From 03889ae76dea9c5e63e64df495fd77d613a03a80 Mon Sep 17 00:00:00 2001
From: "Timothy B. Terriberry" <tterribe@xiph.org>
Date: Tue, 28 Jun 2022 22:33:43 -0700
Subject: [PATCH] Check the return value of __get_cpuid().
This function can fail if CPUID is not supported or the maximum
supported value of EAX is less than the requested one.
Check the return value and explicitly disable all SIMD if it does
fail.
This was happening before implicitly because of the initialization
of info[] to zero, but being explicit about it makes it less likely
someone will break this behavior because they did not realize what
was going on.
---
celt/x86/x86cpu.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/celt/x86/x86cpu.c b/celt/x86/x86cpu.c
index 080eb25e4..accf0676b 100644
--- a/celt/x86/x86cpu.c
+++ b/celt/x86/x86cpu.c
@@ -81,7 +81,12 @@ static void cpuid(unsigned int CPUInfo[4], unsigned int InfoType)
);
#endif
#elif defined(CPU_INFO_BY_C)
- __get_cpuid(InfoType, &(CPUInfo[0]), &(CPUInfo[1]), &(CPUInfo[2]), &(CPUInfo[3]));
+ if !(__get_cpuid(InfoType, &(CPUInfo[0]), &(CPUInfo[1]), &(CPUInfo[2]), &(CPUInfo[3]))) {
+ /* Our function cannot fail, but __get_cpuid can.
+ Returning all zeroes will effectively disable all SIMD, which is
+ what we want on CPUs that don't support CPUID. */
+ CPUInfo[3] = CPUInfo[2] = CPUInfo[1] = CPUInfo[0] = 0;
+ }
#endif
}
@@ -98,7 +103,7 @@ typedef struct CPU_Feature{
static void opus_cpu_feature_check(CPU_Feature *cpu_feature)
{
- unsigned int info[4] = {0};
+ unsigned int info[4];
unsigned int nIds = 0;
cpuid(info, 0);
--
GitLab