From: Andi Kleen Date: Sat, 23 Jun 2007 00:29:25 +0000 (+0200) Subject: x86_64: Ignore compat mode SYSCALL when IA32_EMULATION is not defined X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=75154f402ef18e459ff97ddece25656b6c2b329c;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git x86_64: Ignore compat mode SYSCALL when IA32_EMULATION is not defined Previously a program could switch to a compat mode segment and then execute SYSCALL and it would jump to an uninitialized MSR and crash the kernel. Instead supply a dummy target for this case. Pointed out by Jan Beulich Cc: jbeulich@novell.com Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S index fa984b53e7e..a67f87bf401 100644 --- a/arch/x86_64/kernel/entry.S +++ b/arch/x86_64/kernel/entry.S @@ -1163,3 +1163,10 @@ ENTRY(call_softirq) ret CFI_ENDPROC ENDPROC(call_softirq) + +KPROBE_ENTRY(ignore_sysret) + CFI_STARTPROC + mov $-ENOSYS,%eax + sysret + CFI_ENDPROC +ENDPROC(ignore_sysret) diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c index 64379a80d76..1200aaac403 100644 --- a/arch/x86_64/kernel/setup64.c +++ b/arch/x86_64/kernel/setup64.c @@ -150,6 +150,8 @@ void pda_init(int cpu) char boot_exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ] __attribute__((section(".bss.page_aligned"))); +extern asmlinkage void ignore_sysret(void); + /* May not be marked __init: used by software suspend */ void syscall_init(void) { @@ -160,6 +162,7 @@ void syscall_init(void) */ wrmsrl(MSR_STAR, ((u64)__USER32_CS)<<48 | ((u64)__KERNEL_CS)<<32); wrmsrl(MSR_LSTAR, system_call); + wrmsrl(MSR_CSTAR, ignore_sysret); #ifdef CONFIG_IA32_EMULATION syscall32_cpu_init ();