crypto: hash - Fix page length clamping in hash walk

Commit Message

Herbert Xu May 3, 2016, 9:55 a.m. UTC

On Thu, Apr 28, 2016 at 10:27:43AM +0200, Steffen Klassert wrote:
>
> The problem was that if offset (in a superpage) equals
> PAGE_SIZE in hash_walk_next(), nbytes becomes zero. So
> we map the page, but we don't hash and unmap because we
> exit the loop in shash_ahash_update() in this case.

I see.  Does this patch help?

---8<---
The length clamping in the crypto hash walk code is broken if
supplied with an offset greater than or equal to PAGE_SIZE.  This
patch fixes it by borrowing the code from scatterwalk.

Cc: <[e-mail]>
Reported-by: Steffen Klassert <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

Comments

Steffen Klassert May 4, 2016, 9:34 a.m. UTC | #1

On Tue, May 03, 2016 at 05:55:31PM +0800, Herbert Xu wrote:
> On Thu, Apr 28, 2016 at 10:27:43AM +0200, Steffen Klassert wrote:
> >
> > The problem was that if offset (in a superpage) equals
> > PAGE_SIZE in hash_walk_next(), nbytes becomes zero. So
> > we map the page, but we don't hash and unmap because we
> > exit the loop in shash_ahash_update() in this case.
> 
> I see.  Does this patch help?

Hmm, the 'sleeping while atomic' because of not unmapping
the page goes away, but now I see a lot of IPsec ICV fails
on the receive side. I'll try to find out what's going on.

Sowmini, could you please doublecheck with your test setup?

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Patch

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 5fc1f17..2d6c4f1 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -44,8 +44,8 @@  static int hash_walk_next(struct crypto_hash_walk *walk)
 {
 	unsigned int alignmask = walk->alignmask;
 	unsigned int offset = walk->offset;
-	unsigned int nbytes = min(walk->entrylen,
-				  ((unsigned int)(PAGE_SIZE)) - offset);
+	unsigned int nbytes = min_t(unsigned int, walk->entrylen,
+				    offset_in_page(~offset) + 1);
 
 	if (walk->flags & CRYPTO_ALG_ASYNC)
 		walk->data = kmap(walk->pg);
@@ -91,8 +91,8 @@  int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
 		walk->offset = ALIGN(walk->offset, alignmask + 1);
 		walk->data += walk->offset;
 
-		nbytes = min(nbytes,
-			     ((unsigned int)(PAGE_SIZE)) - walk->offset);
+		nbytes = min_t(unsigned int, nbytes,
+			       offset_in_page(~walk->offset) + 1);
 		walk->entrylen -= nbytes;
 
 		return nbytes;