[2511] NetworkPkg: Ip4Dxe/Ip6Dxe: Set SB notify to NULL after event close

[makubacki]

Description

Ip4StartAutoConfig() and Ip6ConfigStartStatefulAutoConfig() close the DHCP service binding notify event when the service child is successfully created, but do not NULL the instance field afterward.

On re-entry, the stale handle passes the non-NULL condition and is closed a second time, which results in a page fault with memory protections enabled.

This change sets the event field to NULL immediately after CloseEvent() so that subsequent calls skip attempting to close the event again.

Code design issue in original implementation. Not a regression.

• Impacts functionality?
• Impacts security?
• Breaking change?
• Includes tests?
• Includes documentation?

How This Was Tested

PXE boot with a specific Kensington USB HUB and memory protections enabled.

Repro snippets from debug log:

[CoreCreateEventInternal]: EVENT CREATED. D6A2CB7F-6A18-4E2F-B43B-9920A733700A
...
[Ip4StartAutoConfig]: EVENT CLOSED. 9FB1A1F3-3B71-4324-B39A-745CBB015FFF
[CoreCloseEvent]: EVENT CLOSED. D6A2CB7F-6A18-4E2F-B43B-9920A733700A
...
[Ip4StartAutoConfig]: EVENT CLOSED. 9FB1A1F3-3B71-4324-B39A-745CBB015FFF
[CoreCloseEvent]: EVENT CLOSED. D6A2CB7F-6A18-4E2F-B43B-9920A733700A

Integration Instructions

N/A

[apop5]

Its good that you are finding and fixing these.

How are the interfaces being exercised? Was it a shell test app or something else that is verifying everything? Asking because something that could exercise all the network interfaces would be useful for testing.

[makubacki]

Its good that you are finding and fixing these.

How are the interfaces being exercised? Was it a shell test app or something else that is verifying everything? Asking because something that could exercise all the network interfaces would be useful for testing.

Unfortunately, it is through manual testing of different scenarios on different hardware. Given the emerging trend of these issues in NetworkPkg, some automated testing likely would find more.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (release/202511@a460671). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
NetworkPkg/Ip4Dxe/Ip4Config2Impl.c	0.00%	1 Missing ⚠️
NetworkPkg/Ip6Dxe/Ip6ConfigImpl.c	0.00%	1 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##             release/202511   #1662   +/-   ##
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  Coverage                  ?   0.55%           
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  Files                     ?     165           
  Lines                     ?   72366           
  Branches                  ?    1789           
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  Hits                      ?     402           
  Misses                    ?   71957           
  Partials                  ?       7           

Flag	Coverage Δ
NetworkPkg	0.55% <0.00%> (?)

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