commit 901ce9705f upstream.
syzbot reported a WARNING in nilfs_rmdir. [1]
Because the inode bitmap is corrupted, an inode with an inode number that
should exist as a ".nilfs" file was reassigned by nilfs_mkdir for "file0",
causing an inode duplication during execution. And this causes an
underflow of i_nlink in rmdir operations.
The inode is used twice by the same task to unmount and remove directories
".nilfs" and "file0", it trigger warning in nilfs_rmdir.
Avoid to this issue, check i_nlink in nilfs_iget(), if it is 0, it means
that this inode has been deleted, and iput is executed to reclaim it.
[1]
WARNING: CPU: 1 PID: 5824 at fs/inode.c:407 drop_nlink+0xc4/0x110 fs/inode.c:407
...
Call Trace:
<TASK>
nilfs_rmdir+0x1b0/0x250 fs/nilfs2/namei.c:342
vfs_rmdir+0x3a3/0x510 fs/namei.c:4394
do_rmdir+0x3b5/0x580 fs/namei.c:4453
__do_sys_rmdir fs/namei.c:4472 [inline]
__se_sys_rmdir fs/namei.c:4470 [inline]
__x64_sys_rmdir+0x47/0x50 fs/namei.c:4470
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Link: https://lkml.kernel.org/r/20241209065759.6781-1-konishi.ryusuke@gmail.com
Fixes: d25006523d ("nilfs2: pathname operations")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+9260555647a5132edd48@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9260555647a5132edd48
Tested-by: syzbot+9260555647a5132edd48@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
284760b320