On 5/11/2022 4:55 PM, Rasmus Villemoes wrote:
On 11/05/2022 10.53, Gaurav Jain wrote:
HW accelerated hash operations are giving incorrect hash output. so add flush and invalidate for input/output hash buffers.
Fixes: 94e3c8c4fd (crypto/fsl - Add progressive hashing support using hardware acceleration.)
AFAICT, it takes somewhat more to fix that commit; the progressive hashing is entirely broken.
It doesn't actually do anything progressive, it just stashes the address/length pairs it is given, but doesn't feed the contents of those buffers to the hardware, folding it into the hash state. So the caller
Correct.
must not touch the buffers it passes until the finalization. I.e. I think this won't work:
char buf[SOMETHING];
update_buffer(buf); hash_update(buf, len); update_buffer_again(buf); hash_update(buf, len);
Indeed, this won't work.
And this pattern can be found in e.g. drivers/dfu/dfu.c which seems to repeatedly pass the same address (dfu->i_buf_start) to ->hash_update.
At first glance, dfu asks for crc32 algorithm, so it won't use this backend. But the concept is correct: user is not forced to keep a buffer unmodified (or even allocated) after .hash_update returns.
Thanks, Horia