[CRYPTO] all: Check for usage in hard IRQ context

Using blkcipher/hash crypto operations in hard IRQ context can lead
to random memory corruption due to the reuse of kmap_atomic slots.
Since crypto operations were never meant to be used in hard IRQ
contexts, this patch checks for such usage and returns an error
before kmap_atomic is performed.

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

1 files changed, 16 insertions, 3 deletions

diff --git a/crypto/digest.c b/crypto/digest.c
index 8f45932..bc47af6 100644
--- a/crypto/digest.c
+++ b/crypto/digest.c
@@ -14,7 +14,9 @@
 
 #include <linux/mm.h>
 #include <linux/errno.h>
+#include <linux/hardirq.h>
 #include <linux/highmem.h>
+#include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 
@@ -29,8 +31,8 @@ static int init(struct hash_desc *desc)
 	return 0;
 }
 
-static int update(struct hash_desc *desc,
-		  struct scatterlist *sg, unsigned int nbytes)
+static int update2(struct hash_desc *desc,
+		   struct scatterlist *sg, unsigned int nbytes)
 {
 	struct crypto_tfm *tfm = crypto_hash_tfm(desc->tfm);
 	unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
@@ -81,6 +83,14 @@ static int update(struct hash_desc *desc,
 	return 0;
 }
 
+static int update(struct hash_desc *desc,
+		  struct scatterlist *sg, unsigned int nbytes)
+{
+	if (WARN_ON_ONCE(in_irq()))
+		return -EDEADLK;
+	return update2(desc, sg, nbytes);
+}
+
 static int final(struct hash_desc *desc, u8 *out)
 {
 	struct crypto_tfm *tfm = crypto_hash_tfm(desc->tfm);
@@ -118,8 +128,11 @@ static int setkey(struct crypto_hash *hash, const u8 *key, unsigned int keylen)
 static int digest(struct hash_desc *desc,
 		  struct scatterlist *sg, unsigned int nbytes, u8 *out)
 {
+	if (WARN_ON_ONCE(in_irq()))
+		return -EDEADLK;
+
 	init(desc);
-	update(desc, sg, nbytes);
+	update2(desc, sg, nbytes);
 	return final(desc, out);
 }