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RTC: Fix null pointer crash in RTC2RTMP when start packet is missing. v6.0.175 v7.0.63 (#4451)

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Try to fix #4450

The SRS transcode rtp packets, whose sequence number in range [start,
end], to one rtmp packet, but when the first rtp packet is empty, then
this crash happens.

check #4450 for details.

5.0release and 6.0release branch.
develop branch already has its own solution.

So this PR is targeting to **6.0release**.

find the first not empty rtp packet in seq range [start, end].

---------

Co-authored-by: OSSRS-AI <winlinam@gmail.com>
Co-authored-by: winlin <winlinvip@gmail.com>
This commit is contained in:
Jacob Su 2025-08-27 06:42:50 +08:00 committed by winlin
parent 72ddc28d97
commit eaa3d512ee
4 changed files with 121 additions and 2 deletions
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2
trunk/doc/CHANGELOG.md
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@ -7,6 +7,7 @@ The changelog for SRS.
<a name="v7-changes"></a>
## SRS 7.0 Changelog
* v7.0, 2025-08-26, Merge [#4451](https://github.com/ossrs/srs/pull/4451): RTC: Fix null pointer crash in RTC2RTMP when start packet is missing. v7.0.63 (#4451)
* v7.0, 2025-08-25, Merge [#4452](https://github.com/ossrs/srs/pull/4452): AI: Implement stream publish token system to prevent race conditions across all protocols. v7.0.62 (#4452)
* v7.0, 2025-08-22, Merge [#4449](https://github.com/ossrs/srs/pull/4449): Refine source lock. v7.0.61 (#4449)
* v7.0, 2025-08-21, Merge [#4447](https://github.com/ossrs/srs/pull/4447): AI: Always enable WebRTC and enforce C++98 compatibility. v7.0.60 (#4447)
@ -76,6 +77,7 @@ The changelog for SRS.
<a name="v6-changes"></a>
## SRS 6.0 Changelog
* v6.0, 2025-08-26, Merge [#4451](https://github.com/ossrs/srs/pull/4451): RTC: Fix null pointer crash in RTC2RTMP when start packet is missing. v6.0.175 (#4451)
* v6.0, 2025-08-16, Merge [#4441](https://github.com/ossrs/srs/pull/4441): fix err memory leak in rtc to rtmp bridge. v6.0.174 (#4441)
* v6.0, 2025-08-14, Merge [#4161](https://github.com/ossrs/srs/pull/4161): fix hls & dash segments cleanup. v6.0.173 (#4161)
* v6.0, 2025-08-12, Merge [#4230](https://github.com/ossrs/srs/pull/4230): MP4 DVR: Fix audio/video synchronization issues in WebRTC recordings. v6.0.172 (#4230)

2
trunk/src/core/srs_core_version6.hpp
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@ -9,6 +9,6 @@
#define VERSION_MAJOR 6
#define VERSION_MINOR 0
#define VERSION_REVISION 174
#define VERSION_REVISION 175
#endif

2
trunk/src/core/srs_core_version7.hpp
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@ -9,6 +9,6 @@
#define VERSION_MAJOR 7
#define VERSION_MINOR 0
#define VERSION_REVISION 62
#define VERSION_REVISION 63
#endif

