4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxx> Acked-by: Phillip Lougher <phillip.lougher@xxxxxxxxx> Cc: stable@xxxxxxxxxx Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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)