On Thu, Oct 21, 2021 at 02:30:28PM -0400, Daniel Jordan wrote:
> These three events can race when pcrypt is used multiple times in a
> template ("pcrypt(pcrypt(...))"):
>
> 1. [taskA] The caller makes the crypto request via crypto_aead_encrypt()
> 2. [kworkerB] padata serializes the inner pcrypt request
> 3. [kworkerC] padata serializes the outer pcrypt request
>
> 3 might finish before the call to crypto_aead_encrypt() returns in 1,
> resulting in two possible issues.
>
> First, a use-after-free of the crypto request's memory when, for
> example, taskA writes to the outer pcrypt request's padata->info in
> pcrypt_aead_enc() after kworkerC completes the request.
>
> Second, the outer pcrypt request overwrites the inner pcrypt request's
> return code with -EINPROGRESS, making a successful request appear to
> fail. For instance, kworkerB writes the outer pcrypt request's
> padata->info in pcrypt_aead_done() and then taskA overwrites it
> in pcrypt_aead_enc().
>
> Avoid both situations by delaying the write of padata->info until after
> the inner crypto request's return code is checked. This prevents the
> use-after-free by not touching the crypto request's memory after the
> next-inner crypto request is made, and stops padata->info from being
> overwritten.
>
> Fixes: 5068c7a883d16 ("crypto: pcrypt - Add pcrypt crypto parallelization wrapper")
> Reported-by: syzbot+b187b77c8474f9648fae@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
> ---
>
> So, pcrypt(pcrypt(...)) doesn't make all that much sense, but apparently
> there's not an easy way to prevent it [1], so I'm going with the minimal
> fix.
>
> [1] https://lkml.kernel.org/20171230083744.vuclnbs677tj7pi2@xxxxxxxxxxxxxxxxx/
>
> crypto/pcrypt.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
Patch applied. Thanks.
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
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