| Message ID | 20171129045659.16372-1-ebiggers3@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
On Tue, Nov 28, 2017 at 08:56:59PM -0800, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > 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> Patch applied. Thanks.
diff --git a/arch/x86/crypto/salsa20_glue.c b/arch/x86/crypto/salsa20_glue.c index 399a29d067d6..cb91a64a99e7 100644 --- a/arch/x86/crypto/salsa20_glue.c +++ b/arch/x86/crypto/salsa20_glue.c @@ -59,13 +59,6 @@ static int encrypt(struct blkcipher_desc *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, 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,