• Alexander Potapenko's avatar
    mbcache: initialize entry->e_referenced in mb_cache_entry_create() · e96a2198
    Alexander Potapenko authored
    commit 3876bbe2 upstream.
    
    KMSAN reported use of uninitialized |entry->e_referenced| in a condition
    in mb_cache_shrink():
    
    ==================================================================
    BUG: KMSAN: use of uninitialized memory in mb_cache_shrink+0x3b4/0xc50 fs/mbcache.c:287
    CPU: 2 PID: 816 Comm: kswapd1 Not tainted 4.11.0-rc5+ #2877
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
    01/01/2011
    Call Trace:
     __dump_stack lib/dump_stack.c:16 [inline]
     dump_stack+0x172/0x1c0 lib/dump_stack.c:52
     kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:927
     __msan_warning_32+0x61/0xb0 mm/kmsan/kmsan_instr.c:469
     mb_cache_shrink+0x3b4/0xc50 fs/mbcache.c:287
     mb_cache_scan+0x67/0x80 fs/mbcache.c:321
     do_shrink_slab mm/vmscan.c:397 [inline]
     shrink_slab+0xc3d/0x12d0 mm/vmscan.c:500
     shrink_node+0x208f/0x2fd0 mm/vmscan.c:2603
     kswapd_shrink_node mm/vmscan.c:3172 [inline]
     balance_pgdat mm/vmscan.c:3289 [inline]
     kswapd+0x160f/0x2850 mm/vmscan.c:3478
     kthread+0x46c/0x5f0 kernel/kthread.c:230
     ret_from_fork+0x29/0x40 arch/x86/entry/entry_64.S:430
    chained origin:
     save_stack_trace+0x37/0x40 arch/x86/kernel/stacktrace.c:59
     kmsan_save_stack_with_flags mm/kmsan/kmsan.c:302 [inline]
     kmsan_save_stack mm/kmsan/kmsan.c:317 [inline]
     kmsan_internal_chain_origin+0x12a/0x1f0 mm/kmsan/kmsan.c:547
     __msan_store_shadow_origin_1+0xac/0x110 mm/kmsan/kmsan_instr.c:257
     mb_cache_entry_create+0x3b3/0xc60 fs/mbcache.c:95
     ext4_xattr_cache_insert fs/ext4/xattr.c:1647 [inline]
     ext4_xattr_block_set+0x4c82/0x5530 fs/ext4/xattr.c:1022
     ext4_xattr_set_handle+0x1332/0x20a0 fs/ext4/xattr.c:1252
     ext4_xattr_set+0x4d2/0x680 fs/ext4/xattr.c:1306
     ext4_xattr_trusted_set+0x8d/0xa0 fs/ext4/xattr_trusted.c:36
     __vfs_setxattr+0x703/0x790 fs/xattr.c:149
     __vfs_setxattr_noperm+0x27a/0x6f0 fs/xattr.c:180
     vfs_setxattr fs/xattr.c:223 [inline]
     setxattr+0x6ae/0x790 fs/xattr.c:449
     path_setxattr+0x1eb/0x380 fs/xattr.c:468
     SYSC_lsetxattr+0x8d/0xb0 fs/xattr.c:490
     SyS_lsetxattr+0x77/0xa0 fs/xattr.c:486
     entry_SYSCALL_64_fastpath+0x13/0x94
    origin:
     save_stack_trace+0x37/0x40 arch/x86/kernel/stacktrace.c:59
     kmsan_save_stack_with_flags mm/kmsan/kmsan.c:302 [inline]
     kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:198
     kmsan_kmalloc+0x7f/0xe0 mm/kmsan/kmsan.c:337
     kmem_cache_alloc+0x1c2/0x1e0 mm/slub.c:2766
     mb_cache_entry_create+0x283/0xc60 fs/mbcache.c:86
     ext4_xattr_cache_insert fs/ext4/xattr.c:1647 [inline]
     ext4_xattr_block_set+0x4c82/0x5530 fs/ext4/xattr.c:1022
     ext4_xattr_set_handle+0x1332/0x20a0 fs/ext4/xattr.c:1252
     ext4_xattr_set+0x4d2/0x680 fs/ext4/xattr.c:1306
     ext4_xattr_trusted_set+0x8d/0xa0 fs/ext4/xattr_trusted.c:36
     __vfs_setxattr+0x703/0x790 fs/xattr.c:149
     __vfs_setxattr_noperm+0x27a/0x6f0 fs/xattr.c:180
     vfs_setxattr fs/xattr.c:223 [inline]
     setxattr+0x6ae/0x790 fs/xattr.c:449
     path_setxattr+0x1eb/0x380 fs/xattr.c:468
     SYSC_lsetxattr+0x8d/0xb0 fs/xattr.c:490
     SyS_lsetxattr+0x77/0xa0 fs/xattr.c:486
     entry_SYSCALL_64_fastpath+0x13/0x94
    ==================================================================
    Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
    Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
    Cc: stable@vger.kernel.org # v4.6
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    e96a2198