4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
commit 0868def3e4100591e7a1fdbf3eed1439cc8f7ca3 upstream.
Like the skcipher_walk case:
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 blkcipher_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 blkcipher_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 = "ecb(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: 5cde0af2a982 ("[CRYPTO] cipher: Added block cipher type") Cc: stable@vger.kernel.org # v2.6.19+ Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- crypto/blkcipher.c | 54 +++++++++++++++++++++++++---------------------------- 1 file changed, 26 insertions(+), 28 deletions(-)
--- a/crypto/blkcipher.c +++ b/crypto/blkcipher.c @@ -71,19 +71,18 @@ static inline u8 *blkcipher_get_spot(u8 return max(start, end_page); }
-static inline unsigned int blkcipher_done_slow(struct blkcipher_walk *walk, - unsigned int bsize) +static inline void blkcipher_done_slow(struct blkcipher_walk *walk, + unsigned int bsize) { u8 *addr;
addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1); addr = blkcipher_get_spot(addr, bsize); scatterwalk_copychunks(addr, &walk->out, bsize, 1); - return bsize; }
-static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk, - unsigned int n) +static inline void blkcipher_done_fast(struct blkcipher_walk *walk, + unsigned int n) { if (walk->flags & BLKCIPHER_WALK_COPY) { blkcipher_map_dst(walk); @@ -97,49 +96,48 @@ static inline unsigned int blkcipher_don
scatterwalk_advance(&walk->in, n); scatterwalk_advance(&walk->out, n); - - return n; }
int blkcipher_walk_done(struct blkcipher_desc *desc, struct blkcipher_walk *walk, int err) { - 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 & BLKCIPHER_WALK_SLOW))) - n = blkcipher_done_fast(walk, n); - else if (WARN_ON(err)) { + n = walk->nbytes - err; + walk->total -= n; + more = (walk->total != 0); + + if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW))) { + blkcipher_done_fast(walk, n); + } else { + if (WARN_ON(err)) { + /* unexpected case; didn't process all bytes */ err = -EINVAL; - goto err; - } else - n = blkcipher_done_slow(walk, n); - - nbytes = walk->total - n; - err = 0; + goto finish; + } + blkcipher_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(desc->flags); return blkcipher_walk_next(desc, walk); } - + err = 0; +finish: + walk->nbytes = 0; if (walk->iv != desc->info) memcpy(desc->info, walk->iv, walk->ivsize); if (walk->buffer != walk->page) kfree(walk->buffer); if (walk->page) free_page((unsigned long)walk->page); - return err; } EXPORT_SYMBOL_GPL(blkcipher_walk_done);