In the Linux kernel, the following vulnerability has been resolved:
media: vidtv: fix nfeeds state corruption on start_streaming failure
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