From 318abdfbe708aaaa652c79fb500e9bd60521f9dc Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 23 Jul 2018 10:54:58 -0700 Subject: [PATCH] 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: Liu Chao Fixes: bf06099db18a ("crypto: skcipher - Add ablkcipher_walk interfaces") Cc: # v2.6.35+ Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- crypto/ablkcipher.c | 57 +++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 31 deletions(-) diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c index 1edb5000d783..8882e90e868e 100644 --- a/crypto/ablkcipher.c +++ b/crypto/ablkcipher.c @@ -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, - 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, @@ -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)) { + 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);