From: Eric Biggers <ebiggers@xxxxxxxxxx>
gcmaes_crypt_by_sg() dereferences the NULL pointer returned by
scatterwalk_ffwd() when encrypting an empty plaintext and the source
scatterlist ends immediately after the associated data.
Fix it by only fast-forwarding to the src/dst data scatterlists if the
data length is nonzero.
This bug is reproduced by the "rfc4543(gcm(aes))" test vectors when run
with the new AEAD test manager.
Fixes: e845520707f8 ("crypto: aesni - Update aesni-intel_glue to use scatter/gather")
Cc: <stable@xxxxxxxxxxxxxxx> # v4.17+
Cc: Dave Watson <davejwatson@xxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
arch/x86/crypto/aesni-intel_glue.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index 9b5ccde3ef31..1e3d2102033a 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -813,11 +813,14 @@ static int gcmaes_crypt_by_sg(bool enc, struct aead_request *req,
scatterwalk_map_and_copy(assoc, req->src, 0, assoclen, 0);
}
- src_sg = scatterwalk_ffwd(src_start, req->src, req->assoclen);
- scatterwalk_start(&src_sg_walk, src_sg);
- if (req->src != req->dst) {
- dst_sg = scatterwalk_ffwd(dst_start, req->dst, req->assoclen);
- scatterwalk_start(&dst_sg_walk, dst_sg);
+ if (left) {
+ src_sg = scatterwalk_ffwd(src_start, req->src, req->assoclen);
+ scatterwalk_start(&src_sg_walk, src_sg);
+ if (req->src != req->dst) {
+ dst_sg = scatterwalk_ffwd(dst_start, req->dst,
+ req->assoclen);
+ scatterwalk_start(&dst_sg_walk, dst_sg);
+ }
}
kernel_fpu_begin();
--
2.20.1.321.g9e740568ce-goog
