This is a note to let you know that I've just added the patch titled
crypto: salsa20 - fix blkcipher_walk API usage
to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: crypto-salsa20-fix-blkcipher_walk-api-usage.patch and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From ecaaab5649781c5a0effdaf298a925063020500e Mon Sep 17 00:00:00 2001
From: Eric Biggers ebiggers@google.com Date: Tue, 28 Nov 2017 20:56:59 -0800 Subject: crypto: salsa20 - fix blkcipher_walk API usage
From: Eric Biggers ebiggers@google.com
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
--- arch/x86/crypto/salsa20_glue.c | 7 ------- crypto/salsa20_generic.c | 7 ------- 2 files changed, 14 deletions(-)
--- a/arch/x86/crypto/salsa20_glue.c +++ b/arch/x86/crypto/salsa20_glue.c @@ -59,13 +59,6 @@ static int encrypt(struct blkcipher_desc
salsa20_ivsetup(ctx, walk.iv);
- if (likely(walk.nbytes == nbytes)) - { - salsa20_encrypt_bytes(ctx, walk.src.virt.addr, - walk.dst.virt.addr, nbytes); - return blkcipher_walk_done(desc, &walk, 0); - } - while (walk.nbytes >= 64) { salsa20_encrypt_bytes(ctx, walk.src.virt.addr, walk.dst.virt.addr, --- a/crypto/salsa20_generic.c +++ b/crypto/salsa20_generic.c @@ -188,13 +188,6 @@ static int encrypt(struct blkcipher_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,
Patches currently in stable-queue which might be from ebiggers@google.com are
queue-3.18/crypto-salsa20-fix-blkcipher_walk-api-usage.patch queue-3.18/crypto-hmac-require-that-the-underlying-hash-algorithm-is-unkeyed.patch