cbcvebase.
CVE-2024-26909
published 2024-04-17

CVE-2024-26909: In the Linux kernel, the following vulnerability has been resolved: soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free A recent DRM series purporting…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.24%
14.7th percentile
In the Linux kernel, the following vulnerability has been resolved: soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free A recent DRM series purporting to simplify support for "transparent bridges" and handling of probe deferrals ironically exposed a use-after-free issue on pmic_glink_altmode probe deferral. This has manifested itself as the display subsystem occasionally failing to initialise and NULL-pointer dereferences during boot of machines like the Lenovo ThinkPad X13s. Specifically, the dp-hpd bridge is currently registered before all resources have been acquired which means that it can also be deregistered on probe deferrals. In the meantime there is a race window where the new aux bridge driver (or PHY driver previously) may have looked up the dp-hpd bridge and stored a (non-reference-counted) pointer to the bridge which is about to be deallocated. When the display controller is later initialised, this triggers a use-after-free when attaching the bridges: dp -> aux -> dp-hpd (freed) which may, for example, result in the freed bridge failing to attach: [drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16 or a NULL-pointer dereference: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 ... Call trace: drm_bridge_attach+0x70/0x1a8 [drm] drm_aux_bridge_attach+0x24/0x38 [aux_bridge] drm_bridge_attach+0x80/0x1a8 [drm] dp_bridge_init+0xa8/0x15c [msm] msm_dp_modeset_init+0x28/0xc4 [msm] The DRM bridge implementation is clearly fragile and implicitly built on the assumption that bridges may never go away. In this case, the fix is to move the bridge registration in the pmic_glink_altmode driver to after all resources have been looked up. Incidentally, with the new dp-hpd bridge implementation, which registers child devices, this is also a requirement due to a long-standing issue in driver core that can otherwise lead to a probe deferral loop (see commit fbc35b4

Affected

13 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.7.12-1 (forky)linux 6.7.12-1 (forky)
linuxlinux
linuxlinux>= 080b4e24852b1d5b66929f69344e6c3eeb963941 < 2bbd65c6ca567ed8dbbfc4fb945f57ce64bef3422bbd65c6ca567ed8dbbfc4fb945f57ce64bef342
linuxlinux>= 080b4e24852b1d5b66929f69344e6c3eeb963941 < ef45aa2841e15b649e5417fe3d4de395fe462781ef45aa2841e15b649e5417fe3d4de395fe462781
linuxlinux>= 080b4e24852b1d5b66929f69344e6c3eeb963941 < b979f2d50a099f3402418d7ff5f26c3952fb08bbb979f2d50a099f3402418d7ff5f26c3952fb08bb
linuxlinux_kernel>= 0 < 6.7.12-16.7.12-1
linuxlinux_kernel>= 0 < 6.7.12-16.7.12-1
linuxlinux_kernel>= 6.3 < 6.6.236.6.23
linuxlinux_kernel>= 6.7 < 6.7.116.7.11
msrcazl3_kernel_6.6.22.1-2_on_azure_linux_3.0
msrcazl3_kernel_6.6.29.1-3_on_azure_linux_3.0
msrcazure_linux_3.0_arm
msrcazure_linux_3.0_x64

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5LOW
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
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