crypto: scomp - fix req->dst buffer overflow

[ Upstream commit 744e188 ]

The req->dst buffer size should be checked before copying from the
scomp_scratch->dst to avoid req->dst buffer overflow problem.

Fixes: 1ab53a7 ("crypto: acomp - add driver-side scomp interface")
Reported-by: [email protected]
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Chengming Zhou <[email protected]>
Reviewed-by: Barry Song <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

crypto/scompress.c

@@ -124,6 +124,7 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 	struct crypto_scomp *scomp = *tfm_ctx;
 	void **ctx = acomp_request_ctx(req);
 	struct scomp_scratch *scratch;
+	unsigned int dlen;
 	int ret;
 
 	if (!req->src || !req->slen || req->slen > SCOMP_SCRATCH_SIZE)
@@ -135,6 +136,8 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 	if (!req->dlen || req->dlen > SCOMP_SCRATCH_SIZE)
 		req->dlen = SCOMP_SCRATCH_SIZE;
 
+	dlen = req->dlen;
+
 	scratch = raw_cpu_ptr(&scomp_scratch);
 	spin_lock(&scratch->lock);
 
@@ -152,6 +155,9 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 				ret = -ENOMEM;
 				goto out;
 			}
+		} else if (req->dlen > dlen) {
+			ret = -ENOSPC;
+			goto out;
 		}
 		scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
 					 1);