Re: [PATCH v11 37/38] dyndbg: add +c flag to count pr_debug calls without printing

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] lib: Kernel oops when modifying string literal in ddebug_exec_queries
--

commit 33851d8d7a58ba9b9a4cd975835feabf66d636db
Author: Jim Cromie <jim.cromie@gmail.com>

dyndbg: add +c flag to count pr_debug calls without printing

This commit introduces a new "+c" flag for dynamic debug to count pr_debug
calls without actually printing them, saving memory bandwidth. It adds a
per-CPU counter for the hits and a "reset_stats" control command to clear
the counters.

> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index 88440c1f6abba..9b789287afe56 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c

[ ... ]

> @@ -727,6 +745,11 @@ static int ddebug_exec_queries(char *query, const char *modname)
>  		if (!query || !*query || *query == '#')
>  			continue;
>  
> +		if (!strcmp(strstrip(query), "reset_stats")) {

[Severity: High]
Will this cause a kernel oops when parsing module parameters?

If a user supplies the dyndbg or module.dyndbg parameter without an
explicit value, ddebug_dyndbg_param_cb() handles it by falling back to
a string literal:

    ddebug_exec_queries((val ? val : "+p"), modname);

Since strstrip() modifies the string in-place by writing a null byte at
the end of the processed string, passing the read-only literal "+p" will
attempt a write to the .rodata section and crash the kernel during boot or
module load.

> +			reset_ddebug_call_count();
> +			continue;
> +		}
> +
>  		if (modname)
>  			v2pr_info("query %d: module %s \"%s\"\n", i, modname, query);
>  		else

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260923-dd-cmap-part2-clean-v11-0-9b6c217fdf2f@gmail.com?part=37