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Cisco Bug: CSCun71762 - 100-Continue handshake causes KDB

Last Modified

Jun 21, 2020

Products (4)

  • Cisco Videoscape Distribution Suite for Television
  • Cisco TV Streamer Application
  • Cisco Visual Quality Experience (VQE) Channel Provisioning Tools
  • Cisco Visual Quality Experience Application

Known Affected Releases

1.0(0) 3.4(2)

Description (partial)

Recorder crashes when archiving recorded content, and either reboots with a core file generated, or traps into kernel debugger.

The recorder uses an HTTP PUT verb to initiate sending data to an archive.  The HTTP PUT semantics allows for the client (recorder) to send an "Expect: 100-Continue" header as part of the initial HTTP PUT send by the recorder to server (archive).  When using the 100-Continue handshake, the recorder will then wait to start sending the data for the PUT until the archive sends back a 100-Continue message.  This 100-Continue handshake gives the archive an opportunity to reject the PUT request before the client starts blasting data.

Without using the 100-Continue handshake, the recorder will just start blasting data to the archive immediately after sending the initial HTTP PUT.  The 100-Continue handshake is new code in the 3.4.2 branch.  This new code has a window of opportunity where if the 100-Continue response from the archive shows up is close proximity of time to a 10 second timeout after having sent the PUT request, the recorder can attempt to dereference a NULL pointer.
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