crypto: scomp - fix req->dst buffer overflow

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

Fixes: 1ab53a77b772 ("crypto: acomp - add driver-side scomp interface")
Reported-by: syzbot+3eff5e51bf1db122a16e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/0000000000000b05cd060d6b5511@google.com/
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Barry Song <v-songbaohua@oppo.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/scompress.c b/crypto/scompress.c
index 442a82c9de7def1f876045d6204da9733c9a5994..b108a30a7600140e5ed616b84431d4031fc905e4 100644 (file)
--- a/crypto/scompress.c
+++ b/crypto/scompress.c
@@ -117,6 +117,7 @@ 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)
@@ -128,6 +129,8 @@ 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);
 
@@ -145,6 +148,9 @@ 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);