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authorEric Biggers <ebiggers@google.com>2017-11-28 20:56:59 -0800
committerHerbert Xu <herbert@gondor.apana.org.au>2017-11-29 16:25:58 +1100
commitecaaab5649781c5a0effdaf298a925063020500e (patch)
tree4b356fd0398dec802a7fc2cf7e41490e9ad76b65 /crypto
parentaf3ff8045bbf3e32f1a448542e73abb4c8ceb6f1 (diff)
download96b-common-ecaaab5649781c5a0effdaf298a925063020500e.tar.gz
crypto: salsa20 - fix blkcipher_walk API usage
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") Cc: <stable@vger.kernel.org> # v2.6.25+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/salsa20_generic.c7
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,