[CRYPTO] digest: Store temporary digest in tfm

When the final result location is unaligned, we store the digest in a
temporary buffer before copying it to the final location.  Currently
that buffer sits on the stack.  This patch moves it to an area in the
tfm, just like the CBC IV buffer.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 18 insertions, 7 deletions

diff --git a/crypto/digest.c b/crypto/digest.c
index 0df7f392a56a..19e75563776b 100644
--- a/crypto/digest.c
+++ b/crypto/digest.c
@@ -66,14 +66,18 @@ static void update(struct crypto_tfm *tfm,
 static void final(struct crypto_tfm *tfm, u8 *out)
 {
         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
+        struct digest_alg *digest = &tfm->__crt_alg->cra_digest;
+
         if (unlikely((unsigned long)out & alignmask)) {
-                unsigned int size = crypto_tfm_alg_digestsize(tfm);
-                u8 buffer[size + alignmask];
-                u8 *dst = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
-                tfm->__crt_alg->cra_digest.dia_final(tfm, dst);
-                memcpy(out, dst, size);
+                unsigned long align = alignmask + 1;
+                unsigned long addr = (unsigned long)crypto_tfm_ctx(tfm);
+                u8 *dst = (u8 *)ALIGN(addr, align) +
+                          ALIGN(tfm->__crt_alg->cra_ctxsize, align);
+
+                digest->dia_final(tfm, dst);
+                memcpy(out, dst, digest->dia_digestsize);
         } else
-                tfm->__crt_alg->cra_digest.dia_final(tfm, out);
+                digest->dia_final(tfm, out);
 }
 
 static int nosetkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
diff --git a/crypto/internal.h b/crypto/internal.h
index 03c00b0e6b60..b110b979b988 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -99,7 +99,14 @@ static inline void crypto_exit_proc(void)
 static inline unsigned int crypto_digest_ctxsize(struct crypto_alg *alg,
                                                  int flags)
 {
-        return alg->cra_ctxsize;
+        unsigned int len = alg->cra_ctxsize;
+
+        if (alg->cra_alignmask) {
+                len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
+                len += alg->cra_digest.dia_digestsize;
+        }
+
+        return len;
 }
 
 static inline unsigned int crypto_cipher_ctxsize(struct crypto_alg *alg,