The patch titled Subject: nilfs2: prevent use of deleted inode has been added to the -mm mm-hotfixes-unstable branch. Its filename is nilfs2-prevent-use-of-deleted-inode.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days

------------------------------------------------------ From: Edward Adam Davis eadavis@qq.com Subject: nilfs2: prevent use of deleted inode Date: Mon, 9 Dec 2024 15:56:52 +0900

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: d25006523d0b ("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 ---

fs/nilfs2/inode.c | 8 +++++++- fs/nilfs2/namei.c | 5 +++++ 2 files changed, 12 insertions(+), 1 deletion(-)

--- a/fs/nilfs2/inode.c~nilfs2-prevent-use-of-deleted-inode +++ a/fs/nilfs2/inode.c @@ -544,8 +544,14 @@ struct inode *nilfs_iget(struct super_bl inode = nilfs_iget_locked(sb, root, ino); if (unlikely(!inode)) return ERR_PTR(-ENOMEM); - if (!(inode->i_state & I_NEW)) + + if (!(inode->i_state & I_NEW)) { + if (!inode->i_nlink) { + iput(inode); + return ERR_PTR(-ESTALE); + } return inode; + }

err = __nilfs_read_inode(sb, root, ino, inode); if (unlikely(err)) { --- a/fs/nilfs2/namei.c~nilfs2-prevent-use-of-deleted-inode +++ a/fs/nilfs2/namei.c @@ -67,6 +67,11 @@ nilfs_lookup(struct inode *dir, struct d inode = NULL; } else { inode = nilfs_iget(dir->i_sb, NILFS_I(dir)->i_root, ino); + if (inode == ERR_PTR(-ESTALE)) { + nilfs_error(dir->i_sb, + "deleted inode referenced: %lu", ino); + return ERR_PTR(-EIO); + } }

return d_splice_alias(inode, dentry); _

Patches currently in -mm which might be from eadavis@qq.com are

nilfs2-prevent-use-of-deleted-inode.patch