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crypto: algif_skcipher - Require setkey before accept(2)

Some cipher implementations will crash if you try to use them
without calling setkey first.  This patch adds a check so that
the accept(2) call will fail with -ENOKEY if setkey hasn't been
done on the socket yet.

Reported-by: Dmitry Vyukov <>
Signed-off-by: Herbert Xu <>
Tested-by: Dmitry Vyukov <>
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herbertx committed Dec 25, 2015
1 parent c597b6b commit dd504589577d8e8e70f51f997ad487a4cb6c026f
Showing with 41 additions and 7 deletions.
  1. +41 −7 crypto/algif_skcipher.c
@@ -31,6 +31,11 @@ struct skcipher_sg_list {
struct scatterlist sg[0];

struct skcipher_tfm {
struct crypto_skcipher *skcipher;
bool has_key;

struct skcipher_ctx {
struct list_head tsgl;
struct af_alg_sgl rsgl;
@@ -750,17 +755,41 @@ static struct proto_ops algif_skcipher_ops = {

static void *skcipher_bind(const char *name, u32 type, u32 mask)
return crypto_alloc_skcipher(name, type, mask);
struct skcipher_tfm *tfm;
struct crypto_skcipher *skcipher;

tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
if (!tfm)
return ERR_PTR(-ENOMEM);

skcipher = crypto_alloc_skcipher(name, type, mask);
if (IS_ERR(skcipher)) {
return ERR_CAST(skcipher);

tfm->skcipher = skcipher;

return tfm;

static void skcipher_release(void *private)
struct skcipher_tfm *tfm = private;


static int skcipher_setkey(void *private, const u8 *key, unsigned int keylen)
return crypto_skcipher_setkey(private, key, keylen);
struct skcipher_tfm *tfm = private;
int err;

err = crypto_skcipher_setkey(tfm->skcipher, key, keylen);
tfm->has_key = !err;

return err;

static void skcipher_wait(struct sock *sk)
@@ -792,20 +821,25 @@ static int skcipher_accept_parent(void *private, struct sock *sk)
struct skcipher_ctx *ctx;
struct alg_sock *ask = alg_sk(sk);
unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(private);
struct skcipher_tfm *tfm = private;
struct crypto_skcipher *skcipher = tfm->skcipher;
unsigned int len = sizeof(*ctx) + crypto_skcipher_reqsize(skcipher);

if (!tfm->has_key)
return -ENOKEY;

ctx = sock_kmalloc(sk, len, GFP_KERNEL);
if (!ctx)
return -ENOMEM;

ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(private),
ctx->iv = sock_kmalloc(sk, crypto_skcipher_ivsize(skcipher),
if (!ctx->iv) {
sock_kfree_s(sk, ctx, len);
return -ENOMEM;

memset(ctx->iv, 0, crypto_skcipher_ivsize(private));
memset(ctx->iv, 0, crypto_skcipher_ivsize(skcipher));

ctx->len = len;
@@ -818,7 +852,7 @@ static int skcipher_accept_parent(void *private, struct sock *sk)

ask->private = ctx;

skcipher_request_set_tfm(&ctx->req, private);
skcipher_request_set_tfm(&ctx->req, skcipher);
skcipher_request_set_callback(&ctx->req, CRYPTO_TFM_REQ_MAY_BACKLOG,
af_alg_complete, &ctx->completion);

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