Re: [PATCH perf-tools-next 1/3] perf trace: Introduce kernel symbol beautifier for virtual addresses

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Memory leak of reference-counted `struct map` handle in `syscall_arg__scnprintf_ksym`.
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--- Patch [1]: [PATCH perf-tools-next 1/3] perf trace: Introduce kernel symbol beautifier for virtual addresses ---
commit 0ff39d14d9508d5e3c586057a78b07cbcda7f7fb
Author: Aaron Tomlin <[email protected]>

perf trace: Introduce kernel symbol beautifier for virtual addresses

This commit adds a kernel symbol beautifier for perf trace to translate
raw kernel virtual addresses into human-readable symbol names and offsets.
It uses machine__find_kernel_symbol() to look up the symbols dynamically.

> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index c3c7f1f85c530..102221b301a54 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c

[ ... ]

> @@ -750,6 +750,30 @@ size_t syscall_arg__scnprintf_ptr(char *bf, size_t size, struct syscall_arg *arg
>  	return syscall_arg__scnprintf_hex(bf, size, arg);
>  }
>  
> +size_t syscall_arg__scnprintf_ksym(char *bf, size_t size, struct syscall_arg *arg)
> +{
> +	if (arg->val == 0)
> +		return scnprintf(bf, size, "NULL");
> +
> +	if (arg->trace && arg->trace->host) {
> +		struct map *map;
> +		struct symbol *sym = machine__find_kernel_symbol(arg->trace->host,
> +								 arg->val, &map);
> +
> +		if (sym) {
> +			u64 start = map__unmap_ip(map, sym->start);
> +			u64 offset = arg->val - start;
> +
> +			if (offset == 0)
> +				return scnprintf(bf, size, "%s", sym->name);
> +			return scnprintf(bf, size, "%s+0x%" PRIx64,
> +					 sym->name, offset);

[Severity: High]
Does this code leak the struct map reference?

When machine__find_kernel_symbol() populates the map pointer, it acquires a
reference that the caller takes ownership of.

However, this function returns directly on both success paths and the fallback
path without calling map__put(map). This will cause a memory leak for every
formatted event that resolves to a valid map, which can quickly lead to memory
exhaustion or LSAN crashes when running perf trace.

> +		}
> +	}
> +
> +	return syscall_arg__scnprintf_hex(bf, size, arg);
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1