If gcm_mode_encrypt_contiguous_blocks() is called more than once
in succession, with the accumulated lengths being less than
blocksize, ctx->copy_to will be incorrectly advanced. Later, if
out is NULL, the bcopy at line 114 will overflow
ctx->gcm_copy_to since ctx->gcm_remainder_len is larger than the
ctx->gcm_copy_to buffer can hold.
The fix is to set ctx->copy_to only if it's not already set.
For ZoL the issue may be academic, since in all my testing I wasn't
able to hit neither of both conditions needed to trigger it, but
other consumers can easily do so.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes#9660
3ac34ca375