translate address to corresponding shadow address: unsigned long kasan_mem_to_shadow(unsigned long addr) { return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET; } where KASAN_SHADOW_SCALE_SHIFT = 3. So for every 8 bytes there is one corresponding byte of shadow memory. The following encoding used for each shadow byte: 0 means that all 8 bytes of the corresponding memory region are valid for access; k (1 <= k <= 7) means that the first k bytes are valid for access, and other (8 - k) bytes are not; Any negative value indicates that the entire 8-bytes are inaccessible. Different negative values used to distinguish between different kinds of inaccessible memory (redzones, freed memory) (see mm/kasan/kasan.h). To be able to detect accesses to bad memory we need a special compiler. Such compiler inserts a specific function calls (__asan_load*(addr), __asan_store*(addr)) before each memory access of size 1, 2, 4, 8 or 16. These functions check whether memory region is valid to access or not by checking corresponding shadow memory. If access is not valid an error printed. Historical background of the address sanitizer from Dmitry Vyukov: "We've developed the set of tools, AddressSanitizer (Asan), ThreadSanitizer and MemorySanitizer, for user space. We actively use them for testing inside of Google (continuous testing, fuzzing, running prod services). To date the tools have found more than 10'000 scary bugs in Chromium, Google internal codebase and various open-source projects (Firefox, OpenSSL, gcc, clang, ffmpeg, MySQL and lots of others): [2] [3] [4]. The tools are part of both gcc and clang compilers. We have not yet done massive testing under the Kernel AddressSanitizer (it's kind of chicken and egg problem, you need it to be upstream to start applying it extensively). To date it has found about 50 bugs. Bugs that we've found in upstream kernel are listed in [5]. We've also found ~20 bugs in out internal version of the kernel. Also people from Samsung and Oracle have found some. [...] As others noted, the main feature of AddressSanitizer is its performance due to inline compiler instrumentation and simple linear shadow memory. User-space Asan has ~2x slowdown on computational programs and ~2x memory consumption increase. Taking into account that kernel usually consumes only small fraction of CPU and memory when running real user-space programs, I would expect that kernel Asan will have ~10-30% slowdown and similar memory consumption increase (when we finish all tuning). I agree that Asan can well replace kmemcheck. We have plans to start working on Kernel MemorySanitizer that finds uses of unitialized memory. Asan+Msan will provide feature-parity with kmemcheck. As others noted, Asan will unlikely replace debug slab and pagealloc that can be enabled at runtime. Asan uses compiler instrumentation, so even if it is disabled, it still incurs visible overheads. Asan technology is easily portable to other architectures. Compiler instrumentation is fully portable. Runtime has some arch-dependent parts like shadow mapping and atomic operation interception. They are relatively easy to port." Comparison with other debugging features: ======================================== KMEMCHECK: - KASan can do almost everything that kmemcheck can. KASan uses compile-time instrumentation, which makes it significantly faster than kmemcheck. The only advantage of kmemcheck over KASan is detection of uninitialized memory reads. Some brief performance testing showed that kasan could be x500-x600 times faster than kmemcheck: $ netperf -l 30 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec no debug: 87380 16384 16384 30.00 41624.72 kasan inline: 87380 16384 16384 30.00 12870.54 kasan outline: 87380 16384 16384 30.00 10586.39 kmemcheck: 87380 16384 16384 30.03 20.23 - Also kmemcheck couldn't work on several CPUs. It always sets number of CPUs to 1. KASan doesn't have such limitation. DEBUG_PAGEALLOC: - KASan is slower than DEBUG_PAGEALLOC, but KASan works on sub-page granularity level, so it able to find more bugs. SLUB_DEBUG (poisoning, redzones): - SLUB_DEBUG has lower overhead than KASan. - SLUB_DEBUG in most cases are not able to detect bad reads, KASan able to detect both reads and writes. - In some cases (e.g. redzone overwritten) SLUB_DEBUG detect bugs only on allocation/freeing of object. KASan catch bugs right before it will happen, so we always know exact place of first bad read/write. [1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel [2] https://code.google.com/p/address-sanitizer/wiki/FoundBugs [3] https://code.google.com/p/thread-sanitizer/wiki/FoundBugs [4] https://code.google.com/p/memory-sanitizer/wiki/FoundBugs [5] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel#Trophies Based on work by Andrey Konovalov. Signed-off-by:Michal Marek <mmarek@suse.cz> Signed-off-by:
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Andrey Ryabinin authored
To be consistent with other compiler attributes introduce __alias(symbol) macro expanding into __attribute__((alias(#symbol))) Signed-off-by:
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Andrew Morton authored
The patch "module: fix types of device tables aliases" newly requires that invocations of MODULE_DEVICE_TABLE(type, name); come *after* the definition of `name'. That is reasonable, but some drivers weren't doing this. Fix them. Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: David Miller <davem@davemloft.net> Cc: Hans Verkuil <hverkuil@xs4all.nl> Acked-by:
Mauro Carvalho Chehab <mchehab@osg.samsung.com> Signed-off-by:
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Davidlohr Bueso authored
After waking up a task waiting for an event, we explicitly mark it as TASK_RUNNING (which is necessary as we do the checks for wakeups as TASK_INTERRUPTIBLE). Once running and dealing with actually delivering the events, we're obviously not planning on calling schedule, thus we can relax the implied barrier and simply update the state with __set_current_state(). Signed-off-by:
