• Michael Ellerman's avatar
    powerpc/crypto/crc32c-vpmsum: Fix missing preempt_disable() · 5c67d541
    Michael Ellerman authored
    commit 4749228f upstream.
    
    In crc32c_vpmsum() we call enable_kernel_altivec() without first
    disabling preemption, which is not allowed:
    
      WARNING: CPU: 9 PID: 2949 at ../arch/powerpc/kernel/process.c:277 enable_kernel_altivec+0x100/0x120
      Modules linked in: dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c vmx_crypto ...
      CPU: 9 PID: 2949 Comm: docker Not tainted 4.11.0-rc5-compiler_gcc-6.3.1-00033-g308ac756 #381
      ...
      NIP [c00000000001e320] enable_kernel_altivec+0x100/0x120
      LR [d000000003df0910] crc32c_vpmsum+0x108/0x150 [crc32c_vpmsum]
      Call Trace:
        0xc138fd09 (unreliable)
        crc32c_vpmsum+0x108/0x150 [crc32c_vpmsum]
        crc32c_vpmsum_update+0x3c/0x60 [crc32c_vpmsum]
        crypto_shash_update+0x88/0x1c0
        crc32c+0x64/0x90 [libcrc32c]
        dm_bm_checksum+0x48/0x80 [dm_persistent_data]
        sb_check+0x84/0x120 [dm_thin_pool]
        dm_bm_validate_buffer.isra.0+0xc0/0x1b0 [dm_persistent_data]
        dm_bm_read_lock+0x80/0xf0 [dm_persistent_data]
        __create_persistent_data_objects+0x16c/0x810 [dm_thin_pool]
        dm_pool_metadata_open+0xb0/0x1a0 [dm_thin_pool]
        pool_ctr+0x4cc/0xb60 [dm_thin_pool]
        dm_table_add_target+0x16c/0x3c0
        table_load+0x184/0x400
        ctl_ioctl+0x2f0/0x560
        dm_ctl_ioctl+0x38/0x50
        do_vfs_ioctl+0xd8/0x920
        SyS_ioctl+0x68/0xc0
        system_call+0x38/0xfc
    
    It used to be sufficient just to call pagefault_disable(), because that
    also disabled preemption. But the two were decoupled in commit 8222dbe2
    ("sched/preempt, mm/fault: Decouple preemption from the page fault
    logic") in mid 2015.
    
    So add the missing preempt_disable/enable(). We should also call
    disable_kernel_fp(), although it does nothing by default, there is a
    debug switch to make it active and all enables should be paired with
    disables.
    
    Fixes: 6dd7a82c ("crypto: powerpc - Add POWER8 optimised crc32c")
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    5c67d541
crc32c-vpmsum_glue.c 3.88 KB