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Message-ID: <4d88953a-8ffd-46a6-b1ab-16d9587b6e90@linux.intel.com>
Date: Thu, 31 Jul 2025 10:23:24 +0200
From: Dawid Osuchowski <dawid.osuchowski@...ux.intel.com>
To: Luke Howard <lukeh@...l.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net] net: dsa: validate source trunk against lags_len
On 2025-07-31 7:35 AM, Luke Howard wrote:
> A DSA frame with an invalid source trunk ID could cause an out-of-bounds read
> access of dst->lags.
>
> This patch adds a check to dsa_lag_by_id() to validate the LAG ID is not zero,
checkpatch is saying this line is not wrapped at 75 columns
> and is less than or equal to dst->lags_len. (The LAG ID is derived by adding
> one to the source trunk ID.)
>
> Note: this is in the fast path for any frames within a trunk.
>
> Signed-off-by: Luke Howard <lukeh@...l.com>
Reviewed-by: Dawid Osuchowski <dawid.osuchowski@...ux.intel.com>
Thanks,
Dawid
> ---
> include/net/dsa.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 2e148823c366c..67672c5ff22e5 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -180,6 +180,9 @@ struct dsa_switch_tree {
> static inline struct dsa_lag *dsa_lag_by_id(struct dsa_switch_tree *dst,
> unsigned int id)
> {
> + if (unlikely(id == 0 || id > dst->lags_len))
> + return NULL;
> +
> /* DSA LAG IDs are one-based, dst->lags is zero-based */
> return dst->lags[id - 1];
> }
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