CVE-2024-46709

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

drm/vmwgfx: Fix prime with external buffers

Make sure that for external buffers mapping goes through the dma_buf interface instead of trying to access pages directly.

External buffers might not provide direct access to readable/writable pages so to make sure the bo's created from external dma_bufs can be read dma_buf interface has to be used.

Fixes crashes in IGT's kms_prime with vgem. Regular desktop usage won't trigger this due to the fact that virtual machines will not have multiple GPUs but it enables better test coverage in IGT.

A low impact flaw was found in the Linux kernel's vmwgfx (VMware graphics) driver, affecting the kernel and kernel-rt packages in Red Hat Enterprise Linux 9. When a graphics buffer object is created from an external dma_buf (PRIME import), the driver could attempt to access the buffer's pages directly instead of going through the dma_buf mapping interface. Because external buffers may not provide directly readable or writable pages, this incorrect mapping can crash the kernel. A local user with the high privileges needed to set up PRIME buffer sharing with external buffers could therefore cause a denial of service (kernel crash); there is no impact on confidentiality or integrity. Triggering this issue effectively requires multiple GPUs in the guest, and regular desktop usage in virtual machines does not exercise this path (the crashes were observed in the IGT kms_prime tests using vgem). For these reasons Red Hat rates the flaw Low severity (CVSS 4.4, AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H), a meaningful difference from the upstream CVE record's score of 7.8, which assumes full confidentiality, integrity, and availability impact. In Red Hat Enterprise Linux 9 the fix is currently deferred, given the low severity and the fact that regular desktop usage does not trigger the flaw; the residual risk is that a privileged local user in the unusual multi-GPU PRIME configuration described above could still trigger a kernel crash. Fedora is also affected, with a fix being pursued through the community kernel process. Red Hat Enterprise Linux 8 and Red Hat's hosted OpenShift offerings are not affected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.