Hi Herbert,
On Tue, Nov 26, 2019 at 03:58:45PM +0800, Herbert Xu wrote:
> On Tue, Nov 26, 2019 at 12:32:38AM -0500, Daniel Jordan wrote:
> >
> > I think it's possible for a task in padata_do_parallel() racing with another in
> > padata_replace() to use a pd after free. The synchronize_rcu() comes after the
> > pd_old->refcnt's are dec'd.
>
> Thanks. I've fixed this as well as the CPU mask issue you identified
> earlier.
>
> ---8<---
> If the pcrypt template is used multiple times in an algorithm, then a
> deadlock occurs because all pcrypt instances share the same
> padata_instance, which completes requests in the order submitted. That
> is, the inner pcrypt request waits for the outer pcrypt request while
> the outer request is already waiting for the inner.
>
> This patch fixes this by allocating a set of queues for each pcrypt
> instance instead of using two global queues. In order to maintain
> the existing user-space interface, the pinst structure remains global
> so any sysfs modifications will apply to every pcrypt instance.
>
> Note that when an update occurs we have to allocate memory for
> every pcrypt instance. Should one of the allocations fail we
> will abort the update without rolling back changes already made.
>
> The new per-instance data structure is called padata_shell and is
> essentially a wrapper around parallel_data.
>
> Reproducer:
>
> #include <linux/if_alg.h>
> #include <sys/socket.h>
> #include <unistd.h>
>
> int main()
> {
> struct sockaddr_alg addr = {
> .salg_type = "aead",
> .salg_name = "pcrypt(pcrypt(rfc4106-gcm-aesni))"
> };
> int algfd, reqfd;
> char buf[32] = { 0 };
>
> algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
> bind(algfd, (void *)&addr, sizeof(addr));
> setsockopt(algfd, SOL_ALG, ALG_SET_KEY, buf, 20);
> reqfd = accept(algfd, 0, 0);
> write(reqfd, buf, 32);
> read(reqfd, buf, 16);
> }
>
> Reported-by: syzbot+56c7151cad94eec37c521f0e47d2eee53f9361c4@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 5068c7a883d1 ("crypto: pcrypt - Add pcrypt crypto parallelization wrapper")
> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
I tried applying the following patches and running syzkaller again:
padata: Remove unused padata_remove_cpu
padata: Remove broken queue flushing
crypto: pcrypt - Fix user-after-free on module unload
[v3] crypto: pcrypt - Avoid deadlock by using per-instance padata queues
This time I got a crypto self-test failure when
"pcrypt(pcrypt(rfc4106-gcm-aesni))" was instantiated:
[ 2220.165113] alg: aead: pcrypt(pcrypt(rfc4106-gcm-aesni)) encryption corrupted request struct on test vector 0, cfg="uneven misaligned splits, may sleep"
[ 2220.170295] alg: aead: changed 'req->base.flags'
[ 2220.171799] Kernel panic - not syncing: alg: self-tests for pcrypt(pcrypt(rfc4106-gcm-aesni)) (rfc4106(gcm(aes))) failed in panic_on_fail mode!
So the algorithm is not preserving aead_request::base.flags.
- Eric
