linux-kernel - Re: [PATCH bpf-next v4 04/15] selftests/bpf: test_xsk: fix memory leak in testapp_stats_rx

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] [day] [month] [year] [list]

Message-ID: <fd600cd5-062e-4806-9e8e-b7f6aacad242@bootlin.com>
Date: Fri, 26 Sep 2025 08:39:28 +0200
From: Bastien Curutchet <bastien.curutchet@...tlin.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc: Björn Töpel <bjorn@...nel.org>,
 Magnus Karlsson <magnus.karlsson@...el.com>,
 Jonathan Lemon <jonathan.lemon@...il.com>,
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>,
 Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau
 <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>,
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>,
 Shuah Khan <shuah@...nel.org>, "David S. Miller" <davem@...emloft.net>,
 Jakub Kicinski <kuba@...nel.org>, Jesper Dangaard Brouer <hawk@...nel.org>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
 Alexis Lothore <alexis.lothore@...tlin.com>, netdev@...r.kernel.org,
 bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v4 04/15] selftests/bpf: test_xsk: fix memory
 leak in testapp_stats_rx_dropped()

Hi Maciej,

On 9/25/25 3:32 PM, Maciej Fijalkowski wrote:
> On Wed, Sep 24, 2025 at 04:49:39PM +0200, Bastien Curutchet (eBPF Foundation) wrote:
>> testapp_stats_rx_dropped() generates pkt_stream twice. The last
>> generated is released by pkt_stream_restore_default() at the end of the
>> test but we lose the pointer of the first pkt_stream.
>>
>> Release the 'middle' pkt_stream when it's getting replaced to prevent
>> memory leaks.
>>
>> Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@...tlin.com>
>> ---
>>   tools/testing/selftests/bpf/test_xsk.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/tools/testing/selftests/bpf/test_xsk.c b/tools/testing/selftests/bpf/test_xsk.c
>> index 8d7c38eb32ca3537cb019f120c3350ebd9f8c6bc..eb18288ea1e4aa1c9337d16333b7174ecaed0999 100644
>> --- a/tools/testing/selftests/bpf/test_xsk.c
>> +++ b/tools/testing/selftests/bpf/test_xsk.c
>> @@ -536,6 +536,13 @@ static void pkt_stream_receive_half(struct test_spec *test)
>>   	struct pkt_stream *pkt_stream = test->ifobj_tx->xsk->pkt_stream;
>>   	u32 i;
>>   
>> +	if (test->ifobj_rx->xsk->pkt_stream != test->rx_pkt_stream_default)
>> +		/* Packet stream has already been replaced so we have to release this one.
>> +		 * The newly created one will be freed by the restore_default() at the
>> +		 * end of the test
>> +		 */
>> +		pkt_stream_delete(test->ifobj_rx->xsk->pkt_stream);
> 
> I don't see why this one is not addressed within test case
> (testapp_stats_rx_dropped()) and other fix is (testapp_xdp_shared_umem()).
> 

pkt_stream_receive_half() can be used by other tests. I thought it would 
be more convenient for people writing testapp_*() functions if they 
didn't have to worry about releasing these kind of pointer themselves.

The same approach can't be used in testapp_xdp_shared_umem(), because we 
need to wait for the test to complete before releasing the pointers.

-- 
Bastien Curutchet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com