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 --- fs/f2fs/f2fs.h | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index f3eda4f13646..56adc3b68e14 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -2605,11 +2605,17 @@ static inline void dec_valid_node_count(struct f2fs_sb_info *sbi, { 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++;