linux-kernel - [PATCH 4.17 11/31] squashfs: more metadata hardening

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Date:   Sat,  4 Aug 2018 11:00:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Anatoly Trosinenko <anatoly.trosinenko@...il.com>,
        Phillip Lougher <phillip.lougher@...il.com>, stable@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.17 11/31] squashfs: more metadata hardening

4.17-stable review patch.  If anyone has any objections, please let me know.

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

From: Linus Torvalds <torvalds@...ux-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@...il.com>
Acked-by: Phillip Lougher <phillip.lougher@...il.com>
Cc: stable@...nel.org
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/squashfs/block.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -167,6 +167,8 @@ 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)