CVE-2023-52648 in Linux
Summary
by MITRE • 05/01/2024
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 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: ? __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]
drm_atomic_helper_cleanup_planes+0x9b/0xc0 commit_tail+0xd1/0x130 drm_atomic_helper_commit+0x11a/0x140 drm_atomic_commit+0x97/0xd0 ? __pfx___drm_printfn_info+0x10/0x10 drm_atomic_helper_update_plane+0xf5/0x160 drm_mode_cursor_universal+0x10e/0x270 drm_mode_cursor_common+0x102/0x230 ? __pfx_drm_mode_cursor2_ioctl+0x10/0x10 drm_ioctl_kernel+0xb2/0x110 drm_ioctl+0x26d/0x4b0 ? __pfx_drm_mode_cursor2_ioctl+0x10/0x10 ? __pfx_drm_ioctl+0x10/0x10 vmw_generic_ioctl+0xa4/0x110 [vmwgfx]
__x64_sys_ioctl+0x94/0xd0 do_syscall_64+0x61/0xe0 ? __x64_sys_ioctl+0xaf/0xd0 ? syscall_exit_to_user_mode+0x2b/0x40 ? do_syscall_64+0x70/0xe0 ? __x64_sys_ioctl+0xaf/0xd0 ? syscall_exit_to_user_mode+0x2b/0x40 ? do_syscall_64+0x70/0xe0 ? exc_page_fault+0x7f/0x180 entry_SYSCALL_64_after_hwframe+0x6e/0x76 RIP: 0033:0x7f1e93f279ed Code: 04 25 28 00 00 00 48 89 45 c8 31 c0 48 8d 45 10 c7 45 b0 10 00 00 00 48 89 45 b8 48 8d 45 d0 48 89 45 c0 b8 10 00 00 00 0f 05 c2 3d 00 f0 ff f> RSP: 002b:00007ffca0faf600 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 000055db876ed2c0 RCX: 00007f1e93f279ed RDX: 00007ffca0faf6c0 RSI: 00000000c02464bb RDI: 0000000000000015 RBP: 00007ffca0faf650 R08: 000055db87184010 R09: 0000000000000007 R10: 000055db886471a0 R11: 0000000000000246 R12: 00007ffca0faf6c0 R13: 00000000c02464bb R14: 0000000000000015 R15: 00007ffca0faf790 Modules linked in: snd_seq_dummy snd_hrtimer nf_conntrack_netbios_ns nf_conntrack_broadcast nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_ine> CR2: 0000000000000028 ---[ end trace 0000000000000000 ]---
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 8b 78 28 e8 e3 f> RSP: 0018:ffffb6b98216fa80 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff969d84cdcb00 RCX: 0000000000000027 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff969e75f21600 RBP: ffff969d4143 ---truncated---
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Analysis
by VulDB Data Team • 01/26/2026
The vulnerability identified as CVE-2023-52648 resides within the Linux kernel's vmwgfx driver, specifically affecting the DRM (Direct Rendering Manager) subsystem used for graphics hardware acceleration. This issue manifests as a null pointer dereference during cleanup operations when handling plane state transitions, particularly impacting cursor plane management. The flaw occurs when switching to a new plane state, where the driver fails to properly reset a surface mapping flag after unreferencing surfaces, leading to incorrect state reporting and subsequent system crashes.
The technical root cause of this vulnerability stems from improper state management within the vmwgfx driver's cursor plane handling code. During development of mobile cursor functionality, surfaces began to be cached for performance reasons, but the tracking variable indicating whether a surface is currently mapped was not being reset when surfaces were unreferenced. This results in a stale state condition where the system believes a surface is still mapped even when no actual surface exists, creating a scenario where cleanup functions attempt to access freed memory locations. The issue is particularly evident in KDE KWin 6.0 running under Wayland, where cursor operations trigger the problematic code path.
The operational impact of this vulnerability is significant, as it leads to kernel oops and system crashes that can result in complete system instability. The crash occurs during the cleanup of cursor plane framebuffer operations, specifically in the vmw_du_cursor_plane_cleanup_fb function, where the driver attempts to access a null pointer. The stack trace reveals the execution path leads through drm_atomic_helper_cleanup_planes, commit_tail, and drm_atomic_helper_commit functions before reaching the fatal memory access. This type of vulnerability can be exploited to cause denial of service attacks or potentially enable privilege escalation depending on the execution context, as it represents a classic null pointer dereference that can be leveraged for system instability.
Mitigation strategies for this vulnerability involve applying the kernel patch that resets the surface mapped flag when unreferencing plane state surfaces, effectively correcting the state tracking inconsistency. Organizations should prioritize updating their Linux kernel installations to versions containing the fix, particularly those running VMware virtualized environments with KWin 6.0 or similar Wayland compositors. The fix addresses the underlying CWE-476 Null Pointer Dereference issue by ensuring proper state management and preventing access to invalid memory references. Security teams should monitor for similar state management issues in graphics drivers and consider implementing additional runtime protections such as kernel address space layout randomization and stack canaries to reduce the exploitability of such vulnerabilities. The ATT&CK framework categorizes this vulnerability under T1499.004 (Virtualization/Sandbox Evasion) and T1547.001 (Registry Run Keys/Startup Folder) as potential attack vectors when exploited in virtualized environments, though the primary impact remains system stability and availability rather than direct privilege escalation.