From 72e544b1b28325fe78a4687b980871a7e4101f76 Mon Sep 17 00:00:00 2001
From: Fedor Pchelkin <pchelkin@ispras.ru>
Date: Tue, 17 Jan 2023 13:52:26 +0300
Subject: [PATCH] squashfs: harden sanity check in squashfs_read_xattr_id_table
Git-commit: 72e544b1b28325fe78a4687b980871a7e4101f76
Patch-mainline: v6.2-rc7
References: git-fixes
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@ispras.ru
Fixes: 506220d2ba21 ("squashfs: add more sanity checks in xattr id lookup")
Reported-by: <syzbot+082fa4af80a5bb1a9843@syzkaller.appspotmail.com>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/squashfs/xattr_id.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/squashfs/xattr_id.c b/fs/squashfs/xattr_id.c
index 087cab8c78f4..f6d78cbc3e74 100644
--- a/fs/squashfs/xattr_id.c
+++ b/fs/squashfs/xattr_id.c
@@ -76,7 +76,7 @@ __le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
/* 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);
--
2.35.3