Re: [PATCH v1] perf stat: Avoid uninitialized memory read on error

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Atomic Conclusion: Unchecked ERR_PTR from hashmap__new() causes predictable application crashes. The return value is incorrectly checked against NULL instead of IS_ERR().
--

commit 525c560536a62c39331ec585b1ce897decf7179c
Author: Ian Rogers <irogers@google.com>

perf stat: Avoid uninitialized memory read on error
    
If has_supported_counters fails then msg was passed to ui__error
regardless of whether an error was written into msg leading to reading
uninitialized memory. Avoid this by always terminating msg at
initialization.

> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index c50cf230f16ed..37752d6bfef45 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c

[ ... ]

[Severity: High]
This isn't a bug introduced by this patch, but I noticed that the return
value of hashmap__new() is incorrectly checked against NULL instead of
IS_ERR().

Since hashmap__new() returns an ERR_PTR on failure, this will
cause predictable crashes under memory pressure instead of graceful error
handling.

For example, in tools/perf/util/pmu.c:perf_pmu__init():

        pmu->aliases = hashmap__new(aliases__hash, aliases__equal, /*ctx=*/ NULL);
        if (!pmu->aliases)
                return -ENOMEM;

And similarly in tools/perf/util/pmu.c:perf_pmu__create_placeholder_core_pmu():

        pmu->aliases = hashmap__new(aliases__hash, aliases__equal, /*ctx=*/ NULL);
        INIT_LIST_HEAD(&pmu->caps);

Also in tools/perf/util/fncache.c:fncache__init():

        fncache = hashmap__new(fncache__hash, fncache__equal, /*ctx=*/NULL);

Should these locations be updated to use IS_ERR() when validating the result
of hashmap__new()?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260908220720.564614-1-irogers@google.com?part=1