4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alexander Potapenko glider@google.com
commit 3876bbe27d04b848750d5310a37d6b76b593f648 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: Alexander Potapenko glider@google.com Signed-off-by: Eric Biggers ebiggers@google.com Cc: stable@vger.kernel.org # v4.6 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/mbcache.c | 1 + 1 file changed, 1 insertion(+)
--- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -93,6 +93,7 @@ int mb_cache_entry_create(struct mb_cach entry->e_key = key; entry->e_block = block; entry->e_reusable = reusable; + entry->e_referenced = 0; head = mb_cache_entry_head(cache, key); hlist_bl_lock(head); hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {