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In the Linux kernel, a vulnerability has been identified in the drm/msm (Mobile Station Module) graphics driver, specifically within the `msm_iommu.c` file. The core of this issue lies in the improper handling of return values from the `iommu_map_sgtable()` function. A prior commit, d “iommu: return full error code from iommu_map_sg_atomic“, altered the function’s signature to return an `ssize_t` type, which can be a negative value to indicate an error, rather than a `size_t` which would return zero on failure. The vulnerability arises because the `drm/msm` driver did not update its logic to accommodate this change. Consequently, the driver continued to incorrectly interpret the return value, failing to detect error conditions properly. This mismatch means that when an IOMMU mapping operation fails, the driver would not propagate the error code up the call stack; instead, it would trigger a kernel WARN message. This improper error handling can obscure actual failure conditions, potentially leading to memory management failures, system instability, or in worst-case scenarios, privilege escalation. The vulnerability affects systems using the msm driver, which is commonly found in devices utilizing Qualcomm’s Adreno GPU for display operations. The fix involves properly storing the return value in an `ssize_t` variable and returning it on error, rather than issuing a warning. This change aligns with defensive programming practices, ensuring that errors are correctly propagated and not masked. The issue was introduced in kernel version 5.15 with commit `ad8f36e4b6b1c826a0daa5fda2c5839205b5aa8b` and is classified under CWE-252 (Unchecked Return Value).
DailyCVE Form:
Platform: Linux Kernel
Version: 5.15 – 7.0.10
Vulnerability: Unchecked Return Value
Severity: Medium
date: 2026-07-19
Prediction: 2026-07-20
What Undercode Say:
Check if the system is vulnerable by verifying the kernel version uname -r Check the introduced commit in the kernel source git log --oneline | grep ad8f36e4b6b1c826a0daa5fda2c5839205b5aa8b Check for the fixed commit in the current kernel source git log --oneline | grep 3c2cdb7c07f664b77e2a75b50793b845d5742efa
Exploit: (Educational Purposes!)
// Vulnerable code snippet from drivers/gpu/drm/msm/msm_iommu.c // Prior to the fix, the return value was incorrectly handled size_t ret; ret = iommu_map_sgtable(domain, iova, sgt, prot); if (ret) // This check is flawed as iommu_map_sgtable now returns ssize_t return ret; // Fixed code: Properly store and check the return value ssize_t ret; ret = iommu_map_sgtable(domain, iova, sgt, prot); if (ret < 0) return ret;
Protection:
To protect against this vulnerability, it is imperative to update the Linux kernel to a version that includes the fix. The vulnerability is resolved in the following versions:
– 5.15.209
– 6.1.175
– 6.6.142
– 6.12.92
– 6.18.34
– 7.0.11
– 7.1
Users should apply the latest stable kernel updates from their distribution vendors. For Debian-based systems, the fixed packages are available for bullseye (5.10.223-1), bookworm (6.1.176-1), trixie (6.12.94-1), forky (7.1.3-1), and sid (7.1.4-1).
Impact:
The primary impact of this vulnerability is on system stability and security within graphics processing pipelines. The improper error handling can cause the kernel to issue WARN messages, potentially obscuring critical IOMMU mapping failures. This behavior can lead to subsequent memory management errors, which might be exploited for local privilege escalation (ATT&CK technique T1068). Systems that rely on the msm driver for display operations are particularly at risk, as IOMMU protection is essential for preventing unauthorized memory access. The vulnerability could result in complete system crashes or create opportunities for malicious actors to compromise the system.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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