diff options
authorStephan Mueller <>2017-09-21 10:16:53 +0200
committerGreg Kroah-Hartman <>2017-09-24 22:29:15 +0200
commit753c7d770beff9d4c5133f3f63b6a2df85cec0bf (patch)
parente422681d2a4677f6521da485a5e574b9e78094c8 (diff)
crypto: AF_ALG - remove SGL terminator indicator when chaining
Fixed differently upstream as commit 2d97591ef43d ("crypto: af_alg - consolidation of duplicate code") The SGL is MAX_SGL_ENTS + 1 in size. The last SG entry is used for the chaining and is properly updated with the sg_chain invocation. During the filling-in of the initial SG entries, sg_mark_end is called for each SG entry. This is appropriate as long as no additional SGL is chained with the current SGL. However, when a new SGL is chained and the last SG entry is updated with sg_chain, the last but one entry still contains the end marker from the sg_mark_end. This end marker must be removed as otherwise a walk of the chained SGLs will cause a NULL pointer dereference at the last but one SG entry, because sg_next will return NULL. The patch only applies to all kernels up to and including 4.13. The patch 2d97591ef43d0587be22ad1b0d758d6df4999a0b added to 4.14-rc1 introduced a complete new code base which addresses this bug in a different way. Yet, that patch is too invasive for stable kernels and was therefore not marked for stable. Fixes: 8ff590903d5fc ("crypto: algif_skcipher - User-space interface for skcipher operations") Signed-off-by: Stephan Mueller <> Acked-by: Herbert Xu <> Signed-off-by: Greg Kroah-Hartman <>
1 files changed, 3 insertions, 1 deletions
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index b3b0004ea8ac..d12782dc9683 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -143,8 +143,10 @@ static int skcipher_alloc_sgl(struct sock *sk)
sg_init_table(sgl->sg, MAX_SGL_ENTS + 1);
sgl->cur = 0;
- if (sg)
+ if (sg) {
sg_chain(sg, MAX_SGL_ENTS + 1, sgl->sg);
+ sg_unmark_end(sg + (MAX_SGL_ENTS - 1));
+ }
list_add_tail(&sgl->list, &ctx->tsgl);