4.4-stable review patch. If anyone has any objections, please let me know.
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From: Stephan Mueller smueller@chronox.de
commit 9c674e1e2f9e24fa4392167efe343749008338e0 upstream.
GCM can be invoked with a zero destination buffer. This is possible if the AAD and the ciphertext have zero lengths and only the tag exists in the source buffer (i.e. a source buffer cannot be zero). In this case, the GCM cipher only performs the authentication and no decryption operation.
When the destination buffer has zero length, it is possible that no page is mapped to the SG pointing to the destination. In this case, sg_page(req->dst) is an invalid access. Therefore, page accesses should only be allowed if the req->dst->length is non-zero which is the indicator that a page must exist.
This fixes a crash that can be triggered by user space via AF_ALG.
Signed-off-by: Stephan Mueller smueller@chronox.de Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/crypto/aesni-intel_glue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/crypto/aesni-intel_glue.c +++ b/arch/x86/crypto/aesni-intel_glue.c @@ -965,7 +965,7 @@ static int helper_rfc4106_encrypt(struct
if (sg_is_last(req->src) && req->src->offset + req->src->length <= PAGE_SIZE && - sg_is_last(req->dst) && + sg_is_last(req->dst) && req->dst->length && req->dst->offset + req->dst->length <= PAGE_SIZE) { one_entry_in_sg = 1; scatterwalk_start(&src_sg_walk, req->src);