Re: [PATCH v2] cpupower/debug/i386: check mmap return value in main

[Shuah Khan <skhan@linuxfoundation.org>]

On 7/16/26 19:31, longlong yan wrote:
> The return value of mmap() is not checked. On failure mmap() returns
> MAP_FAILED, not NULL. If mmap() fails, the subsequent for-loop
> dereferences the invalid pointer (MAP_FAILED), causing a segfault.
> 
> Add a check for MAP_FAILED after mmap(), consistent with the existing
> error handling style for open() in the same function.
> 

-----
> Changes in v2:
> - Remove trailing whitespace and blank row
-----

The above changes in v2 information should be placed under
the --- after the Signed-off-by
> 
> Fixes: 7fe2f6399a84 ("cpupowerutils - cpufrequtils extended with quite some features")
> Signed-off-by: longlong yan <yanlonglong@kylinos.cn>
> ---

Here - otherwise it becomes part of the commit log and we
don't want that.

Please send v3.

>   tools/power/cpupower/debug/i386/dump_psb.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/tools/power/cpupower/debug/i386/dump_psb.c b/tools/power/cpupower/debug/i386/dump_psb.c
> index 6fb81b42ea61..fcbb73b48acb 100644
> --- a/tools/power/cpupower/debug/i386/dump_psb.c
> +++ b/tools/power/cpupower/debug/i386/dump_psb.c
> @@ -182,6 +182,11 @@ main(int argc, char *argv[])
>   	mem = mmap(mem, 0x100000 - 0xc0000, PROT_READ, MAP_SHARED, fd, 0xc0000);
>   	close(fd);
>   
> +	if (mem == MAP_FAILED) {
> +		printf("Couldn't mmap /dev/mem\n");
> +		exit(1);
> +	}
> +
>   	for (p = mem; p - mem < LEN; p+=16) {
>   		if (memcmp(p, "AMDK7PNOW!", 10) == 0) {
>   			decode_psb(p, numpst);

thanks,
-- Shuah