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Thu, 30 Jul 2026 23:17:11 -0700 (PDT) X-Received: by 2002:a17:903:4b50:b0:2c8:2808:3ec4 with SMTP id d9443c01a7336-2d046e7c719mr8401225ad.24.1785478631128; Thu, 30 Jul 2026 23:17:11 -0700 (PDT) Received: from [10.204.78.242] ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d04b0eb486sm799165ad.53.2026.07.30.23.17.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jul 2026 23:17:10 -0700 (PDT) Message-ID: Date: Fri, 31 Jul 2026 11:47:07 +0530 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] misc: fastrpc: remove mmap entry before remote unmap To: Yousef Alhouseen , Srinivas Kandagatla , Amol Maheshwari Cc: Arnd Bergmann , Greg Kroah-Hartman , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20260624174652.6792-1-alhouseenyousef@gmail.com> Content-Language: en-US From: Ekansh Gupta In-Reply-To: <20260624174652.6792-1-alhouseenyousef@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=BcLoFLt2 c=1 sm=1 tr=0 ts=6a6c3de8 cx=c_pps a=cmESyDAEBpBGqyK7t0alAg==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=kqHp1m7fC-4U1ryjZVsA:9 a=QEXdDO2ut3YA:10 a=1OuFwYUASf3TG4hYMiVC:22 X-Proofpoint-ORIG-GUID: 1ylLgr9idcyCdnollRgtG0GThmksgT2Z X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMxMDA0MiBTYWx0ZWRfX/+e01njGNSDk sp4wlCyrhLKhFuRtbcceA+Fq0B/AWVCWaV+t1Pf/wuxlcWM9q2a3xRV74d1bTtxpq1YnLkGSZTb +vMTJTQfA76yovkSzCtjwx8MbOxXhD4= X-Proofpoint-GUID: 1ylLgr9idcyCdnollRgtG0GThmksgT2Z X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMxMDA0MiBTYWx0ZWRfX8vRu9YOoeWQX W4Lv3BXFQojYZ0Y40fg9pkknIv5MVWmc9QMepsVCMBmWMfoIaN7wexSpRZCNpvGzNikEmfUbH9E RcFcdQ56h3Tl8BPsxdJb4Bf269GJyVGY/0Imztyy31y5ow/C6imfFlx67v8wwQehyi/eMUpZFjN X8ICBNx4ju/dzHqHuuJIkOqzK6E/gp4xRmIyokxhOHtDuTalT8R2KlMwoH3XFVuyNzc3NnVB7ie Mvuqar4JxfTY4EVqjnYqkwPy1rE/5N3Q6zyl3QZS8g9Uog0mWDJ9YTyQ/wUNjf9urHNjqnPvjq1 ULCtiMAbxDNX3PQzftAdP+xfu2SvnrpXbEFOjRmGxKx0crM8L1Ez7UPg84Td4n3lGSuuQU0Aew+ KYNr+OHGXfr8QYJ1VTMH5XbKRQFJUOhzBdqMl7APlr9MI2Hu8Hv0FIHPrbXNKlgoh5th06ZOG9W /0Qa06ZTjhKXg08O64A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-31_02,2026-07-30_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 clxscore=1015 spamscore=0 bulkscore=0 phishscore=0 adultscore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607310042 On 24-06-2026 23:16, Yousef Alhouseen wrote: > FASTRPC_IOCTL_MUNMAP looked up a buffer and dropped fl->lock. > > It only deleted the list entry after the remote unmap succeeded. > > Two threads can therefore find the same entry and unmap it twice. > > That can lead to a double list deletion and double free. > > Detach the entry before invoking the DSP. > > Put it back if the remote unmap fails. > There was a fix that got recently merged to fix the same problem[1]. Please check it and let me know if your change still holds. [1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/misc/fastrpc.c?id=902b8ec9dd1098cc133cffa8be0b6378544f27ba //ekansh> Signed-off-by: Yousef Alhouseen > --- > drivers/misc/fastrpc.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index ba4ade874..6a5239b1c 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -1902,7 +1902,8 @@ static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, struct fastrpc_buf * > if (!err) { > dev_dbg(dev, "unmmap\tpt 0x%09lx OK\n", buf->raddr); > spin_lock(&fl->lock); > - list_del(&buf->node); > + if (!list_empty(&buf->node)) > + list_del_init(&buf->node); > spin_unlock(&fl->lock); > fastrpc_buf_free(buf); > } else { > @@ -1917,6 +1918,7 @@ static int fastrpc_req_munmap(struct fastrpc_user *fl, char __user *argp) > struct fastrpc_buf *buf = NULL, *iter, *b; > struct fastrpc_req_munmap req; > struct device *dev = fl->sctx->dev; > + int err; > > if (copy_from_user(&req, argp, sizeof(req))) > return -EFAULT; > @@ -1925,6 +1927,7 @@ static int fastrpc_req_munmap(struct fastrpc_user *fl, char __user *argp) > list_for_each_entry_safe(iter, b, &fl->mmaps, node) { > if ((iter->raddr == req.vaddrout) && (iter->size == req.size)) { > buf = iter; > + list_del_init(&buf->node); > break; > } > } > @@ -1936,7 +1939,14 @@ static int fastrpc_req_munmap(struct fastrpc_user *fl, char __user *argp) > return -EINVAL; > } > > - return fastrpc_req_munmap_impl(fl, buf); > + err = fastrpc_req_munmap_impl(fl, buf); > + if (err) { > + spin_lock(&fl->lock); > + list_add_tail(&buf->node, &fl->mmaps); > + spin_unlock(&fl->lock); > + } > + > + return err; > } > > static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)