Messages in this thread | | | Date | Wed, 3 Jul 2019 22:21:08 +0200 | From | Michal Suchánek <> | Subject | Re: [PATCH] crypto: user - prevent operating on larval algorithms |
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On Wed, 3 Jul 2019 22:30:57 +0800 Herbert Xu <herbert@gondor.apana.org.au> wrote:
> On Tue, Jul 02, 2019 at 02:17:00PM -0700, Eric Biggers wrote: > > From: Eric Biggers <ebiggers@google.com> > > > > Michal Suchanek reported [1] that running the pcrypt_aead01 test from > > LTP [2] in a loop and holding Ctrl-C causes a NULL dereference of > > alg->cra_users.next in crypto_remove_spawns(), via crypto_del_alg(). > > The test repeatedly uses CRYPTO_MSG_NEWALG and CRYPTO_MSG_DELALG. > > > > The crash occurs when the instance that CRYPTO_MSG_DELALG is trying to > > unregister isn't a real registered algorithm, but rather is a "test > > larval", which is a special "algorithm" added to the algorithms list > > while the real algorithm is still being tested. Larvals don't have > > initialized cra_users, so that causes the crash. Normally pcrypt_aead01 > > doesn't trigger this because CRYPTO_MSG_NEWALG waits for the algorithm > > to be tested; however, CRYPTO_MSG_NEWALG returns early when interrupted. > >
Do you have some way to reproduce this reliably?
I suppose you would have to send a signal to the process for the call to get interrupted, right?
Thanks
Michal
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