On Thu, Oct 09, 2025 at 10:54:40AM +0800, Chao Yu wrote: > On 10/3/2025 9:47 PM, Nikola Z. Ivanov wrote: > > Current i_nlink corruption check does not take into account > > directory inodes which have one additional i_nlink for their "." entry. > > > > Add additional check and a common corruption path. > > > > Reported-by: [email protected] > > Closes: https://syzkaller.appspot.com/bug?extid=c07d47c7bc68f47b9083 > > Fixes: 81edb983b3f5 ("f2fs: add check for deleted inode") > > Signed-off-by: Nikola Z. Ivanov <[email protected]> > > --- > > fs/f2fs/namei.c | 28 ++++++++++++++++++++-------- > > 1 file changed, 20 insertions(+), 8 deletions(-) > > > > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c > > index b882771e4699..68b33e8089b0 100644 > > --- a/fs/f2fs/namei.c > > +++ b/fs/f2fs/namei.c > > @@ -502,12 +502,14 @@ static struct dentry *f2fs_lookup(struct inode *dir, > > struct dentry *dentry, > > goto out; > > } > > - if (inode->i_nlink == 0) { > > + if (unlikely(inode->i_nlink == 0)) { > > f2fs_warn(F2FS_I_SB(inode), "%s: inode (ino=%lx) has zero > > i_nlink", > > __func__, inode->i_ino); > > - err = -EFSCORRUPTED; > > - set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); > > - goto out_iput; > > + goto corrupted; > > + } else if (unlikely(S_ISDIR(inode->i_mode) && inode->i_nlink == 1)) { > > + f2fs_warn(F2FS_I_SB(inode), "%s: directory inode (ino=%lx) has > > a single i_nlink", > > + __func__, inode->i_ino); > > + goto corrupted; > > Can we detect such corruption in sanity_check_inode() as well? So that if > f2fs internal flow calls f2fs_iget() on corrupted inode, we can set > SBI_NEED_FSCK > flag and then triggering fsck repairment later. > > Thanks, > > > } > > if (IS_ENCRYPTED(dir) && > > @@ -533,6 +535,9 @@ static struct dentry *f2fs_lookup(struct inode *dir, > > struct dentry *dentry, > > trace_f2fs_lookup_end(dir, !IS_ERR_OR_NULL(new) ? new : dentry, > > ino, IS_ERR(new) ? PTR_ERR(new) : err); > > return new; > > +corrupted: > > + err = -EFSCORRUPTED; > > + set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); > > out_iput: > > iput(inode); > > out: > > @@ -572,10 +577,11 @@ static int f2fs_unlink(struct inode *dir, struct > > dentry *dentry) > > if (unlikely(inode->i_nlink == 0)) { > > f2fs_warn(F2FS_I_SB(inode), "%s: inode (ino=%lx) has zero > > i_nlink", > > __func__, inode->i_ino); > > - err = -EFSCORRUPTED; > > - set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); > > - f2fs_folio_put(folio, false); > > - goto fail; > > + goto corrupted; > > + } else if (unlikely(S_ISDIR(inode->i_mode) && inode->i_nlink == 1)) { > > + f2fs_warn(F2FS_I_SB(inode), "%s: directory inode (ino=%lx) has > > a single i_nlink", > > + __func__, inode->i_ino); > > + goto corrupted; > > } > > f2fs_balance_fs(sbi, true); > > @@ -601,6 +607,12 @@ static int f2fs_unlink(struct inode *dir, struct > > dentry *dentry) > > if (IS_DIRSYNC(dir)) > > f2fs_sync_fs(sbi->sb, 1); > > + > > + goto fail; > > +corrupted: > > + err = -EFSCORRUPTED; > > + set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK); > > + f2fs_folio_put(folio, false); > > fail: > > trace_f2fs_unlink_exit(inode, err); > > return err; >
Hi Chao, Thank you for the suggestion. I will add this to sanity_check_inode and remove it from f2fs_lookup as it becomes redundant since f2fs_lookup obtains the inode through f2fs_iget. For f2fs_unlink I will move the i_nlink == 1 check to f2fs_rmdir. I will send v2 as soon as I do some more testing. _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
