diff options
author | Eric Biggers <ebiggers@google.com> | 2018-07-23 10:54:56 -0700 |
---|---|---|
committer | Herbert Xu <herbert@gondor.apana.org.au> | 2018-08-03 18:06:04 +0800 |
commit | 8088d3dd4d7c6933a65aa169393b5d88d8065672 (patch) | |
tree | 454df41eb17db574cc8fa89883678599e69ebcdf /crypto/skcipher.c | |
parent | 2a57c0be225f8c7140f8791819f5afbb6fb34c5a (diff) |
crypto: skcipher - fix crash flushing dcache in error path
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
skcipher_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 skcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.
This bug was found by syzkaller fuzzing.
Reproducer, assuming ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE:
#include <linux/if_alg.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
struct sockaddr_alg addr = {
.salg_type = "skcipher",
.salg_name = "cbc(aes-generic)",
};
char buffer[4096] __attribute__((aligned(4096))) = { 0 };
int fd;
fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(fd, (void *)&addr, sizeof(addr));
setsockopt(fd, SOL_ALG, ALG_SET_KEY, buffer, 16);
fd = accept(fd, NULL, NULL);
write(fd, buffer, 15);
read(fd, buffer, 15);
}
Reported-by: Liu Chao <liuchao741@huawei.com>
Fixes: b286d8b1a690 ("crypto: skcipher - Add skcipher walk interface")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/skcipher.c')
-rw-r--r-- | crypto/skcipher.c | 53 |
1 files changed, 27 insertions, 26 deletions
diff --git a/crypto/skcipher.c b/crypto/skcipher.c index 835e5d36ad59..0bd8c6caa498 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -95,7 +95,7 @@ static inline u8 *skcipher_get_spot(u8 *start, unsigned int len) return max(start, end_page); } -static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) +static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) { u8 *addr; @@ -103,23 +103,24 @@ static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) addr = skcipher_get_spot(addr, bsize); scatterwalk_copychunks(addr, &walk->out, bsize, (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1); - return 0; } int skcipher_walk_done(struct skcipher_walk *walk, int err) { - unsigned int n = walk->nbytes - err; - unsigned int nbytes; - - nbytes = walk->total - n; - - if (unlikely(err < 0)) { - nbytes = 0; - n = 0; - } else if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS | - SKCIPHER_WALK_SLOW | - SKCIPHER_WALK_COPY | - SKCIPHER_WALK_DIFF)))) { + unsigned int n; /* bytes processed */ + bool more; + + if (unlikely(err < 0)) + goto finish; + + n = walk->nbytes - err; + walk->total -= n; + more = (walk->total != 0); + + if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS | + SKCIPHER_WALK_SLOW | + SKCIPHER_WALK_COPY | + SKCIPHER_WALK_DIFF)))) { unmap_src: skcipher_unmap_src(walk); } else if (walk->flags & SKCIPHER_WALK_DIFF) { @@ -131,28 +132,28 @@ unmap_src: skcipher_unmap_dst(walk); } else if (unlikely(walk->flags & SKCIPHER_WALK_SLOW)) { if (WARN_ON(err)) { + /* unexpected case; didn't process all bytes */ err = -EINVAL; - nbytes = 0; - } else - n = skcipher_done_slow(walk, n); + goto finish; + } + skcipher_done_slow(walk, n); + goto already_advanced; } - if (err > 0) - err = 0; - - walk->total = nbytes; - walk->nbytes = nbytes; - scatterwalk_advance(&walk->in, n); scatterwalk_advance(&walk->out, n); - scatterwalk_done(&walk->in, 0, nbytes); - scatterwalk_done(&walk->out, 1, nbytes); +already_advanced: + scatterwalk_done(&walk->in, 0, more); + scatterwalk_done(&walk->out, 1, more); - if (nbytes) { + if (more) { crypto_yield(walk->flags & SKCIPHER_WALK_SLEEP ? CRYPTO_TFM_REQ_MAY_SLEEP : 0); return skcipher_walk_next(walk); } + err = 0; +finish: + walk->nbytes = 0; /* Short-circuit for the common/fast path. */ if (!((unsigned long)walk->buffer | (unsigned long)walk->page)) |