crypto: arm64/aes-neonbs - Move key expansion off the stack

aesbs_setkey() and aesbs_cbc_ctr_setkey() allocate struct crypto_aes_ctx
on the stack. On arm64, the kernel-mode NEON context is also stored on
the stack, causing the combined frame size to exceed 1024 bytes and
triggering -Wframe-larger-than= warnings.

Allocate struct crypto_aes_ctx on the heap instead and use
kfree_sensitive() to ensure the key material is zeroed on free.
Use a goto-based cleanup path to ensure kfree_sensitive() is always
called.

Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Fixes: 4fa617cc6851 ("arm64/fpsimd: Allocate kernel mode FP/SIMD buffers on the stack")
Link: https://lore.kernel.org/r/20260306064254.2079274-1-yphbchou0911@gmail.com
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

diff --git a/arch/arm64/crypto/aes-neonbs-glue.c b/arch/arm64/crypto/aes-neonbs-glue.c
index cb87c8fc66b3b056ff4dde39d974c786253f4713..00530b29101023b56d472c73886ec3d0d86c501e 100644 (file)
--- a/arch/arm64/crypto/aes-neonbs-glue.c
+++ b/arch/arm64/crypto/aes-neonbs-glue.c
@@ -76,19 +76,24 @@ static int aesbs_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
                        unsigned int key_len)
 {
        struct aesbs_ctx *ctx = crypto_skcipher_ctx(tfm);
-       struct crypto_aes_ctx rk;
+       struct crypto_aes_ctx *rk;
        int err;
 
-       err = aes_expandkey(&rk, in_key, key_len);
+       rk = kmalloc(sizeof(*rk), GFP_KERNEL);
+       if (!rk)
+               return -ENOMEM;
+
+       err = aes_expandkey(rk, in_key, key_len);
        if (err)
-               return err;
+               goto out;
 
        ctx->rounds = 6 + key_len / 4;
 
        scoped_ksimd()
-               aesbs_convert_key(ctx->rk, rk.key_enc, ctx->rounds);
-
-       return 0;
+               aesbs_convert_key(ctx->rk, rk->key_enc, ctx->rounds);
+out:
+       kfree_sensitive(rk);
+       return err;
 }
 
 static int __ecb_crypt(struct skcipher_request *req,
@@ -133,22 +138,26 @@ static int aesbs_cbc_ctr_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
                            unsigned int key_len)
 {
        struct aesbs_cbc_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
-       struct crypto_aes_ctx rk;
+       struct crypto_aes_ctx *rk;
        int err;
 
-       err = aes_expandkey(&rk, in_key, key_len);
+       rk = kmalloc(sizeof(*rk), GFP_KERNEL);
+       if (!rk)
+               return -ENOMEM;
+
+       err = aes_expandkey(rk, in_key, key_len);
        if (err)
-               return err;
+               goto out;
 
        ctx->key.rounds = 6 + key_len / 4;
 
-       memcpy(ctx->enc, rk.key_enc, sizeof(ctx->enc));
+       memcpy(ctx->enc, rk->key_enc, sizeof(ctx->enc));
 
        scoped_ksimd()
-               aesbs_convert_key(ctx->key.rk, rk.key_enc, ctx->key.rounds);
-       memzero_explicit(&rk, sizeof(rk));
-
-       return 0;
+               aesbs_convert_key(ctx->key.rk, rk->key_enc, ctx->key.rounds);
+out:
+       kfree_sensitive(rk);
+       return err;
 }
 
 static int cbc_encrypt(struct skcipher_request *req)