From 29e774dcb27116c06b9c57b1f1f14a1623738989 Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Tue, 17 Jan 2023 13:52:26 +0300 Subject: [PATCH] squashfs: harden sanity check in squashfs_read_xattr_id_table [ Upstream commit 72e544b1b28325fe78a4687b980871a7e4101f76 ] 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: Signed-off-by: Fedor Pchelkin Signed-off-by: Alexey Khoroshilov Cc: Phillip Lougher Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- 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 087cab8..f6d78cb 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); -- 2.7.4