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    Subject[PATCH 5.15 516/667] f2fs: fix to avoid f2fs_bug_on() in dec_valid_node_count()
    Date
    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
    @@ -2487,11 +2487,17 @@ 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++;

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