[ntoskrnl7]

Summary

Fix LdkCurrentTeb() so the stack-low-limit TEB cache is only accepted when it belongs to the current statically linked LDK instance and the current ETHREAD.

This matters when more than one LDK-linked driver is loaded. The kernel stack cache slot is shared by the executing thread, so one driver instance can observe a TEB pointer left by another instance unless the cached TEB is validated against this instance's PEB.

Changes

• Validate cached TEB ProcessEnvironmentBlock against LdkCurrentPeb().
• Keep the existing current-thread validation.
• Add TebForeignStackCacheTest to simulate a foreign cached TEB in the stack slot.
• Add a two-driver integration test:
  • LdkMultiA.sys
  • LdkMultiB.sys
  • LdkMultiProbe.exe
• The probe opens both drivers from one user-mode thread and verifies that A/B keep distinct TEB/PEB/TLS/LastError state while running on the same ETHREAD.

Validation

• cmake -S test -B artifacts\build\teb-instance-pr-x64 -A x64 -DCMAKE_BUILD_TYPE=Debug
• cmake --build artifacts\build\teb-instance-pr-x64 --config Debug -- /m
• cmake --build artifacts\build\teb-instance-pr-x64 --config Release -- /m
• VM Debug multi-instance load/probe/unload: PASS
• VM Release multi-instance load/probe/unload: PASS

Representative VM output:

[LdkMultiProbe] PASS A_TEB=... B_TEB=... A_PEB=... B_PEB=... Thread=...
PROBE_RC=0
STOP_B_RC=0
STOP_A_RC=0
DELETE_B_RC=0
DELETE_A_RC=0
PASS