In user-mode emulation, QEMU uses the default setting of the LDT base and limit, which places it at the bottom 64K of virtual address space. However, by default there is no LDT at all in Linux processes, and therefore the limit should be 0.
This is visible as a NULL pointer dereference in LSL and LAR instructions when they try to read the LDT at an unmapped address. Resolves: #1376 Cc: [email protected] Signed-off-by: Paolo Bonzini <[email protected]> --- target/i386/cpu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 4f99cbc5c0b..455caff6b23 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -8649,7 +8649,11 @@ static void x86_cpu_reset_hold(Object *obj, ResetType type) env->idt.limit = 0xffff; env->gdt.limit = 0xffff; +#if defined(CONFIG_USER_ONLY) + env->ldt.limit = 0; +#else env->ldt.limit = 0xffff; +#endif env->ldt.flags = DESC_P_MASK | (2 << DESC_TYPE_SHIFT); env->tr.limit = 0xffff; env->tr.flags = DESC_P_MASK | (11 << DESC_TYPE_SHIFT); -- 2.51.0
