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    Subject[PATCH 4.19 038/118] f2fs: fix to avoid panic in dec_valid_block_count()
    Date
    [ Upstream commit 5e159cd349bf3a31fb7e35c23a93308eb30f4f71 ]

    As Jungyeon reported in bugzilla:

    https://bugzilla.kernel.org/show_bug.cgi?id=203209

    - Overview
    When mounting the attached crafted image and running program, I got this error.
    Additionally, it hangs on sync after the this script.

    The image is intentionally fuzzed from a normal f2fs image for testing and I enabled option CONFIG_F2FS_CHECK_FS on.

    - Reproduces
    cc poc_01.c
    ./run.sh f2fs
    sync

    kernel BUG at fs/f2fs/f2fs.h:1788!
    RIP: 0010:f2fs_truncate_data_blocks_range+0x342/0x350
    Call Trace:
    f2fs_truncate_blocks+0x36d/0x3c0
    f2fs_truncate+0x88/0x110
    f2fs_setattr+0x3e1/0x460
    notify_change+0x2da/0x400
    do_truncate+0x6d/0xb0
    do_sys_ftruncate+0xf1/0x160
    do_syscall_64+0x43/0xf0
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

    The reason is dec_valid_block_count() will trigger kernel panic due to
    inconsistent count in between inode.i_blocks and actual block.

    To avoid panic, let's just print debug message and set SBI_NEED_FSCK to
    give a hint to fsck for latter repairing.

    Signed-off-by: Chao Yu <yuchao0@huawei.com>
    [Jaegeuk Kim: fix build warning and add unlikely]
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/f2fs/f2fs.h | 12 ++++++++++--
    1 file changed, 10 insertions(+), 2 deletions(-)

    diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
    index a4b6eacf22ea..64f970cca1b4 100644
    --- a/fs/f2fs/f2fs.h
    +++ b/fs/f2fs/f2fs.h
    @@ -1744,6 +1744,7 @@ enospc:
    return -ENOSPC;
    }

    +void f2fs_msg(struct super_block *sb, const char *level, const char *fmt, ...);
    static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,
    struct inode *inode,
    block_t count)
    @@ -1752,13 +1753,21 @@ static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,

    spin_lock(&sbi->stat_lock);
    f2fs_bug_on(sbi, sbi->total_valid_block_count < (block_t) count);
    - f2fs_bug_on(sbi, inode->i_blocks < sectors);
    sbi->total_valid_block_count -= (block_t)count;
    if (sbi->reserved_blocks &&
    sbi->current_reserved_blocks < sbi->reserved_blocks)
    sbi->current_reserved_blocks = min(sbi->reserved_blocks,
    sbi->current_reserved_blocks + count);
    spin_unlock(&sbi->stat_lock);
    + if (unlikely(inode->i_blocks < sectors)) {
    + f2fs_msg(sbi->sb, KERN_WARNING,
    + "Inconsistent i_blocks, ino:%lu, iblocks:%llu, sectors:%llu",
    + inode->i_ino,
    + (unsigned long long)inode->i_blocks,
    + (unsigned long long)sectors);
    + set_sbi_flag(sbi, SBI_NEED_FSCK);
    + return;
    + }
    f2fs_i_blocks_write(inode, count, false, true);
    }

    @@ -2727,7 +2736,6 @@ static inline void f2fs_update_iostat(struct f2fs_sb_info *sbi,

    bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
    block_t blkaddr, int type);
    -void f2fs_msg(struct super_block *sb, const char *level, const char *fmt, ...);
    static inline void verify_blkaddr(struct f2fs_sb_info *sbi,
    block_t blkaddr, int type)
    {
    --
    2.20.1


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