Re: [PATCH] scsi: sd: fix crashes in sd_resume_runtime

Bart Van Assche
2021-10-15T21:14:42Z

On 10/15/21 13:11, miles.chen@mediatek.com wrote:
> I hit this in v5.15-rc1 merge, I can still reproduce this with v5.15-rc5.
> I found two ways to avoid the crash:
> 1) revert commit ed4246d37f3b ("scsi: sd: REQUEST SENSE for
> BLIST_IGN_MEDIA_CHANGE devices in runtime_resume()") works for me.
> 2) adding the NULL point check in this patch.
>
>>From the backtrace, dev_set_drvdata() is called after sd_resume_runtime()
> is called.
>
> sd_probe()
> {
> scsi_autopm_get_device()
> pm_runtime_get_sync()
> __pm_runtime_resume()
> rpm_resume()
> ...
> sd_resume_runtime() // crash here
>
> dev_set_drvdata(dev, sdkp); // sdkp is set later
> }
>
> [ 4.861395][ T151] sd_resume_runtime+0x20/0x14c
> [ 4.862025][ T151] scsi_runtime_resume+0x84/0xe4
> [ 4.862667][ T151] __rpm_callback+0x1f4/0x8cc
> [ 4.863275][ T151] rpm_resume+0x7e8/0xaa4
> [ 4.863836][ T151] __pm_runtime_resume+0xa0/0x110
> [ 4.864489][ T151] sd_probe+0x30/0x428
> [ 4.865016][ T151] really_probe+0x14c/0x500

Thanks for the clarification. Given this clarification I'm fine with
your patch.

Bart.