CVE-2022-50884 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
drm: Prevent drm_copy_field() to attempt copying a NULL pointer
There are some struct drm_driver fields that are required by drivers since drm_copy_field() attempts to copy them to user-space via DRM_IOCTL_VERSION.
But it can be possible that a driver has a bug and did not set some of the fields, which leads to drm_copy_field() attempting to copy a NULL pointer:
[ +10.395966] Unable to handle kernel access to user memory outside uaccess routines at virtual address 0000000000000000
[ +0.010955] Mem abort info:
[ +0.002835] ESR = 0x0000000096000004
[ +0.003872] EC = 0x25: DABT (current EL), IL = 32 bits
[ +0.005395] SET = 0, FnV = 0
[ +0.003113] EA = 0, S1PTW = 0
[ +0.003182] FSC = 0x04: level 0 translation fault
[ +0.004964] Data abort info:
[ +0.002919] ISV = 0, ISS = 0x00000004
[ +0.003886] CM = 0, WnR = 0
[ +0.003040] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000115dad000
[ +0.006536] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
[ +0.006925] Internal error: Oops: 96000004 [#1] SMP
... [ +0.011113] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ +0.007061] pc : __pi_strlen+0x14/0x150
[ +0.003895] lr : drm_copy_field+0x30/0x1a4
[ +0.004156] sp : ffff8000094b3a50
[ +0.003355] x29: ffff8000094b3a50 x28: ffff8000094b3b70 x27: 0000000000000040
[ +0.007242] x26: ffff443743c2ba00 x25: 0000000000000000 x24: 0000000000000040
[ +0.007243] x23: ffff443743c2ba00 x22: ffff8000094b3b70 x21: 0000000000000000
[ +0.007241] x20: 0000000000000000 x19: ffff8000094b3b90 x18: 0000000000000000
[ +0.007241] x17: 0000000000000000 x16: 0000000000000000 x15: 0000aaab14b9af40
[ +0.007241] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
[ +0.007239] x11: 0000000000000000 x10: 0000000000000000 x9 : ffffa524ad67d4d8
[ +0.007242] x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : 6c6e6263606e7141
[ +0.007239] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[ +0.007241] x2 : 0000000000000000 x1 : ffff8000094b3b90 x0 : 0000000000000000
[ +0.007240] Call trace:
[ +0.002475] __pi_strlen+0x14/0x150
[ +0.003537] drm_version+0x84/0xac
[ +0.003448] drm_ioctl_kernel+0xa8/0x16c
[ +0.003975] drm_ioctl+0x270/0x580
[ +0.003448] __arm64_sys_ioctl+0xb8/0xfc
[ +0.003978] invoke_syscall+0x78/0x100
[ +0.003799] el0_svc_common.constprop.0+0x4c/0xf4
[ +0.004767] do_el0_svc+0x38/0x4c
[ +0.003357] el0_svc+0x34/0x100
[ +0.003185] el0t_64_sync_handler+0x11c/0x150
[ +0.004418] el0t_64_sync+0x190/0x194
[ +0.003716] Code: 92402c04 b200c3e8 f13fc09f 5400088c (a9400c02)
[ +0.006180] ---[ end trace 0000000000000000 ]---
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability described in CVE-2022-50884 resides within the Linux kernel's direct rendering manager subsystem, specifically in the drm_copy_field() function that handles copying driver information to user space during DRM_IOCTL_VERSION operations. This flaw represents a classic null pointer dereference issue that can lead to system crashes and potential privilege escalation. The vulnerability occurs when certain struct drm_driver fields required for proper operation are not correctly initialized by device drivers, causing the kernel to attempt copying from a NULL pointer address. This situation manifests as an invalid memory access exception that triggers a kernel oops and system panic, fundamentally compromising system stability and security.
The technical implementation of this vulnerability stems from insufficient input validation within the drm_copy_field() function which does not check whether the source pointer is NULL before attempting to copy data to user space. When a graphics driver fails to properly initialize required fields in the drm_driver structure, the subsequent call to drm_copy_field() attempts to access memory at address zero, triggering a data abort exception. The kernel's memory management subsystem detects this invalid access and generates a detailed error trace showing the fault occurring in __pi_strlen() function which is called by drm_copy_field(). This pattern of execution demonstrates how a simple uninitialized pointer can cascade into a complete system failure, with the call trace revealing the path from user-space ioctl calls through drm_ioctl_kernel to the final kernel oops in the memory access handler.
From an operational security perspective, this vulnerability presents a significant risk to systems running graphics-intensive applications or those utilizing DRM subsystems for display management. The impact extends beyond simple system crashes to potentially enable attackers to exploit the kernel memory corruption for privilege escalation or denial of service attacks. The vulnerability aligns with CWE-476 which describes NULL Pointer Dereference, and demonstrates characteristics that could map to ATT&CK techniques such as privilege escalation through kernel exploits and system compromise via kernel memory corruption. Systems using graphics drivers that do not properly initialize all required drm_driver fields are at risk, particularly those running in enterprise environments where graphics processing is critical for applications like video rendering, gaming, or virtual desktop infrastructure.
The mitigation strategy for this vulnerability involves ensuring that all drm_driver structures are properly initialized before use, with specific attention to required fields that may be accessed by drm_copy_field(). Kernel updates addressing this vulnerability should include proper NULL pointer checks in the drm_copy_field() function to prevent invalid memory access attempts. Additionally, device driver developers must ensure complete initialization of drm_driver structures, particularly fields related to version information and driver capabilities. System administrators should prioritize applying kernel patches that contain the fix for this vulnerability, which typically involves adding validation checks in the drm subsystem to verify pointer validity before memory operations. The fix should also include enhanced error handling that gracefully manages uninitialized driver structures rather than allowing kernel crashes, thereby preventing potential exploitation by malicious actors seeking to leverage this memory corruption for unauthorized system access.