CVE-2026-53329: Linux Kernel Buffer Overflow Vulnerability

CVE-2026-53329 Overview

CVE-2026-53329 is an integer overflow vulnerability in the Linux kernel's AMD Display driver (drm/amd/display). The flaw resides in dal_vector_reserve(), which computes an allocation size as capacity * vector->struct_size using uint32_t arithmetic. The multiplication can silently wrap on overflow, causing krealloc() to return a buffer smaller than expected. Subsequent vector appends then write past the end of the allocation, producing a heap overflow in kernel memory. Upstream maintainers resolved the issue by switching to krealloc_array(), which performs an internal overflow check and returns NULL on wrap.

Critical Impact
An integer overflow in the AMD display kernel driver leads to an undersized heap allocation and subsequent kernel heap overflow, which may enable memory corruption or local privilege escalation on affected Linux systems.

Affected Products

Linux kernel builds that include the AMD Display (drm/amd/display) driver prior to the fix cherry-picked from commit 37668568641ccc4cc1dbca4923d0a16609dd5707
Stable Linux kernel branches referenced by the associated git.kernel.org fix commits
Distributions shipping vulnerable versions of the amdgpu display kernel component

Discovery Timeline

2026-07-01 - CVE-2026-53329 published to NVD
2026-07-01 - Last updated in NVD database

Technical Details for CVE-2026-53329

Vulnerability Analysis

The vulnerability sits in the display abstraction layer (DAL) helper dal_vector_reserve(), used to grow dynamic vector containers in the AMD display driver. The function multiplies the requested capacity by the element size vector->struct_size to compute the total allocation. Because both operands are 32-bit unsigned integers, a sufficiently large capacity or struct_size causes the product to wrap around modulo 2^32. The wrapped value is then passed to krealloc(), which happily returns a buffer far smaller than the caller expects. Later code paths that append elements to the vector operate on the original, non-wrapped capacity assumption and write beyond the allocation, corrupting adjacent kernel heap memory.

Root Cause

The root cause is unchecked 32-bit multiplication in an allocation size calculation, an instance of numeric overflow leading to a buffer size mismatch [CWE-190, CWE-122]. The corrective patch replaces the raw krealloc() call with krealloc_array(p, new_n, new_size, flags), which uses compiler-assisted overflow detection and fails safely by returning NULL when the multiplication would wrap.

Attack Vector

Exploitation requires the ability to trigger allocation paths inside the AMD display driver with attacker-influenced sizing. Reaching dal_vector_reserve() with a controlled capacity typically requires local access to the graphics stack or the ability to interact with the amdgpu driver via ioctl, sysfs, or DRM interfaces. A successful exploit yields kernel-mode heap corruption, which can be developed into privilege escalation or a denial of service on affected systems.

No verified public exploit code is available for CVE-2026-53329. Refer to the upstream fix commits on git.kernel.org for the exact source-level change.

Detection Methods for CVE-2026-53329

Indicators of Compromise

Kernel oops or panic messages referencing dal_vector_reserve, dal_vector_append, or nearby symbols in the AMD display driver stack
KASAN or SLUB debug reports flagging out-of-bounds writes in allocations originating from drm/amd/display code paths
Unexpected amdgpu driver crashes on systems where untrusted local users can interact with the graphics stack

Detection Strategies

Inventory running kernel versions across the fleet and compare against the fixed stable branches listed in the upstream commit references
Enable KASAN in test or canary kernels to surface heap out-of-bounds writes triggered by graphics workloads
Correlate userland crashes in graphical sessions with kernel-side backtraces mentioning DAL vector helpers

Monitoring Recommendations

Forward dmesg and journald kernel logs to a centralized logging platform and alert on amdgpu or drm fault signatures
Track process activity that interacts with DRM device nodes (/dev/dri/*) from non-graphical or low-privilege contexts
Monitor sudden reboots, GPU resets, or driver reinitializations that could indicate exploitation attempts

How to Mitigate CVE-2026-53329

Immediate Actions Required

Apply the stable-tree kernel updates containing the krealloc_array() fix from the referenced upstream commits
Reboot affected hosts after patching to ensure the vulnerable module is unloaded
On multi-user systems, restrict access to DRM device nodes to trusted users until the patch is deployed

Patch Information

The fix replaces krealloc() with krealloc_array() inside dal_vector_reserve() so that the allocation size calculation is checked for overflow. The change was cherry-picked from mainline commit 37668568641ccc4cc1dbca4923d0a16609dd5707 into multiple stable branches. Reference commits: 201151e1, 31180638, a914aa80, b15825de, da48bc44, de988c7a, and e0968928.

Workarounds

Where patching is not immediately feasible, restrict /dev/dri/* access via group membership and udev rules to reduce local exposure
Avoid loading the amdgpu display driver on systems that do not require AMD graphics acceleration
Enforce least-privilege on interactive systems so that untrusted users cannot open DRM interfaces

bash

# Verify the running kernel version and reload after patch installation
uname -r
sudo apt update && sudo apt install --only-upgrade linux-image-$(uname -r | sed 's/-generic//')-generic
sudo systemctl reboot