Re: [PATCH] crypto: authenc - Fix sleep in atomic context in decrypt_tail

Corentin Labbe
2022-01-27T13:39:03Z

Le Wed, Jan 19, 2022 at 05:58:40PM +1100, Herbert Xu a écrit :
> On Tue, Jan 18, 2022 at 08:52:53AM +0100, Corentin Labbe wrote:
> >
> > With my patch, I got:
> > [ 38.515668] BUG: sleeping function called from invalid context at crypto/skcipher.c:482
> > [ 38.523708] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 84, name: 1c15000.crypto-
> > [ 38.532176] preempt_count: 200, expected: 0
> > [ 38.536381] CPU: 6 PID: 84 Comm: 1c15000.crypto- Not tainted 5.16.0-next-20220115-00124-g13473e8fac33-dirty #116
> > [ 38.546551] Hardware name: Allwinner A83t board
> > [ 38.551100] unwind_backtrace from show_stack+0x10/0x14
> > [ 38.556358] show_stack from dump_stack_lvl+0x40/0x4c
> > [ 38.561428] dump_stack_lvl from __might_resched+0x118/0x154
> > [ 38.567107] __might_resched from skcipher_walk_virt+0xe8/0xec
> > [ 38.572955] skcipher_walk_virt from crypto_cbc_decrypt+0x2c/0x170
> > [ 38.579147] crypto_cbc_decrypt from crypto_skcipher_decrypt+0x38/0x5c
> > [ 38.585680] crypto_skcipher_decrypt from authenc_verify_ahash_done+0x18/0x34
> > [ 38.592825] authenc_verify_ahash_done from crypto_finalize_request+0x6c/0xe4
> > [ 38.599974] crypto_finalize_request from sun8i_ss_hash_run+0x73c/0xb98
> > [ 38.606602] sun8i_ss_hash_run from crypto_pump_work+0x1a8/0x330
> > [ 38.612616] crypto_pump_work from kthread_worker_fn+0xa8/0x1c4
> > [ 38.618550] kthread_worker_fn from kthread+0xf0/0x110
> > [ 38.623701] kthread from ret_from_fork+0x14/0x2c
> > [ 38.628414] Exception stack(0xc2247fb0 to 0xc2247ff8)
> > [ 38.633468] 7fa0: 00000000 00000000 00000000 00000000
> > [ 38.641640] 7fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > [ 38.649809] 7fe0:i 00000000 00000000 00000000 00000000 00000013 00000000
> >
> > This is when testing hmac(sha1) on my crypto driver sun8i-ss and crypto testing authenc(hmac-sha1-sun8i-ss,cbc(aes-generic)).
> >
> > Do you have any idea to better fix my issue ?
>
> This backtrace is caused by a bug in authenc:
>
> ---8<---
> The function crypto_authenc_decrypt_tail discards its flags
> argument and always relies on the flags from the original request
> when starting its sub-request.
>
> This is clearly wrong as it may cause the SLEEPABLE flag to be
> set when it shouldn't.
>
> Fixes: 92d95ba91772 ("crypto: authenc - Convert to new AEAD interface")
> Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
>
> diff --git a/crypto/authenc.c b/crypto/authenc.c
> index 670bf1a01d00..17f674a7cdff 100644
> --- a/crypto/authenc.c
> +++ b/crypto/authenc.c
> @@ -253,7 +253,7 @@ static int crypto_authenc_decrypt_tail(struct aead_request *req,
> dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
>
> skcipher_request_set_tfm(skreq, ctx->enc);
> - skcipher_request_set_callback(skreq, aead_request_flags(req),
> + skcipher_request_set_callback(skreq, flags,
> req->base.complete, req->base.data);
> skcipher_request_set_crypt(skreq, src, dst,
> req->cryptlen - authsize, req->iv);
> --

This fixes my issue.

Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>

Thanks