netdev - Re: [PATCH net-next 1/3] soc: fsl_qbman: use be16_to_cpu() in qm_sg_entry_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241030-enigmatic-mayfly-of-triumph-d571bb@leitao>
Date: Wed, 30 Oct 2024 03:39:58 -0700
From: Breno Leitao <leitao@...ian.org>
To: Vladimir Oltean <vladimir.oltean@....com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Madalin Bucur <madalin.bucur@....com>,
	Ioana Ciornei <ioana.ciornei@....com>,
	Radu Bulie <radu-andrei.bulie@....com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Sean Anderson <sean.anderson@...ux.dev>,
	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH net-next 1/3] soc: fsl_qbman: use be16_to_cpu() in
 qm_sg_entry_get_off()

On Tue, Oct 29, 2024 at 06:43:15PM +0200, Vladimir Oltean wrote:
> struct qm_sg_entry :: offset is a 13-bit field, declared as __be16.
> 
> When using be32_to_cpu(), a wrong value will be calculated on little
> endian systems (Arm), because type promotion from 16-bit to 32-bit,
> which is done before the byte swap and always in the CPU native
> endianness, changes the value of the scatter/gather list entry offset in
> big-endian interpretation (adds two zero bytes in the LSB interpretation).
> The result of the byte swap is ANDed with GENMASK(12, 0), so the result
> is always zero, because only those bytes added by type promotion remain
> after the application of the bit mask.
> 
> The impact of the bug is that scatter/gather frames with a non-zero
> offset into the buffer are treated by the driver as if they had a zero
> offset. This is all in theory, because in practice, qm_sg_entry_get_off()
> has a single caller, where the bug is inconsequential, because at that
> call site the buffer offset will always be zero, as will be explained in
> the subsequent change.
> 
> Flagged by sparse:
> 
> warning: cast to restricted __be32
> warning: cast from restricted __be16
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Reviewed-by: Breno Leitao <leitao@...ian.org>