Re: [PATCH net] netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()

From: Florian Westphal
Date: Fri Nov 03 2023 - 05:18:28 EST


Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> The problem is in nft_byteorder_eval() where we are iterating through a
> loop and writing to dst[0], dst[1], dst[2] and so on... On each
> iteration we are writing 8 bytes. But dst[] is an array of u32 so each
> element only has space for 4 bytes. That means that every iteration
> overwrites part of the previous element.
>
> I spotted this bug while reviewing commit caf3ef7468f7 ("netfilter:
> nf_tables: prevent OOB access in nft_byteorder_eval") which is a related
> issue. I think that the reason we have not detected this bug in testing
> is that most of time we only write one element.

LGTM, thanks Dan. We will route this via nf.git.