On Monday, 8 June 2026 18:19:04 CEST Maxime Ripard wrote: > On Mon, Jun 08, 2026 at 05:41:11PM +0200, Romain Gantois wrote: > > Hi Maxime, > > ... > > > You're only partially fixing the issue. You also need to protect any > > > device resource (register mapping, clocks, etc) are no longer accessed > > > after the device has been removed, and this is typically done using > > > drm_dev_enter/exit. > > > > Sorry there's something which I don't quite understand: is this a new > > issue > > which is specifically introduced by my changes in this series, or a > > different issue in this driver which isn't handled by my series? > > A bit of both I guess ? :) > > My point was that while your commit log claims you avoid use-after-free, > and your patch definitely avoids some, you can still trivially trigger > some. > > Whether you want to fix them all at once or prefer to defer it to a > later point in time is equally fine by me, but you need to be aware that > it's not done, and you probably want to have it in the commit log > somewhere too? >
Ah ok, I didn't mean to claim that I was fixing any potential UAF in the driver. But if there's another one then I'm definitely interested in fixing it as well :). > > IIUC all I'm doing here is just letting the drmm code handle cleaning up > > the plane, crtc, etc. objects instead of doing it "by hand" with > > devm_kzalloc. Why does this make it necessary to add additional > > protection of driver resources? > > It's not necessary, but it's also kind of the same issue. The reason we > need to have drmm over devm is that the driver stays around longer than > its device, so devm-allocated memory would have been freed. > > But that's also the case for *any* devm resource, or more generally any > resource linked to that device, so register mappings, clocks, > interrupts, etc. > > So yeah, it's a different symptom of the same underlying cause. Okay, I'll assess the issue and probably make another patch in the same series to fix that. Thanks, -- Romain Gantois, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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