On Mon, 7 Apr 2025 at 05:57, syzbot
<syzbot+4036165fc595a74b09b2@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 16cd1c265776 Merge tag 'timers-cleanups-2025-04-06' of git..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12e7923f980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c79406130aa88d22
> dashboard link: https://syzkaller.appspot.com/bug?extid=4036165fc595a74b09b2
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14f9bd98580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1571c7e4580000
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
v6.15-rc1
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 969b458100fe..548f0e6aed54 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -273,6 +273,12 @@ static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
ovl_inode_lock(inode);
realfile->f_pos = file->f_pos;
+ /* Prevent WARNING in file_seek_cur_needs_f_lock() */
+ if (whence == SEEK_CUR && offset) {
+ offset += file->f_pos;
+ whence = SEEK_SET;
+ }
+
old_cred = ovl_override_creds(inode->i_sb);
ret = vfs_llseek(realfile, offset, whence);
ovl_revert_creds(old_cred);
