crypto: salsa20 - don't access already-freed walk.iv
authorEric Biggers <ebiggers@google.com>
Wed, 10 Apr 2019 06:46:30 +0000 (23:46 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 22 May 2019 05:37:36 +0000 (07:37 +0200)
commit3b5ddd5ea0165fc6b11e1e200a14797adb51b4cb
tree39b7cf05a4cb197d3e3a09d7eafcb3ccd0c9de37
parent7a32ad34b889f874be154ec93aff892c975d2731
crypto: salsa20 - don't access already-freed walk.iv

commit edaf28e996af69222b2cb40455dbb5459c2b875a upstream.

If the user-provided IV needs to be aligned to the algorithm's
alignmask, then skcipher_walk_virt() copies the IV into a new aligned
buffer walk.iv.  But skcipher_walk_virt() can fail afterwards, and then
if the caller unconditionally accesses walk.iv, it's a use-after-free.

salsa20-generic doesn't set an alignmask, so currently it isn't affected
by this despite unconditionally accessing walk.iv.  However this is more
subtle than desired, and it was actually broken prior to the alignmask
being removed by commit b62b3db76f73 ("crypto: salsa20-generic - cleanup
and convert to skcipher API").

Since salsa20-generic does not update the IV and does not need any IV
alignment, update it to use req->iv instead of walk.iv.

Fixes: 2407d60872dd ("[CRYPTO] salsa20: Salsa20 stream cipher")
Cc: stable@vger.kernel.org
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/salsa20_generic.c