[PATCH AUTOSEL 6.11 100/244] tools/x86/kcpuid: Protect against faulty "max subleaf" values

Sasha Levin
2024-09-25T11:41:27Z

From: "Ahmed S. Darwish" <darwi@linutronix.de>

[ Upstream commit cf96ab1a966b87b09fdd9e8cc8357d2d00776a3a ]

Protect against the kcpuid code parsing faulty max subleaf numbers
through a min() expression. Thus, ensuring that max_subleaf will always
be ≤ MAX_SUBLEAF_NUM.

Use "u32" for the subleaf numbers since kcpuid is compiled with -Wextra,
which includes signed/unsigned comparisons warnings.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240718134755.378115-5-darwi@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/arch/x86/kcpuid/kcpuid.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/tools/arch/x86/kcpuid/kcpuid.c b/tools/arch/x86/kcpuid/kcpuid.c
index 24b7d017ec2c1..b7965dfff33a9 100644
--- a/tools/arch/x86/kcpuid/kcpuid.c
+++ b/tools/arch/x86/kcpuid/kcpuid.c
@@ -7,7 +7,8 @@
#include <string.h>
#include <getopt.h>

-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#define min(a, b) (((a) < (b)) ? (a) : (b))

typedef unsigned int u32;
typedef unsigned long long u64;
@@ -207,12 +208,9 @@ static void raw_dump_range(struct cpuid_range *range)
#define MAX_SUBLEAF_NUM 32
struct cpuid_range *setup_cpuid_range(u32 input_eax)
{
- u32 max_func, idx_func;
- int subleaf;
+ u32 max_func, idx_func, subleaf, max_subleaf;
+ u32 eax, ebx, ecx, edx, f = input_eax;
struct cpuid_range *range;
- u32 eax, ebx, ecx, edx;
- u32 f = input_eax;
- int max_subleaf;
bool allzero;

eax = input_eax;
@@ -258,7 +256,7 @@ struct cpuid_range *setup_cpuid_range(u32 input_eax)
* others have to be tried (0xf)
*/
if (f == 0x7 || f == 0x14 || f == 0x17 || f == 0x18)
- max_subleaf = (eax & 0xff) + 1;
+ max_subleaf = min((eax & 0xff) + 1, max_subleaf);

if (f == 0xb)
max_subleaf = 2;
--
2.43.0