CVE-2026-43302

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

drm/v3d: Set DMA segment size to avoid debug warnings

When using V3D rendering with CONFIG_DMA_API_DEBUG enabled, the kernel occasionally reports a segment size mismatch. This is because max_seg_size is not set. The kernel defaults to 64K. setting max_seg_size to the maximum will prevent debug_dma_map_sg() from complaining about the over-mapping of the V3D segment length.

DMA-API: v3d 1002000000.v3d: mapping sg segment longer than device claims to support [len=8290304] [max=65536] WARNING: CPU: 0 PID: 493 at kernel/dma/debug.c:1179 debug_dma_map_sg+0x330/0x388 CPU: 0 UID: 0 PID: 493 Comm: Xorg Not tainted 6.12.53-yocto-standard #1 Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT) pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=–) pc : debug_dma_map_sg+0x330/0x388 lr : debug_dma_map_sg+0x330/0x388 sp : ffff8000829a3ac0 x29: ffff8000829a3ac0 x28: 0000000000000001 x27: ffff8000813fe000 x26: ffffc1ffc0000000 x25: ffff00010fdeb760 x24: 0000000000000000 x23: ffff8000816a9bf0 x22: 0000000000000001 x21: 0000000000000002 x20: 0000000000000002 x19: ffff00010185e810 x18: ffffffffffffffff x17: 69766564206e6168 x16: 74207265676e6f6c x15: 20746e656d676573 x14: 20677320676e6970 x13: 5d34303334393134 x12: 0000000000000000 x11: 00000000000000c0 x10: 00000000000009c0 x9 : ffff8000800e0b7c x8 : ffff00010a315ca0 x7 : ffff8000816a5110 x6 : 0000000000000001 x5 : 000000000000002b x4 : 0000000000000002 x3 : 0000000000000008 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff00010a315280 Call trace: debug_dma_map_sg+0x330/0x388 __dma_map_sg_attrs+0xc0/0x278 dma_map_sgtable+0x30/0x58 drm_gem_shmem_get_pages_sgt+0xb4/0x140 v3d_bo_create_finish+0x28/0x130 [v3d] v3d_create_bo_ioctl+0x54/0x180 [v3d] drm_ioctl_kernel+0xc8/0x140 drm_ioctl+0x2d4/0x4d8

Weakness

The product does not correctly calculate the size to be used when allocating a buffer, which could lead to a buffer overflow.

Affected Software

Potential Mitigations

• Understand the programming language’s underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, “not-a-number” calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7]
• Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
• Use libraries or frameworks that make it easier to handle numbers without unexpected consequences, or buffer allocation routines that automatically track buffer size.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
• Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
• D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
• Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
• Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
• For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
• Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment.
• For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].
• Run the code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
• OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
• This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
• Be careful to avoid CWE-243 and other weaknesses related to jails.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/100.html
• https://cwe.mitre.org/data/definitions/47.html

References

• https://git.kernel.org/stable/c/0290934d30abe7c88e18140fd5184c3f386b1e44
• https://git.kernel.org/stable/c/14d0d6c8b4504a60cfeea74775ab2e0164019e65
• https://git.kernel.org/stable/c/225023e3619b81af6d8d0e680503fc2d68633023
• https://git.kernel.org/stable/c/2663ef70c6123b2232190f917275e5c3175f97d0
• https://git.kernel.org/stable/c/9eb018828b1b30dfba689c060735c50fc5b9f704
• https://git.kernel.org/stable/c/cf510785f74e74c54de40a43a955b7f844857487
• https://git.kernel.org/stable/c/db15f469a88d3bbeeaa9f8c9f5e74d856ba5d7d2