[PATCH 5.4 0/2] media: vim2m: Fix potential NULL pointer dereference

[Mark-PK Tsai]

Backport upstream solution [1][2] to fix below kernel panic:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000208
...
pc : _raw_spin_lock_irqsave+0x50/0x90
lr : v4l2_m2m_cancel_job+0x38/0x1c4 [v4l2_mem2mem]
sp : ffffffc012d2bcb0
x29: ffffffc012d2bcb0 x28: ffffff8098d6bb00
x27: 0000000000000000 x26: ffffffc01009b5c8
x25: 00000000000e001f x24: ffffff808ff3eb50
x23: ffffffc01009f5a0 x22: 0000000000000000
x21: ffffff808ffef000 x20: 0000000000000208
x19: 0000000000000000 x18: ffffffc012b51048
x17: ffffffc011e0ef7c x16: 00000000000000c0
x15: ffffffc010fc78f4 x14: ffffffc0119dd790
x13: 0000000000001b26 x12: 0000000053555555
x11: 0000000000000002 x10: 0000000000000001
x9 : 0000000000000000 x8 : 0000000000000208
x7 : 2020202020202020 x6 : ffffffc011e313a6
x5 : 0000000000000000 x4 : 0000000000000008
x3 : 000000000000002e x2 : 0000000000000001
x1 : 0000000000000000 x0 : 0000000000000208
Call trace:
 _raw_spin_lock_irqsave+0x50/0x90
 v4l2_m2m_cancel_job+0x38/0x1c4 [v4l2_mem2mem]
 v4l2_m2m_ctx_release+0x38/0x60 [v4l2_mem2mem]
 vim2m_release+0x5c/0xe0 [vim2m]
 v4l2_release+0x90/0x18c
 __fput+0xdc/0x2cc
 ____fput+0x10/0x1c
 task_work_run+0xc4/0x130
 do_notify_resume+0xdc/0x158
 work_pending+0x8/0x10

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cf7f34777a5b4100a3a44ff95f3d949c62892bdd
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1a28dce222a6ece725689ad58c0cf4a1b48894f4

Mark-PK Tsai (2):
  media: vim2m: Register video device after setting up internals
  media: vim2m: initialize the media device earlier

 drivers/media/platform/vim2m.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

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2.18.0