Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/sdma4: replace BUG_ON with WARN_ON in fence emission
sdma_v4_0_ring_emit_fence() contains two BUG_ON(addr & 0x3) assertions that verify fence writeback addresses are dword-aligned. These assertions can be reached from unprivileged userspace via crafted DRM_IOCTL_AMDGPU_CS submissions, causing a fatal kernel panic in a scheduler worker thread.
Replace both BUG_ON() calls with WARN_ON() to log the condition without crashing the kernel. A misaligned fence address at this point indicates a driver bug, but crashing the kernel is never the correct response when the assertion is reachable from userspace.
The CS IOCTL path is the correct place to filter invalid submissions; the ring emission callback is too late to do anything about it.
(cherry picked from commit b90250bd933afd1ba94d86d6b13821997b22b18e)
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 4.18.0 (+8 more)
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/sdma4: replace BUG_ON with WARN_ON in fence emission
sdma_v4_0_ring_emit_fence() contains two BUG_ON(addr & 0x3) assertions that verify fence writeback addresses are dword-aligned. These assertions can be reached from unprivileged userspace via crafted DRM_IOCTL_AMDGPU_CS submissions, causing a fatal kernel panic in a scheduler worker thread.
Replace both BUG_ON() calls with WARN_ON() to log the condition without crashing the kernel. A misaligned fence address at this point indicates a driver bug, but crashing the kernel is never the correct response when the assertion is reachable from userspace.
The CS IOCTL path is the correct place to filter invalid submissions; the ring emission callback is too late to do anything about it.
(cherry picked from commit b90250bd933afd1ba94d86d6b13821997b22b18e)