Bug 2400732 (CVE-2021-4460)

Summary: CVE-2021-4460 kernel: drm/amdkfd: Fix UBSAN shift-out-of-bounds warning
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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OS: Linux   
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Description OSIDB Bzimport 2025-10-01 12:04:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amdkfd: Fix UBSAN shift-out-of-bounds warning

If get_num_sdma_queues or get_num_xgmi_sdma_queues is 0, we end up
doing a shift operation where the number of bits shifted equals
number of bits in the operand. This behaviour is undefined.

Set num_sdma_queues or num_xgmi_sdma_queues to ULLONG_MAX, if the
count is >= number of bits in the operand.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1472
Comment 1 Jon Moroney 2025-10-01 22:05:18 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025100114-CVE-2021-4460-aa71@gregkh/T