vidioc_g_edid: BUG: Unable to handle kernel NULL pointer dereference at virtual address 00000716

[Naresh Kamboju]

v4l2-compliance test running on linux stable 4.9 reported kernel bug.
The crash is pointing to kernel module "vivid.ko" which was loaded by
test case. (  modprobe vivid.ko)

Test passes on 4.4, 4.14, 4.19 and 5.0.
steps to reproduce:

       # boot 4.9 kernel on x86_64 / Juno / hikey /  device
       #  install v4l-utils package
       # modprobe vivid.ko no_error_inj=1
       # v4l2-compliance -v -d /dev/video0
       # you will get BUG: Unable to handle kernel NULL pointer dereference

arm64 juno-r2 test output log,
----------------------------------------
INFO: Running v4l2-compliance device test...
[   48.574093] vivid-000: =================  START STATUS  =================
[   48.580866] vivid-000: Test Pattern: 75% Colorbar
...
[   48.730569] tpg RGB range: 0/2
[   48.733592] vivid-000: ==================  END STATUS  ==================
[   48.753649] BUG: Unable to handle kernel NULL pointer dereference
at virtual address 00000716
[   48.761689] pgd = ffff80094d113000
[   48.765097] [00000716] *pgd=00000009f4300003,
*pud=00000009f513c003, *pmd=0000000000000000
[   48.773666] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[   48.779186] Modules linked in: vivid videobuf2_vmalloc
videobuf2_memops v4l2_tpg videobuf2_v4l2 videobuf2_core fuse
[   48.789574] CPU: 5 PID: 2278 Comm: v4l2-compliance Not tainted 4.9.169-rc1 #1
[   48.796637] Hardware name: ARM Juno development board (r2) (DT)
[   48.802496] task: ffff8009741e5800 task.stack: ffff80096ec9c000
[   48.808405] PC is at vidioc_g_edid+0xb8/0x150 [vivid]
[   48.813445] LR is at vidioc_g_edid+0xb4/0x150 [vivid]
[   48.818444] pc : [<ffff000000bffc80>] lr : [<ffff000000bffc7c>]
pstate: 40000145
[   48.825764] sp : ffff80096ec9fbc0
[   48.829043] x29: ffff80096ec9fbc0 x28: 0000000000000000
[   48.834311] x27: ffff800972fd0590 x26: 0000000000000028
[   48.839580] x25: 0000000000000000 x24: ffff000009289eb0
[   48.844849] x23: ffff80096ec9fd10 x22: ffff80096ec9fd10
[   48.850118] x21: 0000000000000000 x20: ffff800972fd0000
[   48.855387] x19: ffff80096ec9fd10 x18: 0000ffffc63f1d4f
[   48.860656] x17: 0000ffffb0186910 x16: ffff0000082c9840
[   48.865924] x15: 000000000000000a x14: 2700000000000000
[   48.871193] x13: 0000001c0000321c x12: c000358040201cd0
[   48.876461] x11: 5180001d1a1a0000 x10: 321cc00035203040
[   48.881730] x9 : 1f3870a080361a1e x8 : 0000321cc0003520
[   48.886998] x7 : 30803e70f0a000d0 x6 : ffff800972dbdc00
[   48.892267] x5 : ffff800972ca0000 x4 : 0000000000000000
[   48.897534] x3 : 0000000000000002 x2 : ffffffffffffffc0
[   48.902803] x1 : ffff00000ba83100 x0 : ffff800972dbdb00
[   48.908069]
[   48.909543] Process v4l2-compliance (pid: 2278, stack limit =
0xffff80096ec9c020)
[   48.916951] Stack: (0xffff80096ec9fbc0 to 0xffff80096eca0000)
[   48.922642] fbc0: ffff80096ec9fbf0 ffff000008900194
00000000c0285628 ffff80097537aa80
...
...
...
[   49.272633] [<ffff000000bffc80>] vidioc_g_edid+0xb8/0x150 [vivid]
[   49.278672] [<ffff000008900194>] __video_do_ioctl+0x204/0x2f8
[   49.284362] [<ffff0000088ff990>] video_usercopy+0x230/0x7e0
[   49.289879] [<ffff0000088fff7c>] video_ioctl2+0x3c/0x50
[   49.295052] [<ffff0000088fa394>] v4l2_ioctl+0x8c/0x128
[   49.300143] [<ffff0000082c9060>] do_vfs_ioctl+0xb0/0x890
[   49.305404] [<ffff0000082c98cc>] SyS_ioctl+0x8c/0xa8
[   49.310321] [<ffff0000080841dc>] __sys_trace_return+0x0/0x4
[   49.315841] Code: 53196042 f9401260 95e37502 f9401260 (794e2ea2)
[   49.321877] ---[ end trace 2f24332f5b488208 ]---


Full test log,
https://qa-reports.linaro.org/lkft/linux-stable-rc-4.9-oe/build/v4.9.168-78-g6ecae2ce7b5a/testrun/680319/log

Linux kernel version,
Linux version 4.9.169-rc1 (oe-user@oe-host) (gcc version 7.3.0 (GCC) )
#1 SMP Tue Apr 16 18:34:31 UTC 2019

Code snippet:
long video_ioctl2(struct file *file,
      unsigned int cmd, unsigned long arg)
{
return video_usercopy(file, cmd, arg, __video_do_ioctl);
}
EXPORT_SYMBOL(video_ioctl2);


Test logs from each device,
Juno-r2: arm64
https://lkft.validation.linaro.org/scheduler/job/680319#L1389

X86_64:
https://lkft.validation.linaro.org/scheduler/job/680361#L1143

Hikey: arm64
https://lkft.validation.linaro.org/scheduler/job/680287#L1564

BeagleBoard-x15: arm32
https://lkft.validation.linaro.org/scheduler/job/680377#L1540

Best regards
Naresh Kamboju