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([2601:282:1e02:1040:856a:da39:d9b3:fb8f]) by smtp.googlemail.com with ESMTPSA id 586e51a60fabf-440d9509e0esm7909565fac.14.2026.06.05.07.34.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Jun 2026 07:34:55 -0700 (PDT) Message-ID: Date: Fri, 5 Jun 2026 08:34:53 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/5] perf sched: Cap max_cpu at MAX_CPUS in timehist sample processing Content-Language: en-US To: Arnaldo Carvalho de Melo , Namhyung Kim Cc: Ingo Molnar , Thomas Gleixner , James Clark , Jiri Olsa , Ian Rogers , Adrian Hunter , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , sashiko-bot , "Claude Opus 4.6" References: <20260605121515.1725549-1-acme@kernel.org> <20260605121515.1725549-5-acme@kernel.org> From: David Ahern In-Reply-To: <20260605121515.1725549-5-acme@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/5/26 6:15 AM, Arnaldo Carvalho de Melo wrote: > From: Arnaldo Carvalho de Melo > > perf_timehist__process_sample() updates sched->max_cpu from the > sample CPU without bounds checking. Later code uses max_cpu + 1 as > an iteration count over arrays allocated with MAX_CPUS entries > (curr_thread, cpu_last_switched). A recording with CPU IDs >= MAX_CPUS > causes out-of-bounds array accesses. > > Also cap the env->nr_cpus_online initialization of max_cpu in > perf_sched__timehist(), which could exceed MAX_CPUS on very large > systems. > > Add bounds checks before both max_cpu updates, matching the pattern > already used in map_switch_event(). > > Fixes: 49394a2a24c7 ("perf sched timehist: Introduce timehist command") > Reported-by: sashiko-bot > Cc: David Ahern > Assisted-by: Claude Opus 4.6 > Signed-off-by: Arnaldo Carvalho de Melo > --- > tools/perf/builtin-sched.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > LGTM Reviewed-by: David Ahern