The patch titled
Subject: squashfs: harden sanity check in squashfs_read_xattr_id_table
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
squashfs-harden-sanity-check-in-squashfs_read_xattr_id_table.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/squashfs-harden-sanity-check-in-squashfs_read_xattr_id_table.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Subject: squashfs: harden sanity check in squashfs_read_xattr_id_table
Date: Tue, 17 Jan 2023 13:52:26 +0300
While mounting a corrupted filesystem, a signed integer '*xattr_ids' can
become less than zero. This leads to the incorrect computation of 'len'
and 'indexes' values which can cause null-ptr-deref in copy_bio_to_actor()
or out-of-bounds accesses in the next sanity checks inside
squashfs_read_xattr_id_table().
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Link: https://lkml.kernel.org/r/20230117105226.329303-2-pchelkin@xxxxxxxxx
Fixes: 506220d2ba21 ("squashfs: add more sanity checks in xattr id lookup")
Reported-by: <syzbot+082fa4af80a5bb1a9843@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
Cc: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/fs/squashfs/xattr_id.c~squashfs-harden-sanity-check-in-squashfs_read_xattr_id_table
+++ a/fs/squashfs/xattr_id.c
@@ -76,7 +76,7 @@ __le64 *squashfs_read_xattr_id_table(str
/* Sanity check values */
/* there is always at least one xattr id */
- if (*xattr_ids == 0)
+ if (*xattr_ids <= 0)
return ERR_PTR(-EINVAL);
len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
_
Patches currently in -mm which might be from pchelkin@xxxxxxxxx are
squashfs-harden-sanity-check-in-squashfs_read_xattr_id_table.patch
