In the Linux kernel, the following vulnerability has been resolved:
drm/vmwgfx: Unmap the surface before resetting it on a plane state
Switch to a new plane state requires unreferencing of all held surfaces. In the work required for mob cursors the mapped surfaces started being cached but the variable indicating whether the surface is currently mapped was not being reset. This leads to crashes as the duplicated state, incorrectly, indicates the that surface is mapped even when no surface is present. That's because after unreferencing the surface it's perfectly possible for the plane to be backed by a bo instead of a surface.
Reset the surface mapped flag when unreferencing the plane state surface to fix null derefs in cleanup. Fixes crashes in KDE KWin 6.0 on Wayland:
Oops: 0000 [#1] PREEMPT SMP PTI CPU: 4 PID: 2533 Comm: kwin_wayland Not tainted 6.7.0-rc3-vmwgfx #2 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 RIP: 0010:vmw_du_cursor_plane_cleanup_fb+0x124/0x140 [vmwgfx] Code: 00 00 00 75 3a 48 83 c4 10 5b 5d c3 cc cc cc cc 48 8b b3 a8 00 00 00 48 c7 c7 99 90 43 c0 e8 93 c5 db ca 48 8b 83 a8 00 00 00 <48> 8b 78 28 e8 e3 f> RSP: 0018:ffffb6b98216fa80 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff969d84cdcb00 RCX: 0000000000000027 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff969e75f21600 RBP: ffff969d4143dc50 R08: 0000000000000000 R09: ffffb6b98216f920 R10: 0000000000000003 R11: ffff969e7feb3b10 R12: 0000000000000000 R13: 0000000000000000 R14: 000000000000027b R15: ffff969d49c9fc00 FS: 00007f1e8f1b4180(0000) GS:ffff969e75f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000028 CR3: 0000000104006004 CR4: 00000000003706f0 Call Trace: <TASK> ? __die+0x23/0x70 ? page_fault_oops+0x171/0x4e0 ? exc_page_fault+0x7f/0x180 ? asm_exc_page_fault+0x26/0x30 ? vmw_du_cursor_plane_cleanup_fb+0x124/0x140 [vmwgfx]...