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Wysocki" , Viresh Kumar Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Yuho Choi Subject: [PATCH v1] cpufreq: pcc: fix use-after-free and double free in _OSC evaluation Date: Wed, 15 Apr 2026 12:51:39 -0400 Message-ID: <20260415165139.14113-1-dbgh9129@gmail.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit pcc_cpufreq_do_osc() evaluates _OSC twice with the same output buffer. The first acpi_evaluate_object() allocates the buffer because output is initialized with ACPI_ALLOCATE_BUFFER. Freeing output.pointer before the second evaluation leaves output.length stale, so the next call treats output as a caller-supplied buffer and performs a use-after-free write into the freed memory. The final cleanup path then frees the same pointer again, causing a double free. Keep the first _OSC result alive until the shared cleanup path and route the early error exits through out_free. This avoids both the use-after- free on the second evaluation and the final double free. Fixes: 0f1d683fb35d ("[CPUFREQ] Processor Clocking Control interface driver") Signed-off-by: Yuho Choi --- drivers/cpufreq/pcc-cpufreq.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c index ac2e90a65f0c4..165826b5d6844 100644 --- a/drivers/cpufreq/pcc-cpufreq.c +++ b/drivers/cpufreq/pcc-cpufreq.c @@ -23,6 +23,7 @@ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */ +#include "acpi/actypes.h" #include #include #include @@ -351,16 +352,19 @@ static int __init pcc_cpufreq_do_osc(acpi_handle *handle) goto out_free; } - kfree(output.pointer); capabilities[0] = 0x0; capabilities[1] = 0x1; status = acpi_evaluate_object(*handle, "_OSC", &input, &output); - if (ACPI_FAILURE(status)) - return -ENODEV; + if (ACPI_FAILURE(status)) { + ret = -ENODEV; + goto out_free; + } - if (!output.length) - return -ENODEV; + if (!output.length) { + ret = -ENODEV; + goto out_free; + } out_obj = output.pointer; if (out_obj->type != ACPI_TYPE_BUFFER) { -- 2.50.1 (Apple Git-155)