Description
In the Linux kernel, the following vulnerability has been resolved: perf/core: Prevent VMA split of buffer mappings The perf mmap code is careful about mmap()'ing the user page with the ringbuffer and additionally the auxiliary buffer, when the event supports it. Once the first mapping is established, subsequent mapping have to use the same offset and the same size in both cases. The reference counting for the ringbuffer and the auxiliary buffer depends on this being correct. Though perf does not prevent that a related mapping is split via mmap(2), munmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls, which take reference counts, but then the subsequent perf_mmap_close() calls are not longer fulfilling the offset and size checks. This leads to reference count leaks. As perf already has the requirement for subsequent mappings to match the initial mapping, the obvious consequence is that VMA splits, caused by resizing of a mapping or partial unmapping, have to be prevented. Implement the vm_operations_struct::may_split() callback and return unconditionally -EINVAL. That ensures that the mapping offsets and sizes cannot be changed after the fact. Remapping to a different fixed address with the same size is still possible as it takes the references for the new mapping and drops those of the old mapping.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
45bfb2e50471abbbfd83d40d28c986078b0d24ff to < e4346ffec2c44d6b0be834d59b20632b5bb5729eaffected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < d52451a9210f2e5a079ba052918c93563518a9ffaffected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < 3bd518cc7ea61076bcd725e36ff0e690754977c0affected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < 7b84cb58d1f0aa07656802eae24689566e5f5b1baffected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < 6757a31a8e295ae4f01717a954afda173f25a121affected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < e529888b7e8092912dd8789bdfc76685ccd2ff5faffected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < ff668930871e0198c7f4e325058b8b7c286787bdaffected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < 65311aad4c808bedad0c05d9bb8b06c47dae73ebaffected45bfb2e50471abbbfd83d40d28c986078b0d24ff to < b024d7b56c77191cde544f838debb7f8451cd0d6affected
Linux Linux
Default version status: affected
4.1affected0 to < 4.1unaffected5.4.297 to ≤ 5.4.*unaffected5.10.241 to ≤ 5.10.*unaffected5.15.190 to ≤ 5.15.*unaffected6.1.148 to ≤ 6.1.*unaffected6.6.102 to ≤ 6.6.*unaffected6.12.42 to ≤ 6.12.*unaffected6.15.10 to ≤ 6.15.*unaffected6.16.1 to ≤ 6.16.*unaffected6.17 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/e4346ffec2c44d6b0be834d59b20632b5bb5729e ↗
- https://git.kernel.org/stable/c/d52451a9210f2e5a079ba052918c93563518a9ff ↗
- https://git.kernel.org/stable/c/3bd518cc7ea61076bcd725e36ff0e690754977c0 ↗
- https://git.kernel.org/stable/c/7b84cb58d1f0aa07656802eae24689566e5f5b1b ↗
- https://git.kernel.org/stable/c/6757a31a8e295ae4f01717a954afda173f25a121 ↗
- https://git.kernel.org/stable/c/e529888b7e8092912dd8789bdfc76685ccd2ff5f ↗
- https://git.kernel.org/stable/c/ff668930871e0198c7f4e325058b8b7c286787bd ↗
- https://git.kernel.org/stable/c/65311aad4c808bedad0c05d9bb8b06c47dae73eb ↗
- https://git.kernel.org/stable/c/b024d7b56c77191cde544f838debb7f8451cd0d6 ↗
- https://www.zerodayinitiative.com/advisories/ZDI-25-873/ ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html ↗