On Wed, Nov 09, 2022 at 03:03:14PM +0100, Daniel Vetter wrote: > On Tue, Nov 08, 2022 at 07:38:23PM +0100, Stanislaw Gruszka wrote: > > If drm_sysfs_minor_alloc() fail in drm_minor_alloc() we can end up > > freeing invalid minor->kdev pointer and drm_minor_alloc_release() > > will crash like below: > > > > RIP: 0010:kobject_put+0x19/0x1c0 > > RSP: 0018:ffffbc7001637c38 EFLAGS: 00010282 > > RAX: ffffffffa8d6deb0 RBX: 00000000ffffffff RCX: ffff9cb5912d4540 > > RDX: ffffffffa9c45ec5 RSI: ffff9cb5902f2b68 RDI: fffffffffffffff4 > > RBP: fffffffffffffff4 R08: ffffffffa9c40dec R09: 0000000000000008 > > R10: ffffffffaa81f7d2 R11: 00000000aa81f7ca R12: ffff9cb5912d4540 > > R13: ffff9cb5912d4540 R14: dead000000000122 R15: dead000000000100 > > FS: 00007f56b06e6740(0000) GS:ffff9cb728b40000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000030 CR3: 000000011285b004 CR4: 0000000000170ee0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000ffff07f0 DR7: 0000000000000400 > > Call Trace: > > <TASK> > > drm_minor_alloc_release+0x19/0x50 > > drm_managed_release+0xab/0x150 > > drm_dev_init+0x21f/0x2f0 > > __devm_drm_dev_alloc+0x3c/0xa0 > > ivpu_probe+0x59/0x797 [intel_vpu 127058409b05eb2f99dcdecd3330bee28d6b3e76] > > pci_device_probe+0xa4/0x160 > > really_probe+0x164/0x340 > > __driver_probe_device+0x10d/0x190 > > device_driver_attach+0x26/0x50 > > bind_store+0x9f/0x120 > > kernfs_fop_write_iter+0x12d/0x1c0 > > new_sync_write+0x106/0x180 > > vfs_write+0x216/0x2a0 > > ksys_write+0x65/0xe0 > > do_syscall_64+0x35/0x80 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > > > Fix this crash by returning NULL minor->kdev on error. > > > > Fixes: f96306f9892b ("drm: manage drm_minor cleanup with drmm_") > > Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@xxxxxxxxxxxxxxx> > > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> I see this is not yet applied: https://patchwork.freedesktop.org/patch/510798/ Could this be applied? Or should I go with the revert of f96306f9892b ("drm: manage drm_minor cleanup with drmm_") to fix this issue. Regards Stanislaw > On the entire drmm thing, you can avoid these if you do a drmm for every > little thing, that way you never get stuff that might or might not be set > up in the cleanup handler. But for one-off internal things that's a bit > overkill, and C utterly sucks at taking care of the boilerplate. > -Daniel > > > --- > > v2: return minor->kdev NULL pointer instead of checking for IS_ERR in > > drm_minor_alloc_release() > > > > drivers/gpu/drm/drm_drv.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c > > index 8214a0b1ab7f..8d70b634d008 100644 > > --- a/drivers/gpu/drm/drm_drv.c > > +++ b/drivers/gpu/drm/drm_drv.c > > @@ -142,8 +142,11 @@ static int drm_minor_alloc(struct drm_device *dev, unsigned int type) > > return r; > > > > minor->kdev = drm_sysfs_minor_alloc(minor); > > - if (IS_ERR(minor->kdev)) > > - return PTR_ERR(minor->kdev); > > + if (IS_ERR(minor->kdev)) { > > + r = PTR_ERR(minor->kdev); > > + minor->kdev = NULL; > > + return r; > > + } > > > > *drm_minor_get_slot(dev, type) = minor; > > return 0; > > -- > > 2.25.1 > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch