A flaw was found in the Linux kernel. This flaw allows a local user to cause a Denial of Service (DoS) by crashing the system. A race condition during memory section deactivation in the memory management subsystem can lead to a null pointer dereference in the pfn_section_valid() function due to a missing pointer validation check.
In the Linux kernel, the following vulnerability has been resolved:
mm: prevent derefencing NULL ptr in pfn_section_valid()
Commit 5ec8e8ea8b77 ("mm/sparsemem: fix race in accessing
memory_section->usage") changed pfn_section_valid() to add a READ_ONCE()
call around "ms->usage" to fix a race with section_deactivate() where
ms->usage can be cleared. The READ_ONCE() call, by itself, is not enough
to prevent NULL pointer dereference. We need to check its value before
dereferencing it.
Comment 1Mauro Matteo Cascella
2024-07-30 10:57:21 UTC
In the Linux kernel, the following vulnerability has been resolved: mm: prevent derefencing NULL ptr in pfn_section_valid() Commit 5ec8e8ea8b77 ("mm/sparsemem: fix race in accessing memory_section->usage") changed pfn_section_valid() to add a READ_ONCE() call around "ms->usage" to fix a race with section_deactivate() where ms->usage can be cleared. The READ_ONCE() call, by itself, is not enough to prevent NULL pointer dereference. We need to check its value before dereferencing it.