Re: [PATCH 3/4] add ksm kernel shared memory driver.

[Alan Cox]

> +	r = !memcmp(old_digest, sha1_item->sha1val, SHA1_DIGEST_SIZE);
> +	mutex_unlock(&sha1_lock);
> +	if (r) {
> +		char *old_addr, *new_addr;
> +		old_addr = kmap_atomic(oldpage, KM_USER0);
> +		new_addr = kmap_atomic(newpage, KM_USER1);
> +		r = !memcmp(old_addr+PAGEHASH_LEN, new_addr+PAGEHASH_LEN,
> +			    PAGE_SIZE-PAGEHASH_LEN);

NAK - this isn't guaranteed to be robust so you could end up merging
different pages one provided by a malicious attacker.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/