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authorStephan Mueller <smueller@chronox.de>2015-03-12 09:17:51 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-26 15:01:00 +0100
commit31c06b946ce68c0792288f456f0e57e45c19b322 (patch)
treeafe6784dd3fc80a79f393ebcefb9fbd5b286c32f
parente2e35381f37b4d110add16aa2ca52a19801219c4 (diff)
downloadlinux-linaro-stable-31c06b946ce68c0792288f456f0e57e45c19b322.tar.gz
crypto: aesni - fix memory usage in GCM decryption
commit ccfe8c3f7e52ae83155cb038753f4c75b774ca8a upstream. The kernel crypto API logic requires the caller to provide the length of (ciphertext || authentication tag) as cryptlen for the AEAD decryption operation. Thus, the cipher implementation must calculate the size of the plaintext output itself and cannot simply use cryptlen. The RFC4106 GCM decryption operation tries to overwrite cryptlen memory in req->dst. As the destination buffer for decryption only needs to hold the plaintext memory but cryptlen references the input buffer holding (ciphertext || authentication tag), the assumption of the destination buffer length in RFC4106 GCM operation leads to a too large size. This patch simply uses the already calculated plaintext size. In addition, this patch fixes the offset calculation of the AAD buffer pointer: as mentioned before, cryptlen already includes the size of the tag. Thus, the tag does not need to be added. With the addition, the AAD will be written beyond the already allocated buffer. Note, this fixes a kernel crash that can be triggered from user space via AF_ALG(aead) -- simply use the libkcapi test application from [1] and update it to use rfc4106-gcm-aes. Using [1], the changes were tested using CAVS vectors to demonstrate that the crypto operation still delivers the right results. [1] http://www.chronox.de/libkcapi.html CC: Tadeusz Struk <tadeusz.struk@intel.com> 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>
-rw-r--r--arch/x86/crypto/aesni-intel_glue.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index f89e7490d303..990c9699b662 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -989,7 +989,7 @@ static int __driver_rfc4106_decrypt(struct aead_request *req)
src = kmalloc(req->cryptlen + req->assoclen, GFP_ATOMIC);
if (!src)
return -ENOMEM;
- assoc = (src + req->cryptlen + auth_tag_len);
+ assoc = (src + req->cryptlen);
scatterwalk_map_and_copy(src, req->src, 0, req->cryptlen, 0);
scatterwalk_map_and_copy(assoc, req->assoc, 0,
req->assoclen, 0);
@@ -1014,7 +1014,7 @@ static int __driver_rfc4106_decrypt(struct aead_request *req)
scatterwalk_done(&src_sg_walk, 0, 0);
scatterwalk_done(&assoc_sg_walk, 0, 0);
} else {
- scatterwalk_map_and_copy(dst, req->dst, 0, req->cryptlen, 1);
+ scatterwalk_map_and_copy(dst, req->dst, 0, tempCipherLen, 1);
kfree(src);
}
return retval;