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([2001:41d0:303:6f54::1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483bd6f26d7sm378556845e9.3.2026.03.01.13.07.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Mar 2026 13:07:36 -0800 (PST) From: Ruslan Valiyev To: syzbot+639ebc6ec75e96674741@syzkaller.appspotmail.com, "Daniel W . S . Almeida" , Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzkaller-bugs@googlegroups.com, Ruslan Valiyev Subject: [PATCH] media: vidtv: fix nfeeds state corruption on start_streaming failure Date: Sun, 1 Mar 2026 21:07:35 +0000 Message-ID: <20260301210735.334110-1-linuxoid@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <698aaf77.050a0220.1ad825.0033.GAE@google.com> References: <698aaf77.050a0220.1ad825.0033.GAE@google.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit syzbot reported a memory leak in vidtv_psi_service_desc_init [1]. When vidtv_start_streaming() fails inside vidtv_start_feed(), the nfeeds counter is left incremented even though no feed was actually started. This corrupts the driver state: subsequent start_feed calls see nfeeds > 1 and skip starting the mux, while stop_feed calls eventually try to stop a non-existent stream. This state corruption can also lead to memory leaks, since the mux and channel resources may be partially allocated during a failed start_streaming but never cleaned up, as the stop path finds dvb->streaming == false and returns early. Fix by decrementing nfeeds back when start_streaming fails, keeping the counter in sync with the actual number of active feeds. [1] BUG: memory leak unreferenced object 0xffff888145b50820 (size 32): comm "syz.0.17", pid 6068, jiffies 4294944486 backtrace (crc 90a0c7d4): vidtv_psi_service_desc_init+0x74/0x1b0 drivers/media/test-drivers/vidtv/vidtv_psi.c:288 vidtv_channel_s302m_init+0xb1/0x2a0 drivers/media/test-drivers/vidtv/vidtv_channel.c:83 vidtv_channels_init+0x1b/0x40 drivers/media/test-drivers/vidtv/vidtv_channel.c:524 vidtv_mux_init+0x516/0xbe0 drivers/media/test-drivers/vidtv/vidtv_mux.c:518 vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 [inline] vidtv_start_feed+0x33e/0x4d0 drivers/media/test-drivers/vidtv/vidtv_bridge.c:239 Fixes: f90cf6079bf67 ("media: vidtv: add a bridge driver") Cc: stable@vger.kernel.org Reported-by: syzbot+639ebc6ec75e96674741@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=639ebc6ec75e96674741 Signed-off-by: Ruslan Valiyev --- drivers/media/test-drivers/vidtv/vidtv_bridge.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c index b6203e10e37aa..a8a76434989c2 100644 --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c @@ -237,8 +237,10 @@ static int vidtv_start_feed(struct dvb_demux_feed *feed) if (dvb->nfeeds == 1) { ret = vidtv_start_streaming(dvb); - if (ret < 0) + if (ret < 0) { + dvb->nfeeds--; rc = ret; + } } mutex_unlock(&dvb->feed_lock); -- 2.43.0