Davidlohr Bueso <dbueso@suse.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by:
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Joe Perches authored
Uses of struct of_device_id are most commonly const. Suggest using it as such. Signed-off-by:
Joe Perches <joe@perches.com> Acked-by:
Rob Herring <robh@kernel.org> Signed-off-by:
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Joe Perches authored
Naming the tool that found an issue in the subject line isn't very useful. Emit a warning when a common tool (currently checkpatch, sparse or smatch) is in the subject line. Signed-off-by:
Al Viro <viro@ZenIV.linux.org.uk> Acked-by:
Dan Carpenter <dan.carpenter@oracle.com> Acked-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by:
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Joe Perches authored
The preferred style for a commit reference in a commit log is: commit <foo> ("<title line>") A recent commit removed this check for parentheses. Add it back. Signed-off-by: -
Joe Perches authored
Some prefer code to have spaces around arithmetic so instead of: a = b*c+d; suggest a = b * c + d; Signed-off-by: -
Joe Perches authored
Just neatening... Signed-off-by:
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Joe Perches authored
Code like: if (a < sizeof(<type>) && and { .len = sizeof(<type>) }, incorrectly emits that warning, so add more exceptions to avoid the warning. Signed-off-by: -
Heba Aamer authored
Improve the format specifier test by removing any %% before looking for any remaining % format specifier. Signed-off-by:
Heba Aamer <heba93aamer@gmail.com> Signed-off-by:
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Joe Perches authored
There's a --strict test for these blank lines. Add the ability to automatically remove them with --fix. Signed-off-by:
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Joe Perches authored
bsd and sysv use different typedefs for unsigned types. These are in types.h but not in checkpatch, so add them to checkpatch's ability to know types. This can avoid false positives for code like: void foo(void) { int x; uint y; [...]; } where checkpatch incorrectly emits a warning for "missing a blank line after declarations". Signed-off-by: -
Joe Perches authored
If a git commit description is split on consecutive lines, coalesce it before testing. This allows: commit <foo> ("some long description") Signed-off-by:Paul Bolle <pebolle@tiscali.nl> Tested-by:
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Joe Perches authored
Add a test for probably likely/unlikely misuses where the comparison is likely misplaced if (likely(foo) > 0) vs if (likely(foo > 0)) Signed-off-by:
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Joe Perches authored
The git commit message can be confusing, Try to clarify the message a bit to reduce the confusion when emitted. Show the correct form using Please use git commit description style 'commit <12+ chars of sha1> ("<title line>")' and if the git commit sha1 is unique, show the right sha1 to use with the actual title Signed-off-by:Prarit Bhargava <prarit@redhat.com> Tested-by:
Chris Rorvick <chris@rorvick.com> Acked-by:
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Joe Perches authored
Convert all the comments to spaces before testing for single statement macros. Reported-by:
Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Signed-off-by:
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Christoph Jaeger authored
Discourage the use of keyword 'boolean' for type definition attributes of config options as support for it will be dropped later on. See http://lkml.kernel.org/r/cover.1418003065.git.cj@linux.comSigned-off-by:
Christoph Jaeger <cj@linux.com> Suggested-by:
Daniel Borkmann <dborkman@redhat.com> Cc: Joe Perches <joe@perches.com> Acked-by:
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Paolo Bonzini authored
KERN_<LEVEL> is never redundant with printk_ratelimited or printk_once. (Except perhaps in the sense that you could use e.g. pr_err_ratelimited or pr_err_once, but that would apply to printk as well). Signed-off-by:
Paolo Bonzini <pbonzini@redhat.com> Cc: Andy Whitcroft <apw@canonical.com> Acked-by:
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Joe Perches authored
Just like "__cold", ignore the __pure gcc attribute macro so pointer warnings aren't generated for uses like "int * __pure fn(...)" Signed-off-by:
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Joe Perches authored
Add world writable permissions tests for the various functions like debugfs etc... Add $String type for $FuncArg so that string constants are matched. Signed-off-by:
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Joe Perches authored
Since commit fe7c36c7 ("Makefile: Build with -Werror=date-time if the compiler supports it"), use of __DATE__, __TIME__, and __TIMESTAMP__ has not been allowed. As this test is gcc version specific (> 4.9), it hasn't prevented a few new uses from creeping into the kernel sources. Make checkpatch complain about them. Signed-off-by:
Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by:
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Tejun Heo authored
Now that all bitmap formatting usages have been converted to '%*pb[l]', the separate formatting functions are unnecessary. The following functions are removed. * bitmap_scn[list]printf() * cpumask_scnprintf(), cpulist_scnprintf() * [__]nodemask_scnprintf(), [__]nodelist_scnprintf() * seq_bitmap[_list](), seq_cpumask[_list](), seq_nodemask[_list]() * seq_buf_bitmask() Signed-off-by:
Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:
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