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Mon, 04 May 2026 10:17:10 -0700 (PDT) Received: from hu-mojha-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c7ffbc6f063sm10398240a12.20.2026.05.04.10.17.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 May 2026 10:17:10 -0700 (PDT) From: Mukesh Ojha To: Srinivas Kandagatla , Amol Maheshwari , Arnd Bergmann , Greg Kroah-Hartman , Thierry Escande Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Mukesh Ojha , stable@vger.kernel.org Subject: [PATCH v2 1/2] misc: fastrpc: Fix NULL pointer dereference in rpmsg callback Date: Mon, 4 May 2026 22:47:00 +0530 Message-ID: <20260504171701.18164-1-mukesh.ojha@oss.qualcomm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: N_x2xwkJx-5FZ5bBEi8Lr2F9f52EP4fs X-Authority-Analysis: v=2.4 cv=Z+vc2nRA c=1 sm=1 tr=0 ts=69f8d498 cx=c_pps a=rz3CxIlbcmazkYymdCej/Q==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=NGcC8JguVDcA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=MnYYGAq_QTRuFDU830wA:9 a=bFCP_H2QrGi7Okbo017w:22 X-Proofpoint-GUID: N_x2xwkJx-5FZ5bBEi8Lr2F9f52EP4fs X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA0MDE1NyBTYWx0ZWRfX3alqrfy6PneI 1+I5pGCG/qwxfQQGzG9fgU0kfGAue+HF8STwBgws1mSoaccq7PGEaUejm9AD1SN/0A273REuz95 t4bf3gmZHgmTNqqhlPU8fXD3xguFg9fXgypqGhHbVwXQW3YosD1DBAYCtQGVWeZxlZfWYzdnKpm WFjE952TyQ8bw9goTFviCTWkOyQvQuAXDmlEr0T2WC0WdJaBEK5jD2o5+wMaCB3EIRXcAyxtKhH 4qZgrQFvOx0eIRF3biejX4SRII5AtHb9Mp5B7zsF1plmC0toPToaILekHv1cueLs8t3TbyN3b6Z VyiZFS/ZM1nMbsT70Ut+pBS9PGAgXX7prfZyqDA9G09okQjR8aFFjnXXKrGtM1QYeKAQWg2cqvl vQQz+rNS0FyugUjnGFX+lOCKR5Y7rEHek4TA4mnpmP42IggZs/nrFpwPLRuAIafspE+m7bEErkX QR5k3rz1r+I4Gvz8vBg== 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=2026-05-04_05,2026-04-30_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 adultscore=0 impostorscore=0 malwarescore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605040157 A NULL pointer dereference was observed on Hawi at boot when the DSP sends a glink message before fastrpc_rpmsg_probe() has completed initialization: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000178 pc : _raw_spin_lock_irqsave+0x34/0x8c lr : fastrpc_rpmsg_callback+0x3c/0xcc [fastrpc] ... Call trace: _raw_spin_lock_irqsave+0x34/0x8c (P) fastrpc_rpmsg_callback+0x3c/0xcc [fastrpc] qcom_glink_native_rx+0x538/0x6a4 qcom_glink_smem_intr+0x14/0x24 [qcom_glink_smem] The faulting address 0x178 corresponds to the lock variable inside struct fastrpc_channel_ctx, confirming that cctx is NULL when fastrpc_rpmsg_callback() attempts to take the spinlock. There are two issues here. First, dev_set_drvdata() is called before spin_lock_init() and idr_init(), leaving a window where the callback can retrieve a valid cctx pointer but operate on an uninitialized spinlock. Second, the rpmsg channel becomes live as soon as the driver is bound, so fastrpc_rpmsg_callback() can fire before dev_set_drvdata() is called at all, resulting in dev_get_drvdata() returning NULL. Fix both issues by moving all cctx initialization ahead of dev_set_drvdata() so the structure is fully initialized before it becomes visible to the callback, and add a NULL check in fastrpc_rpmsg_callback() as a guard against any remaining window. Fixes: f6f9279f2bf0 ("misc: fastrpc: Add Qualcomm fastrpc basic driver model") Cc: stable@vger.kernel.org Signed-off-by: Mukesh Ojha --- Changes in v2: https://lore.kernel.org/lkml/20260417200146.184425-1-mukesh.ojha@oss.qualcomm.com/ - Added stable mailing list and fixes tag. drivers/misc/fastrpc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 1080f9acf70a..a1a54453bb7e 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -2431,7 +2431,6 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev) kref_init(&data->refcount); - dev_set_drvdata(&rpdev->dev, data); rdev->dma_mask = &data->dma_mask; dma_set_mask_and_coherent(rdev, DMA_BIT_MASK(32)); INIT_LIST_HEAD(&data->users); @@ -2440,6 +2439,7 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev) idr_init(&data->ctx_idr); data->domain_id = domain_id; data->rpdev = rpdev; + dev_set_drvdata(&rpdev->dev, data); err = of_platform_populate(rdev->of_node, NULL, NULL, rdev); if (err) @@ -2513,6 +2513,9 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data, if (len < sizeof(*rsp)) return -EINVAL; + if (!cctx) + return -ENODEV; + ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> 4); spin_lock_irqsave(&cctx->lock, flags); -- 2.53.0