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Mon, 2 Nov 2026 14:17:20 +0000 (UTC) Received: from [100.91.101.41] (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 531F6433 for ; Mon, 2 Nov 2026 14:17:20 +0000 (UTC) Message-ID: <094a9e87-a6ff-4be3-a9ff-014c033345e5@redhat.com> Date: Mon, 2 Nov 2026 15:17:19 +0100 X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v2 2/2] devlink: sb: do not dereference a missing shared buffer To: netdev@vger.kernel.org References: <20261102131505.611343-1-xiaolinkui@126.com> <20261102131505.611343-3-xiaolinkui@126.com> Content-Language: en-US From: Ivan Vecera In-Reply-To: <20261102131505.611343-3-xiaolinkui@126.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 On 11/2/26 14:15, Linkui Xiao wrote: > From: Linkui Xiao > > devl_sb_unregister() looks the shared buffer up by index and only warns > when it is not on the list. list_del() and kfree() are then called on the > NULL result, so unregistering an index that was never registered, or > unregistering the same index twice, turns the warning into a NULL pointer > dereference. list is the first member of struct devlink_sb, so list_del() > reads the next and prev pointers from address 0 before storing to them. > > The register side already fails gracefully: devl_sb_register() returns > -EEXIST when the index is taken. Make the unregister side symmetric and > return after the warning. > > Fixes: bf7974710a40 ("devlink: add shared buffer configuration") > Signed-off-by: Linkui Xiao > Reviewed-by: Simon Horman > Link: https://lore.kernel.org/r/20261030033332.3685172-3-xiaolinkui@126.com > --- > v2: reposted against net-next at Simon's suggestion; no code change. Reviewed-by: Ivan Vecera