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Wysocki" , Viresh Kumar Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Yuho Choi Subject: [PATCH v2] cpufreq: pcc: fix use-after-free and double free in _OSC evaluation Date: Thu, 16 Apr 2026 10:46:21 -0400 Message-ID: <20260416144621.93964-1-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: quoted-printable Content-Type: text/plain; charset="utf-8" pcc_cpufreq_do_osc() calls acpi_evaluate_object() twice for the two-phase _OSC negotiation. Between the two calls it freed output.pointer but left output.length unchanged. Since acpi_evaluate_object() treats a non-zero length with a non-NULL pointer as an existing buffer to write into, the second call wrote into freed memory (use-after-free). The subsequent kfree(output.pointer) at out_free then freed the same pointer a second time (double free). Reset output.pointer to NULL and output.length to ACPI_ALLOCATE_BUFFER after freeing the first result, so ACPICA allocates a fresh buffer for each phase independently. Fixes: 0f1d683fb35d ("[CPUFREQ] Processor Clocking Control interface driver= ") Signed-off-by: Yuho Choi Reviewed-by: Zhongqiu Han --- Changes in v1: - Drop spurious #include "acpi/actypes.h" (Zhongqiu Han) - Keep kfree() between the two calls and reset output.pointer =3D NULL and output.length =3D ACPI_ALLOCATE_BUFFER drivers/cpufreq/pcc-cpufreq.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c index ac2e90a65f0c4..a355ec4f3dd4c 100644 --- a/drivers/cpufreq/pcc-cpufreq.c +++ b/drivers/cpufreq/pcc-cpufreq.c @@ -352,6 +352,8 @@ static int __init pcc_cpufreq_do_osc(acpi_handle *handl= e) } =20 kfree(output.pointer); + output.pointer =3D NULL; + output.length =3D ACPI_ALLOCATE_BUFFER; capabilities[0] =3D 0x0; capabilities[1] =3D 0x1; =20 --=20 2.50.1 (Apple Git-155)