[dm-devel] Crash in crypto mcryptd
Eric Biggers
ebiggers at google.com
Fri Dec 2 07:06:58 UTC 2016
On Thu, Dec 01, 2016 at 05:47:02PM -0800, Tim Chen wrote:
> On Thu, 2016-12-01 at 19:00 -0500, Mikulas Patocka wrote:
> > Hi
> >
> > There is a bug in mcryptd initialization.
> >
> > This is a test module that tries various hash algorithms. When you load
> > the module with "insmod test.ko 'alg=mcryptd(md5)'", the machine crashes.
>
> I don't think your test setup is right. The mcryptd supports only multi-buffer
> algorithm. I don't think there is such an implementation for md5.
>
> Please refer to arch/x86/crypto/sha1-mb
> multi-buffer implementation of sha1 to see the proper
> setup and usage with mcryptd. You can also run tcrypt test to
> exercise this code.
>
> Tim
No, mcryptd must not crash the kernel if it's passed the wrong algorithm.
Users can try to instantiate it with any algorithm using AF_ALG, for example:
struct sockaddr_alg addr = {
.salg_type = "hash",
.salg_name = "mcryptd(md5)",
};
int fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(fd, (struct sockaddr *)&addr, sizeof(addr));
Currently, this instantly crashes the kernel.
Eric
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