3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit 318abdfbe708aaaa652c79fb500e9bd60521f9dc upstream.
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: Liu Chao liuchao741@huawei.com Fixes: bf06099db18a ("crypto: skcipher - Add ablkcipher_walk interfaces") Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Ben Hutchings ben@decadent.org.uk --- crypto/ablkcipher.c | 57 +++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 31 deletions(-)
--- a/crypto/ablkcipher.c +++ b/crypto/ablkcipher.c @@ -72,11 +72,9 @@ static inline u8 *ablkcipher_get_spot(u8 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);
@@ -88,17 +86,13 @@ static inline unsigned int ablkcipher_do n -= len_this_page; scatterwalk_start(&walk->out, scatterwalk_sg_next(walk->out.sg)); } - - return bsize; }
-static inline unsigned int ablkcipher_done_fast(struct ablkcipher_walk *walk, - unsigned int n) +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, @@ -108,39 +102,40 @@ int ablkcipher_walk_done(struct ablkciph 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)) { + n = walk->nbytes - err; + walk->total -= n; + more = (walk->total != 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 err; - } else - n = ablkcipher_done_slow(walk, n); - - nbytes = walk->total - n; - err = 0; + goto finish; + } + ablkcipher_done_slow(walk, n); }
- scatterwalk_done(&walk->in, 0, nbytes); - scatterwalk_done(&walk->out, 1, nbytes); + scatterwalk_done(&walk->in, 0, more); + scatterwalk_done(&walk->out, 1, more);
-err: - walk->total = nbytes; - walk->nbytes = nbytes; - - 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);