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

usb: dwc3: ep0: fix NULL pointer exception

There is no validation of the index from dwc3_wIndex_to_dep() and we might
be referring a non-existing ep and trigger a NULL pointer exception. In
certain configurations we might use fewer eps and the index might wrongly
indicate a larger ep index than existing.

By adding this validation from the patch we can actually report a wrong
index back to the caller.

In our usecase we are using a composite device on an older kernel, but
upstream might use this fix also. Unfortunately, I cannot describe the
hardware for others to reproduce the issue as it is a proprietary
implementation.

[   82.958261] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000a4
[   82.966891] Mem abort info:
[   82.969663]   ESR = 0x96000006
[   82.972703]   Exception class = DABT (current EL), IL = 32 bits
[   82.978603]   SET = 0, FnV = 0
[   82.981642]   EA = 0, S1PTW = 0
[   82.984765] Data abort info:
[   82.987631]   ISV = 0, ISS = 0x00000006
[   82.991449]   CM = 0, WnR = 0
[   82.994409] user pgtable: 4k pages, 39-bit VAs, pgdp = 00000000c6210ccc
[   83.000999] [00000000000000a4] pgd=0000000053aa5003, pud=0000000053aa5003, pmd=0000000000000000
[   83.009685] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[   83.026433] Process irq/62-dwc3 (pid: 303, stack limit = 0x000000003985154c)
[   83.033470] CPU: 0 PID: 303 Comm: irq/62-dwc3 Not tainted 4.19.124 #1
[   83.044836] pstate: 60000085 (nZCv daIf -PAN -UAO)
[   83.049628] pc : dwc3_ep0_handle_feature+0x414/0x43c
[   83.054558] lr : dwc3_ep0_interrupt+0x3b4/0xc94

...

[   83.141788] Call trace:
[   83.144227]  dwc3_ep0_handle_feature+0x414/0x43c
[   83.148823]  dwc3_ep0_interrupt+0x3b4/0xc94
[   83.181546] ---[ end trace aac6b5267d84c32f ]---

kernel.org https://git.kernel.org/stable/c/366369b89bedd59b1425386e8d4a18a466e420e4 [No types assigned]

kernel.org https://git.kernel.org/stable/c/470403639114895e2697c766fbe17be8d0e9b67a [No types assigned]

kernel.org https://git.kernel.org/stable/c/60156089f07e724e4dc8483702d5e1ede4522749 [No types assigned]

kernel.org https://git.kernel.org/stable/c/788755756dd4a6aba1de479fec20b0fa600e7f19 [No types assigned]

kernel.org https://git.kernel.org/stable/c/96b74a99d360235c24052f1d060e64ac53f43528 [No types assigned]

kernel.org https://git.kernel.org/stable/c/990dc90750772622d44ca2ea6652c521e6f67e16 [No types assigned]

kernel.org https://git.kernel.org/stable/c/bd551e7c85939de2182010273450bfa78c3742fc [No types assigned]

kernel.org https://git.kernel.org/stable/c/d00889080ab60051627dab1d85831cd9db750e2a [No types assigned]