In the Linux kernel, the following vulnerability has been resolved: bpf: Reject arena frees below the arena base bpf_arena_free_pages() accepts scalar arena addresses. The runtime masks the address to the low 32 bits and reconstructs a full user address from the arena base before returning the range to the arena free tree. When the scalar value is below the low 32 bits of the arena base, full_uaddr falls below user_vm_start. The existing upper-end clipping then turns this into an out-of-range free-tree offset. A later allocation can reuse that offset and return an address below the arena mapping. Reject such frees before computing the clipped range.
https://git.kernel.org/stable/c/b5a71cb2db6d84ac0042549dcec266b18429d41e
https://git.kernel.org/stable/c/a968dffa5ab3c74d2ebb3a6233bf8b843f0bfc20
https://git.kernel.org/stable/c/90453eaf8f14e7be0ab03983f2a93aeb6b990a58
https://git.kernel.org/stable/c/8a08635656037aee9c12231ed384449c4ffb1a93