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[kvm-unit-tests,v2,13/16] x86/emulator64: Add non-null selector test

Message ID 20230413184219.36404-14-minipli@grsecurity.net (mailing list archive)
State New, archived
Headers show
Series x86: cleanups, fixes and new tests | expand

Commit Message

Mathias Krause April 13, 2023, 6:42 p.m. UTC 
Complement the NULL selector based RPL!=CPL test with a non-NULL one to
ensure the failing segment selector is correctly reported through the
exception error code.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
---
 x86/emulator64.c | 7 +++++++
 1 file changed, 7 insertions(+)
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Patch

diff --git a/x86/emulator64.c b/x86/emulator64.c
index a98c66c2b44f..492e8a292839 100644
--- a/x86/emulator64.c
+++ b/x86/emulator64.c
@@ -401,6 +401,13 @@  static void test_sreg(volatile uint16_t *mem)
 	       exception_error_code() == 0 && read_ss() == 0,
 	       "mov null, %%ss (with ss.rpl != cpl)");
 
+	// check for exception when ss.rpl != cpl on non-null segment load
+	*mem = KERNEL_DS | 3;
+	asm volatile(ASM_TRY("1f") "mov %0, %%ss; 1:" : : "m"(*mem));
+	report(exception_vector() == GP_VECTOR &&
+	       exception_error_code() == KERNEL_DS && read_ss() == 0,
+	       "mov non-null, %%ss (with ss.rpl != cpl)");
+
 	write_ss(ss);
 }