[PATCH] Fix NULL pointer deref in nvme_ctrl_fast_io_fail_tmo_show

[Daniel Wagner]

On Tue, Apr 13, 2021 at 12:19:53PM +0530, Gopal Tiwari wrote:
> When accessing fast_io_fail_tmo from /sys hit kernel crash
> 
>  #7 [ffff9ddf82467d80] page_fault at ffffffff90e010fe
>     [exception RIP: nvme_ctrl_fast_io_fail_tmo_show+22]
>     RIP: ffffffffc0465116  RSP: ffff9ddf82467e38  RFLAGS: 00010286
>     RAX: 0000000000000000  RBX: ffffffffc0476260  RCX: ffff8b617fe94000
>     RDX: ffff8b617fe94000  RSI: ffffffffc0476260  RDI: ffff8b5e45a303a8
>     RBP: ffffffff912b7d30   R8: ffff8b5e45a303b8   R9: ffff8b618dae5900
>     R10: ffff8b617fe94000  R11: 0000000000000001  R12: 00000000ffffffff
>     R13: 0000000000000001  R14: ffff8b617f46ee00  R15: ffff8b60e9a56380
>     ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
>  #8 [ffff9ddf82467e30] mutex_lock at ffffffff90d4a5ce
>  #9 [ffff9ddf82467e50] sysfs_kf_seq_show at ffffffff907b0abb
> 
> Fixed by the checking opts for NULL.
> 
> Fixes: 09fbed636382 (nvme: export fast_io_fail_tmo to sysfs)
> Signed-off-by: Gopal Tiwari <gtiwari at redhat.com>

Do the other functions like nvme_ctrl_loss_tmo_*(),
nvme_sysfs_show_address(), ... not also need this treatment?