CVE-2021-47413

Description

In the Linux kernel, the following vulnerability has been resolved: usb: chipidea: ci_hdrc_imx: Also search for 'phys' phandle When passing 'phys' in the devicetree to describe the USB PHY phandle (which is the recommended way according to Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt) the following NULL pointer dereference is observed on i.MX7 and i.MX8MM: [ 1.489344] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098 [ 1.498170] Mem abort info: [ 1.500966] ESR = 0x96000044 [ 1.504030] EC = 0x25: DABT (current EL), IL = 32 bits [ 1.509356] SET = 0, FnV = 0 [ 1.512416] EA = 0, S1PTW = 0 [ 1.515569] FSC = 0x04: level 0 translation fault [ 1.520458] Data abort info: [ 1.523349] ISV = 0, ISS = 0x00000044 [ 1.527196] CM = 0, WnR = 1 [ 1.530176] [0000000000000098] user address but active_mm is swapper [ 1.536544] Internal error: Oops: 96000044 [#1] PREEMPT SMP [ 1.542125] Modules linked in: [ 1.545190] CPU: 3 PID: 7 Comm: kworker/u8:0 Not tainted 5.14.0-dirty #3 [ 1.551901] Hardware name: Kontron i.MX8MM N801X S (DT) [ 1.557133] Workqueue: events_unbound deferred_probe_work_func [ 1.562984] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) [ 1.568998] pc : imx7d_charger_detection+0x3f0/0x510 [ 1.573973] lr : imx7d_charger_detection+0x22c/0x510 This happens because the charger functions check for the phy presence inside the imx_usbmisc_data structure (data->usb_phy), but the chipidea core populates the usb_phy passed via 'phys' inside 'struct ci_hdrc' (ci->usb_phy) instead. This causes the NULL pointer dereference inside imx7d_charger_detection(). Fix it by also searching for 'phys' in case 'fsl,usbphy' is not found. Tested on a imx7s-warp board.

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://www.suse.com/security/cve/CVE-2021-47413.html
• https://security-tracker.debian.org/tracker/CVE-2021-47413