Executive brief
A memory management issue was identified in the Linux kernel's Andrew File System (AFS) component. This flaw could lead to a resource leak (reference count leak) when the system fails to allocate memory or merge memory regions during file mapping operations. While primarily a technical stability issue, such leaks can eventually lead to system instability or resource exhaustion.
Technical details
A vulnerability was identified in the Linux kernel's AFS filesystem implementation where the use of the .mmap_prepare() callback caused reference count leaks. The .mmap invocation establishes a refcount, but .mmap_prepare is called at a point in the memory management lifecycle where subsequent merge or allocation failures can occur. If such a failure happens after the refcount is incremented but before the mapping is finalized, the increment is never reverted. The fix involves reverting the AFS implementation from .mmap_prepare() back to the standard .mmap() callback to ensure proper resource tracking.
Affected products
- Linux Linux Kernel All versions prior to the fix in May 2026
Timeline
- 2026-03-20: other: Patch authored
- 2026-05-27: disclosed: CVE published