Commit 318abdfb authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: ablkcipher - fix crash flushing dcache in error path 



Like the skcipher_walk and blkcipher_walk cases:

scatterwalk_done() is only meant to be called after a nonzero number of
bytes have been processed, since scatterwalk_pagedone() will flush the
dcache of the *previous* page.  But in the error case of
ablkcipher_walk_done(), e.g. if the input wasn't an integer number of
blocks, scatterwalk_done() was actually called after advancing 0 bytes.
This caused a crash ("BUG: unable to handle kernel paging request")
during '!PageSlab(page)' on architectures like arm and arm64 that define
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE, provided that the input was
page-aligned as in that case walk->offset == 0.

Fix it by reorganizing ablkcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.

Reported-by: default avatarLiu Chao <liuchao741@huawei.com>
Fixes: bf06099d ("crypto: skcipher - Add ablkcipher_walk interfaces")
Cc: <stable@vger.kernel.org> # v2.6.35+
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 0868def3

crypto/ablkcipher.c

+26 −31
Original line number Diff line number Diff line
@@ -71,11 +71,9 @@ static inline u8 *ablkcipher_get_spot(u8 *start, unsigned int len) 
	return max(start, end_page);

}



static inline unsigned int ablkcipher_done_slow(struct ablkcipher_walk *walk,

						unsigned int bsize)

static inline void ablkcipher_done_slow(struct ablkcipher_walk *walk,

					unsigned int n)

{

	unsigned int n = bsize;



	for (;;) {

		unsigned int len_this_page = scatterwalk_pagelen(&walk->out);
@@ -87,17 +85,13 @@ static inline unsigned int ablkcipher_done_slow(struct ablkcipher_walk *walk, 
		n -= len_this_page;

		scatterwalk_start(&walk->out, sg_next(walk->out.sg));

	}



	return bsize;

}



static inline unsigned int ablkcipher_done_fast(struct ablkcipher_walk *walk,

static inline void ablkcipher_done_fast(struct ablkcipher_walk *walk,

					unsigned int n)

{

	scatterwalk_advance(&walk->in, n);

	scatterwalk_advance(&walk->out, n);



	return n;

}



static int ablkcipher_walk_next(struct ablkcipher_request *req,
@@ -107,39 +101,40 @@ int ablkcipher_walk_done(struct ablkcipher_request *req, 
			 struct ablkcipher_walk *walk, int err)

{

	struct crypto_tfm *tfm = req->base.tfm;

	unsigned int nbytes = 0;

	unsigned int n; /* bytes processed */

	bool more;



	if (likely(err >= 0)) {

		unsigned int n = walk->nbytes - err;

	if (unlikely(err < 0))

		goto finish;



		if (likely(!(walk->flags & ABLKCIPHER_WALK_SLOW)))

			n = ablkcipher_done_fast(walk, n);

		else if (WARN_ON(err)) {

			err = -EINVAL;

			goto err;

		} else

			n = ablkcipher_done_slow(walk, n);

	n = walk->nbytes - err;

	walk->total -= n;

	more = (walk->total != 0);



		nbytes = walk->total - n;

		err = 0;

	if (likely(!(walk->flags & ABLKCIPHER_WALK_SLOW))) {

		ablkcipher_done_fast(walk, n);

	} else {

		if (WARN_ON(err)) {

			/* unexpected case; didn't process all bytes */

			err = -EINVAL;

			goto finish;

		}

		ablkcipher_done_slow(walk, n);

	}



	scatterwalk_done(&walk->in, 0, nbytes);

	scatterwalk_done(&walk->out, 1, nbytes);



err:

	walk->total = nbytes;

	walk->nbytes = nbytes;

	scatterwalk_done(&walk->in, 0, more);

	scatterwalk_done(&walk->out, 1, more);



	if (nbytes) {

	if (more) {

		crypto_yield(req->base.flags);

		return ablkcipher_walk_next(req, walk);

	}



	err = 0;

finish:

	walk->nbytes = 0;

	if (walk->iv != req->info)

		memcpy(req->info, walk->iv, tfm->crt_ablkcipher.ivsize);

	kfree(walk->iv_buffer);



	return err;

}

EXPORT_SYMBOL_GPL(ablkcipher_walk_done);

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