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authorKees Cook <keescook@chromium.org>2018-04-10 17:52:34 -0700
committerDavid S. Miller <davem@davemloft.net>2018-04-12 21:46:10 -0400
commitb16520f7493d06d8ef6d4255bdfcf7a803d7874a (patch)
treeb3ef990644cc23ce82112531b9737a7618e7d97e /net
parent08ea556e14b56e9a49b19abd8e39f0c9e05582f2 (diff)
downloadlinux-b16520f7493d06d8ef6d4255bdfcf7a803d7874a.tar.bz2
net/tls: Remove VLA usage
In the quest to remove VLAs from the kernel[1], this replaces the VLA size with the only possible size used in the code, and adds a mechanism to double-check future IV sizes. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Dave Watson <davejwatson@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/tls/tls_sw.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 4dc766b03f00..71e79597f940 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -41,6 +41,8 @@
#include <net/strparser.h>
#include <net/tls.h>
+#define MAX_IV_SIZE TLS_CIPHER_AES_GCM_128_IV_SIZE
+
static int tls_do_decryption(struct sock *sk,
struct scatterlist *sgin,
struct scatterlist *sgout,
@@ -673,7 +675,7 @@ static int decrypt_skb(struct sock *sk, struct sk_buff *skb,
{
struct tls_context *tls_ctx = tls_get_ctx(sk);
struct tls_sw_context *ctx = tls_sw_ctx(tls_ctx);
- char iv[TLS_CIPHER_AES_GCM_128_SALT_SIZE + tls_ctx->rx.iv_size];
+ char iv[TLS_CIPHER_AES_GCM_128_SALT_SIZE + MAX_IV_SIZE];
struct scatterlist sgin_arr[MAX_SKB_FRAGS + 2];
struct scatterlist *sgin = &sgin_arr[0];
struct strp_msg *rxm = strp_msg(skb);
@@ -1094,6 +1096,12 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
goto free_priv;
}
+ /* Sanity-check the IV size for stack allocations. */
+ if (iv_size > MAX_IV_SIZE) {
+ rc = -EINVAL;
+ goto free_priv;
+ }
+
cctx->prepend_size = TLS_HEADER_SIZE + nonce_size;
cctx->tag_size = tag_size;
cctx->overhead_size = cctx->prepend_size + cctx->tag_size;