Hi Gustavo,

> In preparation to enabling -Wvla, remove VLA and replace it
> with dynamic memory allocation instead.
> The use of stack Variable Length Arrays needs to be avoided, as they
> can be a vector for stack exhaustion, which can be both a runtime bug
> or a security flaw. Also, in general, as code evolves it is easy to
> lose track of how big a VLA can get. Thus, we can end up having runtime
> failures that are hard to debug.
> Also, fixed as part of the directive to remove all VLAs from
> the kernel: https://lkml.org/lkml/2018/3/7/621
> Signed-off-by: Gustavo A. R. Silva <garsi...@embeddedor.com>
> ---
> Changes in v2:
> - Fix memory leak in previous patch.
> net/bluetooth/smp.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
> diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
> index a2ddae2..0fa7035 100644
> --- a/net/bluetooth/smp.c
> +++ b/net/bluetooth/smp.c
> @@ -173,7 +173,7 @@ static int aes_cmac(struct crypto_shash *tfm, const u8 
> k[16], const u8 *m,
>                   size_t len, u8 mac[16])
> {
>       uint8_t tmp[16], mac_msb[16], msg_msb[CMAC_MSG_MAX];
> -     SHASH_DESC_ON_STACK(desc, tfm);
> +     struct shash_desc *shash;

so I took this patch back out of bluetooth-next before sending the pull 
request. I think the discussion on how to fix SHASH_DESC_ON_STACK macro needs 
to complete first. Once that has concluded we can revisit if this patch is 
still needed or if another solution has been found. Same as with WiFi, these 
are not just one-shot calls where a memory allocation doesn’t matter. We need 
this for random address resolution and thus there can be many of the aes_cmac 
calls when seeing neighboring devices.



Reply via email to