CVE-2022-50560 — drm/meson: explicitly remove aggregate driver at module unload time

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

drm/meson: explicitly remove aggregate driver at module unload time

Because component_master_del wasn't being called when unloading the meson_drm module, the aggregate device would linger forever in the global aggregate_devices list. That means when unloading and reloading the meson_dw_hdmi module, component_add would call into try_to_bring_up_aggregate_device and find the unbound meson_drm aggregate device.

This would in turn dereference some of the aggregate_device's struct entries which point to memory automatically freed by the devres API when unbinding the aggregate device from meson_drv_unbind, and trigger an use-after-free bug:

[ +0.000014] ============================================================= [ +0.000007] BUG: KASAN: use-after-free in find_components+0x468/0x500 [ +0.000017] Read of size 8 at addr ffff000006731688 by task modprobe/2536 [ +0.000018] CPU: 4 PID: 2536 Comm: modprobe Tainted: G C O 5.19.0-rc6-lrmbkasan+ #1 [ +0.000010] Hardware name: Hardkernel ODROID-N2Plus (DT) [ +0.000008] Call trace: [ +0.000005] dump_backtrace+0x1ec/0x280 [ +0.000011] show_stack+0x24/0x80 [ +0.000007] dump_stack_lvl+0x98/0xd4 [ +0.000010] print_address_description.constprop.0+0x80/0x520 [ +0.000011] print_report+0x128/0x260 [ +0.000007] kasan_report+0xb8/0xfc [ +0.000007] __asan_report_load8_noabort+0x3c/0x50 [ +0.000009] find_components+0x468/0x500 [ +0.000008] try_t…

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CVE-2022-50560 — drm/meson: explicitly remove aggregate driver at module unload time