| Message ID | 20240223132035.3174952-1-ardb+git@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | [v2] crypto: arm64/neonbs - fix out-of-bounds access on short input | expand |
On Fri, Feb 23, 2024 at 02:20:35PM +0100, Ard Biesheuvel wrote: > From: Ard Biesheuvel <ardb@kernel.org> > > The bit-sliced implementation of AES-CTR operates on blocks of 128 > bytes, and will fall back to the plain NEON version for tail blocks or > inputs that are shorter than 128 bytes to begin with. > > It will call straight into the plain NEON asm helper, which performs all > memory accesses in granules of 16 bytes (the size of a NEON register). > For this reason, the associated plain NEON glue code will copy inputs > shorter than 16 bytes into a temporary buffer, given that this is a rare > occurrence and it is not worth the effort to work around this in the asm > code. > > The fallback from the bit-sliced NEON version fails to take this into > account, potentially resulting in out-of-bounds accesses. So clone the > same workaround, and use a temp buffer for short in/outputs. > > Fixes: fc074e130051 ("crypto: arm64/aes-neonbs-ctr - fallback to plain NEON for final chunk") > Reported-by: syzbot+f1ceaa1a09ab891e1934@syzkaller.appspotmail.com > Reviewed-by: Eric Biggers <ebiggers@google.com> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm64/crypto/aes-neonbs-glue.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) Patch applied. Thanks.
diff --git a/arch/arm64/crypto/aes-neonbs-glue.c b/arch/arm64/crypto/aes-neonbs-glue.c index bac4cabef607..467ac2f768ac 100644 --- a/arch/arm64/crypto/aes-neonbs-glue.c +++ b/arch/arm64/crypto/aes-neonbs-glue.c @@ -227,8 +227,19 @@ static int ctr_encrypt(struct skcipher_request *req) src += blocks * AES_BLOCK_SIZE; } if (nbytes && walk.nbytes == walk.total) { + u8 buf[AES_BLOCK_SIZE]; + u8 *d = dst; + + if (unlikely(nbytes < AES_BLOCK_SIZE)) + src = dst = memcpy(buf + sizeof(buf) - nbytes, + src, nbytes); + neon_aes_ctr_encrypt(dst, src, ctx->enc, ctx->key.rounds, nbytes, walk.iv); + + if (unlikely(nbytes < AES_BLOCK_SIZE)) + memcpy(d, dst, nbytes); + nbytes = 0; } kernel_neon_end();