On Wed, Nov 09, 2022 at 10:16:58PM +0900, Taehee Yoo wrote:
>
> I have encountered kernel panic(stack-out-of-bounds) while using the reqctx
> instead of the tfm.
>
> cryptd is used when simd drivers are used.
> cryptd_skcipher_encrypt() internally doesn't allocate a request ctx of a
> child, instead, it uses stack memory with SYNC_SKCIPHER_REQUEST_ON_STACK.
> It retains only 384 bytes for child request ctx even if a child set a large
> reqsize value with crypto_skcipher_set_reqsize().
> aria-avx2 needs 512 bytes and aria-avx512 needs 1024 bytes.
> So, stack-out-of-bounds occurs.
OK this is not supposed to happen.
---8<---
cryptd is buggy as it tries to use sync_skcipher without going
through the proper sync_skcipher interface. In fact it doesn't
even need sync_skcipher since it's already a proper skcipher and
can easily access the request context instead of using something
off the stack.
Fixes: 36b3875a97b8 ("crypto: cryptd - Remove VLA usage of skcipher")
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index 668095eca0fa..ca3a40fc7da9 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -68,11 +68,12 @@ struct aead_instance_ctx {
struct cryptd_skcipher_ctx {
refcount_t refcnt;
- struct crypto_sync_skcipher *child;
+ struct crypto_skcipher *child;
};
struct cryptd_skcipher_request_ctx {
crypto_completion_t complete;
+ struct skcipher_request req;
};
struct cryptd_hash_ctx {
@@ -227,13 +228,13 @@ static int cryptd_skcipher_setkey(struct crypto_skcipher *parent,
const u8 *key, unsigned int keylen)
{
struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(parent);
- struct crypto_sync_skcipher *child = ctx->child;
+ struct crypto_skcipher *child = ctx->child;
- crypto_sync_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
- crypto_sync_skcipher_set_flags(child,
- crypto_skcipher_get_flags(parent) &
- CRYPTO_TFM_REQ_MASK);
- return crypto_sync_skcipher_setkey(child, key, keylen);
+ crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+ crypto_skcipher_set_flags(child,
+ crypto_skcipher_get_flags(parent) &
+ CRYPTO_TFM_REQ_MASK);
+ return crypto_skcipher_setkey(child, key, keylen);
}
static void cryptd_skcipher_complete(struct skcipher_request *req, int err)
@@ -258,13 +259,13 @@ static void cryptd_skcipher_encrypt(struct crypto_async_request *base,
struct cryptd_skcipher_request_ctx *rctx = skcipher_request_ctx(req);
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
- struct crypto_sync_skcipher *child = ctx->child;
- SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, child);
+ struct skcipher_request *subreq = &rctx->req;
+ struct crypto_skcipher *child = ctx->child;
if (unlikely(err == -EINPROGRESS))
goto out;
- skcipher_request_set_sync_tfm(subreq, child);
+ skcipher_request_set_tfm(subreq, child);
skcipher_request_set_callback(subreq, CRYPTO_TFM_REQ_MAY_SLEEP,
NULL, NULL);
skcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
@@ -286,13 +287,13 @@ static void cryptd_skcipher_decrypt(struct crypto_async_request *base,
struct cryptd_skcipher_request_ctx *rctx = skcipher_request_ctx(req);
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
- struct crypto_sync_skcipher *child = ctx->child;
- SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, child);
+ struct skcipher_request *subreq = &rctx->req;
+ struct crypto_skcipher *child = ctx->child;
if (unlikely(err == -EINPROGRESS))
goto out;
- skcipher_request_set_sync_tfm(subreq, child);
+ skcipher_request_set_tfm(subreq, child);
skcipher_request_set_callback(subreq, CRYPTO_TFM_REQ_MAY_SLEEP,
NULL, NULL);
skcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
@@ -343,9 +344,10 @@ static int cryptd_skcipher_init_tfm(struct crypto_skcipher *tfm)
if (IS_ERR(cipher))
return PTR_ERR(cipher);
- ctx->child = (struct crypto_sync_skcipher *)cipher;
+ ctx->child = cipher;
crypto_skcipher_set_reqsize(
- tfm, sizeof(struct cryptd_skcipher_request_ctx));
+ tfm, sizeof(struct cryptd_skcipher_request_ctx) +
+ crypto_skcipher_reqsize(cipher));
return 0;
}
@@ -353,7 +355,7 @@ static void cryptd_skcipher_exit_tfm(struct crypto_skcipher *tfm)
{
struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
- crypto_free_sync_skcipher(ctx->child);
+ crypto_free_skcipher(ctx->child);
}
static void cryptd_skcipher_free(struct skcipher_instance *inst)
@@ -931,7 +933,7 @@ struct crypto_skcipher *cryptd_skcipher_child(struct cryptd_skcipher *tfm)
{
struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(&tfm->base);
- return &ctx->child->base;
+ return ctx->child;
}
EXPORT_SYMBOL_GPL(cryptd_skcipher_child);
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