117
trunk/src/utest/srs_utest_rtc2.cpp
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@ -1514,3 +1514,120 @@ VOID TEST(KernelRTC2Test, SrsRtcFrameBuilderVideoFrameDetectorNullPacketHandling
EXPECT_FALSE(frame_ready); // Should not be ready without packets
}
}
// Mock bridge for testing SrsRtcFrameBuilder
class MockStreamBridge : public ISrsStreamBridge
{
public:
srs_error_t last_error;
int frame_count;
MockStreamBridge()
{
last_error = srs_success;
frame_count = 0;
}
virtual ~MockStreamBridge()
{
srs_freep(last_error);
}
virtual srs_error_t initialize(ISrsRequest *r)
{
return srs_success;
}
virtual srs_error_t on_publish()
{
return srs_success;
}
virtual srs_error_t on_frame(SrsSharedPtrMessage *frame)
{
frame_count++;
return srs_success;
}
virtual void on_unpublish()
{
}
};
VOID TEST(KernelRTC2Test, SrsRtcFrameBuilderPacketVideoRtmpNullPointerCrash)
{
srs_error_t err;
// Test reproducing the null pointer crash from issue #4450 fixed by PR #4451
//
// ISSUE BACKGROUND:
// Before PR 4451, the packet_video_rtmp() function assumed that the packet at the
// 'start' sequence number would always be available in the cache. However, due to
// network packet loss or reordering, the packet at the start position could be missing.
//
// THE CRASH:
// The original code did: pkt = cache_video_pkts_[cache_index(start)].pkt;
// When pkt was NULL, calling pkt->get_avsync_time() caused a segmentation fault.
//
// THE FIX:
// PR #4451 added a loop to find the first non-null packet in the sequence range
// instead of blindly using the packet at the start position.
//
// This test simulates the crash scenario: packets exist at positions 101, 102, 103
// but the start packet (100) is missing. With the fix, the function should use
// packet 101 (first available) instead of crashing on the missing packet 100.
if (true) {
MockStreamBridge bridge;
SrsRtcFrameBuilder frame_builder(&bridge);
// Skip initialization and directly set up the test scenario
// We only need to test the packet_video_rtmp function, not the full initialization
// Manually populate the video cache to simulate the crash scenario
// We'll store packets at positions 101, 102, 103 but NOT at position 100 (start)
// This simulates network packet loss where the first packet is missing
// Create test packets with payload to ensure nb_payload > 0
SrsRtpPacket *pkt101 = mock_create_test_rtp_packet(101, 1000, false);
SrsRtpPacket *pkt102 = mock_create_test_rtp_packet(102, 1000, false);
SrsRtpPacket *pkt103 = mock_create_test_rtp_packet(103, 1000, true); // marker bit
// Add some payload to ensure packets are not empty
char payload_data[] = "test_payload_data";
SrsRtpRawPayload *payload101 = new SrsRtpRawPayload();
payload101->payload = (char *)payload_data;
payload101->nn_payload = strlen(payload_data);
pkt101->set_payload(payload101, SrsRtpPacketPayloadTypeRaw);
SrsRtpRawPayload *payload102 = new SrsRtpRawPayload();
payload102->payload = (char *)payload_data;
payload102->nn_payload = strlen(payload_data);
pkt102->set_payload(payload102, SrsRtpPacketPayloadTypeRaw);
SrsRtpRawPayload *payload103 = new SrsRtpRawPayload();
payload103->payload = (char *)payload_data;
payload103->nn_payload = strlen(payload_data);
pkt103->set_payload(payload103, SrsRtpPacketPayloadTypeRaw);
// Set the avsync time for the packets to avoid other null pointer issues
pkt101->set_avsync_time(1000);
pkt102->set_avsync_time(1000);
pkt103->set_avsync_time(1000);
// Store packets in cache (but skip sequence 100 - this is the missing start packet)
frame_builder.video_cache_->store_packet(pkt101);
frame_builder.video_cache_->store_packet(pkt102);
frame_builder.video_cache_->store_packet(pkt103);
// Before the fix in PR #4451, calling packet_video_rtmp(100, 103) would crash
// because it would try to access cache_video_pkts_[cache_index(100)].pkt which is NULL
// and then call pkt->get_avsync_time() causing a null pointer dereference
// The fix ensures we find the first non-null packet (101) instead of assuming
// the start packet (100) exists
HELPER_EXPECT_SUCCESS(frame_builder.packet_video_rtmp(100, 103));
// Verify that a frame was successfully processed
EXPECT_EQ(1, bridge.frame_count);
}
}