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Wed, 19 Aug 2026 21:30:59 -0700 (PDT) X-Received: by 2002:a17:902:fd8f:b0:2c9:df1b:e948 with SMTP id d9443c01a7336-2d5fd5cee10mr198914735ad.4.1787200259383; Wed, 19 Aug 2026 21:30:59 -0700 (PDT) Received: from [10.219.56.166] ([202.46.23.19]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d62d58a897sm1806855ad.27.2026.08.19.21.30.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 19 Aug 2026 21:30:58 -0700 (PDT) Message-ID: <7e025cc8-bdd8-4247-923d-821089a8457c@oss.qualcomm.com> Date: Thu, 20 Aug 2026 10:00:51 +0530 Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] misc: fastrpc: avoid duplicate DMA mappings in fastrpc_create_maps() To: Jianping Li , Srinivas Kandagatla Cc: Arnd Bergmann , Greg Kroah-Hartman , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Ling Xu , Dmitry Baryshkov , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, quic_chennak@quicinc.com, stable@kernel.org References: <20260805060940.41414-1-jianping.li@oss.qualcomm.com> Content-Language: en-US From: Ekansh Gupta In-Reply-To: <20260805060940.41414-1-jianping.li@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=E5/9Y6dl c=1 sm=1 tr=0 ts=6a868304 cx=c_pps a=MTSHoo12Qbhz2p7MsH1ifg==:117 a=j4ogTh8yFefVWWEFDRgCtg==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=CeeczvWzjZu7FbgsozkA:9 a=QEXdDO2ut3YA:10 a=GvdueXVYPmCkWapjIL-Q:22 X-Proofpoint-GUID: ivQkFE6nWlDtrgYJv4C6OltLm7AzXrFu X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODIwMDAyOSBTYWx0ZWRfXzVJPCAw1XJdk ftkDhEZRYzTvyQ9py7FR+UrnrHfekwYL910JbgFhTKaSoU9hwKPABiqVh4E+i9TQX62H0FPeEKN lRvZMLNOgwWICc9UzUi7zYxI6C9c7meIqyIIRbfkq87LeVYFFHqXCc6lcG8nZ5rJi/cJBy7tqch PHdqvkQ5ykUo3NSKVFjUekxZpK/vKYxHt3ssUkWIN6eKf31AmSDaTL6RB+s7v6j66F3v/kLCubf uDiuWa0eVuv5oPeTYkeF02KA9QIxuJk1pryxQgEjf2WHU4O4IeguORlhNuJKWTVHkz/bNZpKtmB Nz1E7Tzm1Q9f/unPzPDVU/i87gPNdQouesegY8Wvi6fTOVBNEXrxjYrp+WleHMyOKb6cluLS60B XtC+KKA/kneUYN6dzPHFJ8lIrHvVDcVXyxnjfJybbKfGemWMTGe4Grj0mkAxTfO8vDonOxe6EZ3 FtpUR9DGI76al0Pjq9w== X-Proofpoint-ORIG-GUID: ivQkFE6nWlDtrgYJv4C6OltLm7AzXrFu X-Proofpoint-Spam-Info: AW1haW4tMjYwODIwMDAyOSBTYWx0ZWRfXwxFZofpGxfMh E4o2bNrb6ECCqHCS68EPRBx86BCKuz13v1/cXPhP9xZJ41u+aLVbrdLvSxd9TG6i+pPdMnnag1T 8bRiOMTFofoQUSpylIOXuToKVxKeNnk= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-19_06,2026-08-19_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 adultscore=0 priorityscore=1501 suspectscore=0 phishscore=0 bulkscore=0 malwarescore=0 lowpriorityscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608200029 On 05-08-2026 11:39, Jianping Li wrote: > DMA handles passed as invoke arguments (scalars beyond nbufs) may refer > to the same dma_buf fd as an input/output buffer argument. Taking an > extra reference for such DMA handle maps leads to duplicate mappings and > an unbalanced reference count, since DMA handle maps are released > separately when the DSP returns the fd through the fdlist. > > Fix this by not taking an extra reference for DMA handle arguments > (take_ref = false) and tagging them with FASTRPC_MAP_DMA_HANDLE. As > these maps are borrowed references, fastrpc_get_args() re-validates the > map via fastrpc_map_lookup() before dereferencing it, so it is not used > after being freed. fastrpc_put_args() only releases maps flagged as > FASTRPC_MAP_DMA_HANDLE and clears the flag to guarantee the map is freed > exactly once. > > Also reject FASTRPC_MAP_DMA_HANDLE in fastrpc_req_mem_map(), since such > handles are already mapped implicitly during the remote invoke call and > must not be mapped again through the explicit MEM_MAP path. > > Fixes: 10df039834f84 ("misc: fastrpc: Skip reference for DMA handles") > Cc: stable@kernel.org > Signed-off-by: Jianping Li Reviewed-by: Ekansh Gupta