[PATCH 4.19 151/168] fs/minix: dont allow getting deleted inodes

Greg Kroah-Hartman
2020-08-17T17:38:27Z

From: Eric Biggers <ebiggers@google.com>

commit facb03dddec04e4aac1bb2139accdceb04deb1f3 upstream.

If an inode has no links, we need to mark it bad rather than allowing it
to be accessed. This avoids WARNINGs in inc_nlink() and drop_nlink() when
doing directory operations on a fuzzed filesystem.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+a9ac3de1b5de5fb10efc@syzkaller.appspotmail.com
Reported-by: syzbot+df958cf5688a96ad3287@syzkaller.appspotmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Qiujun Huang <anenbupt@gmail.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200628060846.682158-3-ebiggers@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/minix/inode.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

--- a/fs/minix/inode.c
+++ b/fs/minix/inode.c
@@ -471,6 +471,13 @@ static struct inode *V1_minix_iget(struc
iget_failed(inode);
return ERR_PTR(-EIO);
}
+ if (raw_inode->i_nlinks == 0) {
+ printk("MINIX-fs: deleted inode referenced: %lu\n",
+ inode->i_ino);
+ brelse(bh);
+ iget_failed(inode);
+ return ERR_PTR(-ESTALE);
+ }
inode->i_mode = raw_inode->i_mode;
i_uid_write(inode, raw_inode->i_uid);
i_gid_write(inode, raw_inode->i_gid);
@@ -504,6 +511,13 @@ static struct inode *V2_minix_iget(struc
iget_failed(inode);
return ERR_PTR(-EIO);
}
+ if (raw_inode->i_nlinks == 0) {
+ printk("MINIX-fs: deleted inode referenced: %lu\n",
+ inode->i_ino);
+ brelse(bh);
+ iget_failed(inode);
+ return ERR_PTR(-ESTALE);
+ }
inode->i_mode = raw_inode->i_mode;
i_uid_write(inode, raw_inode->i_uid);
i_gid_write(inode, raw_inode->i_gid);