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| author | Eric Biggers <ebiggers@google.com> | 2017-11-28 20:56:59 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-20 10:04:51 +0100 |
| commit | 8a311b0462b59d12cb14e82e626d3612d988135b (patch) | |
| tree | 0d9ed6e247621d1f5c57bfb9cf7d4b2c94087204 /crypto/salsa20_generic.c | |
| parent | 43cd7f38612df31fbd929588c065cfbc42102aab (diff) | |
| download | linux-stable-8a311b0462b59d12cb14e82e626d3612d988135b.tar.gz linux-stable-8a311b0462b59d12cb14e82e626d3612d988135b.tar.bz2 linux-stable-8a311b0462b59d12cb14e82e626d3612d988135b.zip | |
crypto: salsa20 - fix blkcipher_walk API usage
commit ecaaab5649781c5a0effdaf298a925063020500e upstream.
When asked to encrypt or decrypt 0 bytes, both the generic and x86
implementations of Salsa20 crash in blkcipher_walk_done(), either when
doing 'kfree(walk->buffer)' or 'free_page((unsigned long)walk->page)',
because walk->buffer and walk->page have not been initialized.
The bug is that Salsa20 is calling blkcipher_walk_done() even when
nothing is in 'walk.nbytes'. But blkcipher_walk_done() is only meant to
be called when a nonzero number of bytes have been provided.
The broken code is part of an optimization that tries to make only one
call to salsa20_encrypt_bytes() to process inputs that are not evenly
divisible by 64 bytes. To fix the bug, just remove this "optimization"
and use the blkcipher_walk API the same way all the other users do.
Reproducer:
#include <linux/if_alg.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
int algfd, reqfd;
struct sockaddr_alg addr = {
.salg_type = "skcipher",
.salg_name = "salsa20",
};
char key[16] = { 0 };
algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(algfd, (void *)&addr, sizeof(addr));
reqfd = accept(algfd, 0, 0);
setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key));
read(reqfd, key, sizeof(key));
}
Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: eb6f13eb9f81 ("[CRYPTO] salsa20_generic: Fix multi-page processing")
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>
Diffstat (limited to 'crypto/salsa20_generic.c')
| -rw-r--r-- | crypto/salsa20_generic.c | 7 |
1 files changed, 0 insertions, 7 deletions
diff --git a/crypto/salsa20_generic.c b/crypto/salsa20_generic.c index f550b5d94630..d7da0eea5622 100644 --- a/crypto/salsa20_generic.c +++ b/crypto/salsa20_generic.c @@ -188,13 +188,6 @@ static int encrypt(struct blkcipher_desc *desc, salsa20_ivsetup(ctx, walk.iv); - if (likely(walk.nbytes == nbytes)) - { - salsa20_encrypt_bytes(ctx, walk.dst.virt.addr, - walk.src.virt.addr, nbytes); - return blkcipher_walk_done(desc, &walk, 0); - } - while (walk.nbytes >= 64) { salsa20_encrypt_bytes(ctx, walk.dst.virt.addr, walk.src.virt.addr, |