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([240e:404:2520:fc28:96c:a6d:1e5e:8796]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82f8e981a0asm258949b3a.3.2026.04.16.20.29.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Apr 2026 20:29:08 -0700 (PDT) Message-ID: <203f2e52-bf9d-4055-88bd-d911bfecf082@oss.qualcomm.com> Date: Fri, 17 Apr 2026 11:29:04 +0800 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 v2] cpufreq: pcc: fix use-after-free and double free in _OSC evaluation To: Yuho Choi , "Rafael J . Wysocki" , Viresh Kumar Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, zhongqiu.han@oss.qualcomm.com References: <20260416144621.93964-1-dbgh9129@gmail.com> Content-Language: en-US From: Zhongqiu Han In-Reply-To: <20260416144621.93964-1-dbgh9129@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: LmWvgfxCCfCftYN9zQrCbwQ-6azLtoOE X-Proofpoint-ORIG-GUID: LmWvgfxCCfCftYN9zQrCbwQ-6azLtoOE X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE3MDAzMSBTYWx0ZWRfXzj7ybp/8r6eO wcbXlE6lPref7ogit70kI+p5jSNKetCGI2kAI0wyaXSLJfgS4ePfrpbOdMXd1/AmDQXVr97B8v+ KMiqf50E9OW08y95BtVa5mtNlDmJ/Vr4AI/RiufE3YXX+R0hQV0pQZK1wVJJcmq6e7Vep1EGbx2 nqvcazGUPgJjLulUKbDUo99GBvDwuwKw8n1eGRprMxm7pUPQTZd8EnfPsmpBOmhcfJWBtoqsKYH UMew4pMAc/VBdijYVRmEVcOHz7Njhg5q8jHSjqxnOkwRlpfd738l9HY+0FAc3mRsHxYBRw+6n6M gOAG2ywEZUvEVjcdMmf4eLbSD2vdOWqpVLVw7c0WlFN6Y87P2ReLJdbVgJVtT9qu67tEQwn9qKY 78DUk+q+tN0cMJ7RZip2/Fanb6nvzGj21A8IJBPL4ANsPG0YEwjw4EKvdJSRE2+/TXTuftFJypw eg0gMvRPi1O51wXuG0Q== X-Authority-Analysis: v=2.4 cv=YtE/gYYX c=1 sm=1 tr=0 ts=69e1a906 cx=c_pps a=Qgeoaf8Lrialg5Z894R3/Q==:117 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=pGLkceISAAAA:8 a=EUspDBNiAAAA:8 a=aIcA-GvUrLZ_5u2auIMA:9 a=QEXdDO2ut3YA:10 a=x9snwWr2DeNwDh03kgHS:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-16_04,2026-04-16_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 adultscore=0 malwarescore=0 clxscore=1015 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604170031 On 4/16/2026 10:46 PM, Yuho Choi wrote: > 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 = NULL > and output.length = 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 *handle) > } > > kfree(output.pointer); > + output.pointer = NULL; > + output.length = ACPI_ALLOCATE_BUFFER; > capabilities[0] = 0x0; > capabilities[1] = 0x1; > -- Thx and BRs, Zhongqiu Han