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[85.130.200.168]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490ea83d8dasm52501375e9.11.2026.06.11.23.25.40 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 11 Jun 2026 23:25:41 -0700 (PDT) From: Elazar Leibovich To: linux-pm@vger.kernel.org Cc: "Rafael J . Wysocki" , Daniel Lezcano , Lukasz Luba , linux-kernel@vger.kernel.org, Sivan Zohar-Kotzer , Elazar Leibovich Subject: [PATCH 1/2] powercap: dtpm_cpu: Fix out-of-bounds read in set_pd_power_limit() Date: Fri, 12 Jun 2026 09:25:35 +0300 Message-ID: <20260612062536.9147-2-elazarl@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260612062536.9147-1-elazarl@gmail.com> References: <20260612062536.9147-1-elazarl@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Sivan Zohar-Kotzer The loop in set_pd_power_limit() looks for the first perf state whose power exceeds the requested limit, then uses table[i - 1]. If the very first perf state already exceeds the limit, the loop breaks at i == 0 and table[-1] is read out of bounds. The powercap core clamps the requested limit to dtpm->power_min, but power_min was computed by update_pd_power_uw() with the number of online CPUs at that time. If CPUs have come online since the last update, the clamped limit can still be below table[0].power * nr_cpus, making the underflow reachable. Start the scan at index 1 so the lowest perf state is used as the fallback when even it exceeds the requested limit. Fixes: 0e8f68d7f048 ("powercap/drivers/dtpm: Add CPU energy model based support") Signed-off-by: Sivan Zohar-Kotzer Co-developed-by: Elazar Leibovich Signed-off-by: Elazar Leibovich --- drivers/powercap/dtpm_cpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c index 0a460f97bf15..5e06909ae4fc 100644 --- a/drivers/powercap/dtpm_cpu.c +++ b/drivers/powercap/dtpm_cpu.c @@ -54,7 +54,7 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit) rcu_read_lock(); table = em_perf_state_from_pd(pd); - for (i = 0; i < pd->nr_perf_states; i++) { + for (i = 1; i < pd->nr_perf_states; i++) { power = table[i].power * nr_cpus; -- 2.50.1 (Apple Git-155)