crypto: af_alg - fix NULL pointer dereference in

af_alg_free_areq_sgls() If allocating the ->tsgl member of 'struct af_alg_async_req' failed, during cleanup we dereferenced the NULL ->tsgl pointer in af_alg_free_areq_sgls(), because ->tsgl_entries was nonzero. Fix it by only freeing the ->tsgl list if it is non-NULL. This affected both algif_skcipher and algif_aead. Fixes: e870456 ("crypto: algif_skcipher - overhaul memory management") Fixes: d887c52 ("crypto: algif_aead - overhaul memory management") Reported-by: syzbot <[email protected]> Cc: <[email protected]> # v4.14+ Signed-off-by: Eric Biggers <[email protected]> Reviewed-by: Stephan Mueller <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
josf · Nov 29, 2017 · 887207e · 887207e
1 parent b32a7dc
commit 887207e
Showing 1 changed file with 7 additions and 6 deletions.
diff --git a/crypto/af_alg.c b/crypto/af_alg.c
@@ -672,14 +672,15 @@ void af_alg_free_areq_sgls(struct af_alg_async_req *areq)
 	}
 
 	tsgl = areq->tsgl;
-	for_each_sg(tsgl, sg, areq->tsgl_entries, i) {
-		if (!sg_page(sg))
-			continue;
-		put_page(sg_page(sg));
-	}
+	if (tsgl) {
+		for_each_sg(tsgl, sg, areq->tsgl_entries, i) {
+			if (!sg_page(sg))
+				continue;
+			put_page(sg_page(sg));
+		}
 
-	if (areq->tsgl && areq->tsgl_entries)
 		sock_kfree_s(sk, tsgl, areq->tsgl_entries * sizeof(*tsgl));
+	}
 }
 EXPORT_SYMBOL_GPL(af_alg_free_areq_sgls);