[PATCH] crypto: deflate - fix decompression window size

[Giovanni Cabiddu <giovanni.cabiddu@intel.com>]

deflate_decompress() initializes the inflate stream with windowBits set
to -DEFLATE_DEF_WINBITS (11 bits, 2KB window). Valid raw DEFLATE streams
allow window sizes up to MAX_WBITS (15 bits, 32KB).  Using a smaller
window than the one used during compression causes decompression to fail
for externally generated data. This might occur if data is compressed
with a compressor that is not deflate-generic (i.e. this
implementation).

Use -MAX_WBITS when calling zlib_inflateInit2() to accept all valid raw
DEFLATE streams. The inflate workspace allocated in deflate_alloc_stream()
is already sized using zlib_inflate_workspacesize(), which accounts for
the maximum window size, so no allocation change is needed.

Fixes: 08cabc7d3c86 ("crypto: deflate - Convert to acomp")
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Laurent M Coquerel <laurent.m.coquerel@intel.com>
---
 crypto/deflate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/deflate.c b/crypto/deflate.c
index 46fc7def8d4c..d347e506e6c3 100644
--- a/crypto/deflate.c
+++ b/crypto/deflate.c
@@ -203,7 +203,7 @@ static int deflate_decompress(struct acomp_req *req)
 	s = crypto_acomp_lock_stream_bh(&deflate_streams);
 	ds = s->ctx;
 
-	err = zlib_inflateInit2(&ds->stream, -DEFLATE_DEF_WINBITS);
+	err = zlib_inflateInit2(&ds->stream, -MAX_WBITS);
 	if (err != Z_OK) {
 		err = -EINVAL;
 		goto out;
-- 
2.53.0