This is a note to let you know that I've just added the patch titled
crypto: aesni - fix memory usage in GCM decryption
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
crypto-aesni-fix-memory-usage-in-gcm-decryption.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From ccfe8c3f7e52ae83155cb038753f4c75b774ca8a Mon Sep 17 00:00:00 2001
From: Stephan Mueller <[email protected]>
Date: Thu, 12 Mar 2015 09:17:51 +0100
Subject: crypto: aesni - fix memory usage in GCM decryption
From: Stephan Mueller <[email protected]>
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 <[email protected]>
Signed-off-by: Stephan Mueller <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/crypto/aesni-intel_glue.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- 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(stru
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(stru
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;
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/crypto-aesni-fix-memory-usage-in-gcm-decryption.patch
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