[PATCH 0/3] Fix crypto/vmx/p8_ghash memory corruption

@@ -26,16 +26,13 @@
 #include <linux/hardirq.h>
 #include <asm/switch_to.h>
 #include <crypto/aes.h>
+#include <crypto/ghash.h>
 #include <crypto/scatterwalk.h>
 #include <crypto/internal/hash.h>
 #include <crypto/b128ops.h>
 
 #define IN_INTERRUPT in_interrupt()
 
-#define GHASH_BLOCK_SIZE (16)
-#define GHASH_DIGEST_SIZE (16)
-#define GHASH_KEY_LEN (16)
-
 void gcm_init_p8(u128 htable[16], const u64 Xi[2]);
 void gcm_gmult_p8(u64 Xi[2], const u128 htable[16]);
 void gcm_ghash_p8(u64 Xi[2], const u128 htable[16],

@@ -55,16 +52,11 @@ struct p8_ghash_desc_ctx {
 
 static int p8_ghash_init_tfm(struct crypto_tfm *tfm)
 {
-	const char *alg;
+	const char *alg = "ghash-generic";
 	struct crypto_shash *fallback;
 	struct crypto_shash *shash_tfm = __crypto_shash_cast(tfm);
 	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(tfm);
 
-	if (!(alg = crypto_tfm_alg_name(tfm))) {
-		printk(KERN_ERR "Failed to get algorithm name.\n");
-		return -ENOENT;
-	}
-
 	fallback = crypto_alloc_shash(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
 	if (IS_ERR(fallback)) {
 		printk(KERN_ERR

@@ -78,10 +70,18 @@ static int p8_ghash_init_tfm(struct crypto_tfm *tfm)
 	crypto_shash_set_flags(fallback,
 			       crypto_shash_get_flags((struct crypto_shash
 						       *) tfm));
-	ctx->fallback = fallback;
 
-	shash_tfm->descsize = sizeof(struct p8_ghash_desc_ctx)
-	    + crypto_shash_descsize(fallback);
+	/* Check if the descsize defined in the algorithm is still enough. */
+	if (shash_tfm->descsize < sizeof(struct p8_ghash_desc_ctx)
+	    + crypto_shash_descsize(fallback)) {
+		printk(KERN_ERR
+		       "Desc size of the fallback implementation (%s) does not match the expected value: %lu vs %u\n",
+		       alg,
+		       shash_tfm->descsize - sizeof(struct p8_ghash_desc_ctx),
+		       crypto_shash_descsize(fallback));
+		return -EINVAL;
+	}
+	ctx->fallback = fallback;
 
 	return 0;
 }

@@ -113,7 +113,7 @@ static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
 {
 	struct p8_ghash_ctx *ctx = crypto_tfm_ctx(crypto_shash_tfm(tfm));
 
-	if (keylen != GHASH_KEY_LEN)
+	if (keylen != GHASH_BLOCK_SIZE)
 		return -EINVAL;
 
 	preempt_disable();

@@ -211,7 +211,8 @@ struct shash_alg p8_ghash_alg = {
 	.update = p8_ghash_update,
 	.final = p8_ghash_final,
 	.setkey = p8_ghash_setkey,
-	.descsize = sizeof(struct p8_ghash_desc_ctx),
+	.descsize = sizeof(struct p8_ghash_desc_ctx)
+		+ sizeof(struct ghash_desc_ctx),
 	.base = {
 		 .cra_name = "ghash",
 		 .cra_driver_name = "p8_ghash",

@@ -14,24 +14,13 @@
 
 #include <crypto/algapi.h>
 #include <crypto/gf128mul.h>
+#include <crypto/ghash.h>
 #include <crypto/internal/hash.h>
 #include <linux/crypto.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 
-#define GHASH_BLOCK_SIZE	16
-#define GHASH_DIGEST_SIZE	16
-
-struct ghash_ctx {
-	struct gf128mul_4k *gf128;
-};
-
-struct ghash_desc_ctx {
-	u8 buffer[GHASH_BLOCK_SIZE];
-	u32 bytes;
-};
-
 static int ghash_init(struct shash_desc *desc)
 {
 	struct ghash_desc_ctx *dctx = shash_desc_ctx(desc);

@@ -0,0 +1,23 @@
+/*
+ * Common values for GHASH algorithms
+ */
+
+#ifndef __CRYPTO_GHASH_H__
+#define __CRYPTO_GHASH_H__
+
+#include <linux/types.h>
+#include <crypto/gf128mul.h>
+
+#define GHASH_BLOCK_SIZE	16
+#define GHASH_DIGEST_SIZE	16
+
+struct ghash_ctx {
+	struct gf128mul_4k *gf128;
+};
+
+struct ghash_desc_ctx {
+	u8 buffer[GHASH_BLOCK_SIZE];
+	u32 bytes;
+};
+
+#endif

@@ -1,6 +1,6 @@
 config CRYPTO_DEV_VMX_ENCRYPT
 	tristate "Encryption acceleration support on P8 CPU"
-	depends on CRYPTO_DEV_VMX
+	depends on CRYPTO_DEV_VMX || CRYPTO_GHASH
 	default m
 	help
 	  Support for VMX cryptographic acceleration instructions on Power8 CPU.