[PATCH 5.18 708/879] f2fs: fix to avoid f2fs_bug_on() in dec_valid_node_count()

Greg Kroah-Hartman
2022-06-08T02:03:27Z

From: Chao Yu <chao@kernel.org>

commit 4d17e6fe9293d57081ffdc11e1cf313e25e8fd9e upstream.

As Yanming reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=215897

I have encountered a bug in F2FS file system in kernel v5.17.

The kernel should enable CONFIG_KASAN=y and CONFIG_KASAN_INLINE=y. You can
reproduce the bug by running the following commands:

The kernel message is shown below:

kernel BUG at fs/f2fs/f2fs.h:2511!
Call Trace:
f2fs_remove_inode_page+0x2a2/0x830
f2fs_evict_inode+0x9b7/0x1510
evict+0x282/0x4e0
do_unlinkat+0x33a/0x540
__x64_sys_unlinkat+0x8e/0xd0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae

The root cause is: .total_valid_block_count or .total_valid_node_count
could fuzzed to zero, then once dec_valid_node_count() was called, it
will cause BUG_ON(), this patch fixes to print warning info and set
SBI_NEED_FSCK into CP instead of panic.

Cc: stable@vger.kernel.org
Reported-by: Ming Yan <yanming@tju.edu.cn>
Signed-off-by: Chao Yu <chao.yu@oppo.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/f2fs/f2fs.h | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2605,11 +2605,17 @@ static inline void dec_valid_node_count(
{
spin_lock(&sbi->stat_lock);

- f2fs_bug_on(sbi, !sbi->total_valid_block_count);
- f2fs_bug_on(sbi, !sbi->total_valid_node_count);
+ if (unlikely(!sbi->total_valid_block_count ||
+ !sbi->total_valid_node_count)) {
+ f2fs_warn(sbi, "dec_valid_node_count: inconsistent block counts, total_valid_block:%u, total_valid_node:%u",
+ sbi->total_valid_block_count,
+ sbi->total_valid_node_count);
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ } else {
+ sbi->total_valid_block_count--;
+ sbi->total_valid_node_count--;
+ }

- sbi->total_valid_node_count--;
- sbi->total_valid_block_count--;
if (sbi->reserved_blocks &&
sbi->current_reserved_blocks < sbi->reserved_blocks)
sbi->current_reserved_blocks++;