CVE-2022-50628

In the Linux kernel, the following vulnerability has been resolved:

drm/gud: Fix UBSAN warning

UBSAN complains about invalid value for bool:

[ 101.165172] [drm] Initialized gud 1.0.0 20200422 for 2-3.2:1.0 on minor 1 [ 101.213360] gud 2-3.2:1.0: [drm] fb1: guddrmfb frame buffer device [ 101.213426] usbcore: registered new interface driver gud [ 101.989431] ================================================================================ [ 101.989441] UBSAN: invalid-load in linux/include/linux/iosys-map.h:253:9 [ 101.989447] load of value 121 is not a valid value for type 'Bool' [ 101.989451] CPU: 1 PID: 455 Comm: kworker/1:6 Not tainted 5.18.0-rc5-gud-5.18-rc5 #3 [ 101.989456] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991, BIOS L71 Ver. 01.44 04/12/2018 [ 101.989459] Workqueue: eventslong gudflushwork [gud] [ 101.989471] Call Trace: [ 101.989474] <TASK> [ 101.989479] dumpstacklvl+0x49/0x5f [ 101.989488] dumpstack+0x10/0x12 [ 101.989493] ubsanepilogue+0x9/0x3b [ 101.989498] _ubsanhandleloadinvalidvalue.cold+0x44/0x49 [ 101.989504] dmabufvmap.cold+0x38/0x3d [ 101.989511] ? findbusiestgroup+0x48/0x300 [ 101.989520] drmgemshmemvmap+0x76/0x1b0 [drmshmemhelper] [ 101.989528] drmgemshmemobjectvmap+0x9/0xb [drmshmemhelper] [ 101.989535] drmgemvmap+0x26/0x60 [drm] [ 101.989594] drmgemfbvmap+0x47/0x150 [drmkmshelper] [ 101.989630] gudprepflush+0xc1/0x710 [gud] [ 101.989639] ? _rawspinlock+0x17/0x40 [ 101.989648] gudflushwork+0x1e0/0x430 [gud] [ 101.989653] ? _switchto+0x11d/0x470 [ 101.989664] processonework+0x21f/0x3f0 [ 101.989673] workerthread+0x200/0x3e0 [ 101.989679] ? rescuerthread+0x390/0x390 [ 101.989684] kthread+0xfd/0x130 [ 101.989690] ? kthreadcompleteandexit+0x20/0x20 [ 101.989696] retfromfork+0x22/0x30 [ 101.989706] </TASK> [ 101.989708] ================================================================================

The source of this warning is in iosysmapclear() called from dmabufvmap(). It conditionally sets values based on map->isiomem. The iosysmap variables are allocated uninitialized on the stack leading to ->is_iomem having all kinds of values and not only 0/1.

Fix this by zeroing the iosys_map variables.