CVE-2024-50175

Published Nov 8, 2024

Last updated 2 years ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: media: qcom: camss: Remove use_count guard in stop_streaming The use_count check was introduced so that multiple concurrent Raw Data Interfaces RDIs could be driven by different virtual channels VCs on the CSIPHY input driving the video pipeline. This is an invalid use of use_count though as use_count pertains to the number of times a video entity has been opened by user-space not the number of active streams. If use_count and stream-on count don't agree then stop_streaming() will break as is currently the case and has become apparent when using CAMSS with libcamera's released softisp 0.3. The use of use_count like this is a bit hacky and right now breaks regular usage of CAMSS for a single stream case. Stopping qcam results in the splat below, and then it cannot be started again and any attempts to do so fails with -EBUSY. [ 1265.509831] WARNING: CPU: 5 PID: 919 at drivers/media/common/videobuf2/videobuf2-core.c:2183 __vb2_queue_cancel+0x230/0x2c8 [videobuf2_common] ... [ 1265.510630] Call trace: [ 1265.510636] __vb2_queue_cancel+0x230/0x2c8 [videobuf2_common] [ 1265.510648] vb2_core_streamoff+0x24/0xcc [videobuf2_common] [ 1265.510660] vb2_ioctl_streamoff+0x5c/0xa8 [videobuf2_v4l2] [ 1265.510673] v4l_streamoff+0x24/0x30 [videodev] [ 1265.510707] __video_do_ioctl+0x190/0x3f4 [videodev] [ 1265.510732] video_usercopy+0x304/0x8c4 [videodev] [ 1265.510757] video_ioctl2+0x18/0x34 [videodev] [ 1265.510782] v4l2_ioctl+0x40/0x60 [videodev] ... [ 1265.510944] videobuf2_common: driver bug: stop_streaming operation is leaving buffer 0 in active state [ 1265.511175] videobuf2_common: driver bug: stop_streaming operation is leaving buffer 1 in active state [ 1265.511398] videobuf2_common: driver bug: stop_streaming operation is leaving buffer 2 in active st One CAMSS specific way to handle multiple VCs on the same RDI might be: - Reference count each pipeline enable for CSIPHY, CSID, VFE and RDIx. - The video buffers are already associated with msm_vfeN_rdiX so release video buffers when told to do so by stop_streaming. - Only release the power-domains for the CSIPHY, CSID and VFE when their internal refcounts drop. Either way refusing to release video buffers based on use_count is erroneous and should be reverted. The silicon enabling code for selecting VCs is perfectly fine. Its a "known missing feature" that concurrent VCs won't work with CAMSS right now. Initial testing with this code didn't show an error but, SoftISP and "real" usage with Google Hangouts breaks the upstream code pretty quickly, we need to do a partial revert and take another pass at VCs. This commit partially reverts commit 89013969e232 ("media: camss: sm8250: Pipeline starting and stopping for multiple virtual channels")
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: coresight: tmc-etr: Fix race condition between sysfs and perf mode When trying to run perf and sysfs mode simultaneously, the WARN_ON() in tmc_etr_enable_hw() is triggered sometimes: WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] [..snip..] Call trace: tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] coresight_enable_path+0x1c8/0x218 [coresight] coresight_enable_sysfs+0xa4/0x228 [coresight] enable_source_store+0x58/0xa8 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2c8/0x388 ksys_write+0x74/0x108 __arm64_sys_write+0x24/0x38 el0_svc_common.constprop.0+0x64/0x148 do_el0_svc+0x24/0x38 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xc8/0xd0 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Since the enablement of sysfs mode is separeted into two critical regions, one for sysfs buffer allocation and another for hardware enablement, it's possible to race with the perf mode. Fix this by double check whether the perf mode's been used before enabling the hardware in sysfs mode. mode: [sysfs mode] [perf mode] tmc_etr_get_sysfs_buffer() spin_lock(&drvdata->spinlock) [sysfs buffer allocation] spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() drvdata->etr_buf = etr_perf->etr_buf spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at the perf side spin_unlock(&drvdata->spinlock) With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf. This ensures we verify whether the perf mode's already running before we actually allocate the buffer. Then we can save the time of allocating/freeing the sysfs buffer if race with the perf mode.CVE-2026-46272