linux-kernel - Re: [PATCH] strparser: Fix signed/unsigned mismatch bug

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Message-ID: <20251105173434.1404676-1-nate.karstens@garmin.com>
Date: Wed, 5 Nov 2025 11:34:34 -0600
From: Nate Karstens <nate.karstens@...min.com>
To: <nate.karstens@...min.com>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <horms@...nel.org>,
        <john.fastabend@...il.com>, <kuba@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux@...blig.org>, <mrpre@....com>,
        <nate.karstens@...il.com>, <netdev@...r.kernel.org>,
        <pabeni@...hat.com>, <stable@...r.kernel.org>, <tom@...ntonium.net>
Subject: Re: [PATCH] strparser: Fix signed/unsigned mismatch bug

All right, one more time using `git send-email` (plainly I don't do this every day)...

Sabrina,

Thanks for looking at this!

I'm seeing this on kernel version 5.10.244. I know that ktls on the mainline kernel has moved away from strparser, but I think the change would be useful for anyone still using strparser (both for ktls on old kernels and other users as well). It seems that, because head->len was cast to ssize_t, it was an oversight that skb->len wasn't as well (if the intention was to use unsigned arithmetic, then there would be no need to cast head-> len).

Here is an example of the values involved with the test I'm running:

len = 16406
head->len = 1448
skb->len = 1448
stm->strp.offset = 478
(ssize_t)head->len - skb->len - stm.strp.offset = 4294966818
(ssize_t)head->len - (ssize_t)skb->len - stm.strp.offset = -478

I'm happy to update the patch, how much of this information would be useful to include in the commit message?

Nate

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