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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Anatoly Trosinenko" <anatoly.trosinenko@gmail.com>,
        "Phillip Lougher" <phillip.lougher@gmail.com>,
        "Linus Torvalds" <torvalds@linux-foundation.org>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.368843608@decadent.org.uk>
Subject: [PATCH 3.16 306/366] squashfs: more metadata hardening
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Torvalds <torvalds@linux-foundation.org>

commit d512584780d3e6a7cacb2f482834849453d444a1 upstream.

Anatoly reports another squashfs fuzzing issue, where the decompression
parameters themselves are in a compressed block.

This causes squashfs_read_data() to be called in order to read the
decompression options before the decompression stream having been set
up, making squashfs go sideways.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Acked-by: Phillip Lougher <phillip.lougher@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/squashfs/block.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -166,6 +166,8 @@ int squashfs_read_data(struct super_bloc
 	}
 
 	if (compressed) {
+		if (!msblk->stream)
+			goto read_failure;
 		length = squashfs_decompress(msblk, bh, b, offset, length,
 			output);
 		if (length < 0)