* [PATCH] tools intel-speed-select: Fix signed shift UB in BIT() macro
@ 2026-09-03 8:28 liujing
2026-09-10 1:06 ` srinivas pandruvada
0 siblings, 1 reply; 2+ messages in thread
From: liujing @ 2026-09-03 8:28 UTC (permalink / raw)
To: Srinivas Pandruvada; +Cc: platform-driver-x86, linux-kernel, Liu Jing
From: Liu Jing <liujing@cmss.chinamobile.com>
The BIT() macro is defined as `(1 << (x))` with a signed integer 1.
When x >= 31, this causes signed integer overflow which is undefined
behavior in C. This macro is used with BIT(31) in isst-core.c and
isst-core-mbox.c.
Fix it by using `1U` instead of `1` to perform an unsigned shift,
matching the kernel's own BIT() definition which uses unsigned.
Signed-off-by: Liu Jing <liujing@cmss.chinamobile.com>
---
--- a/tools/power/x86/intel-speed-select/isst.h
+++ b/tools/power/x86/intel-speed-select/isst.h
@@ -30,7 +30,7 @@
#include <linux/isst_if.h>
-#define BIT(x) (1 << (x))
+#define BIT(x) (1U << (x))
#define BIT_ULL(nr) (1ULL << (nr))
#define GENMASK(h, l) (((~0UL) << (l)) & (~0UL >> (sizeof(long) * 8 - 1 - (h))))
#define GENMASK_ULL(h, l) \
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] tools intel-speed-select: Fix signed shift UB in BIT() macro
2026-09-03 8:28 [PATCH] tools intel-speed-select: Fix signed shift UB in BIT() macro liujing
@ 2026-09-10 1:06 ` srinivas pandruvada
0 siblings, 0 replies; 2+ messages in thread
From: srinivas pandruvada @ 2026-09-10 1:06 UTC (permalink / raw)
To: liujing; +Cc: platform-driver-x86, linux-kernel
On Thu, 2026-09-03 at 16:28 +0800, liujing wrote:
> From: Liu Jing <liujing@cmss.chinamobile.com>
>
> The BIT() macro is defined as `(1 << (x))` with a signed integer 1.
> When x >= 31, this causes signed integer overflow which is undefined
> behavior in C. This macro is used with BIT(31) in isst-core.c and
> isst-core-mbox.c.
>
> Fix it by using `1U` instead of `1` to perform an unsigned shift,
> matching the kernel's own BIT() definition which uses unsigned.
>
> Signed-off-by: Liu Jing <liujing@cmss.chinamobile.com>
Applied to
https://git.kernel.org/pub/scm/linux/kernel/git/spandruvada/linux.git/log/?h=for-sst-v7.4.rc1
Thanks,
Srinivas
> ---
> --- a/tools/power/x86/intel-speed-select/isst.h
> +++ b/tools/power/x86/intel-speed-select/isst.h
> @@ -30,7 +30,7 @@
>
> #include <linux/isst_if.h>
>
> -#define BIT(x) (1 << (x))
> +#define BIT(x) (1U << (x))
> #define BIT_ULL(nr) (1ULL << (nr))
> #define GENMASK(h, l) (((~0UL) << (l)) & (~0UL >> (sizeof(long) * 8
> - 1 - (h))))
> #define GENMASK_ULL(h,
> l) \
>
>
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-09-03 8:28 [PATCH] tools intel-speed-select: Fix signed shift UB in BIT() macro liujing
2026-09-10 1:06 ` srinivas pandruvada
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