CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's handling of scalar registers during sign-extending operations in BPF (Berkeley Packet Filter) programs. This flaw can lead to incorrect assumptions about register values, potentially resulting in out-of-bounds memory access, which could be exploited by attackers to execute arbitrary code or cause system instability. Organizations using Linux systems that implement BPF should prioritize addressing this issue to mitigate potential security risks.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Drop scalar id on sign-extending narrowing stack fills When a spilled scalar is filled back with a sign-extending narrowing load (BPF_MEMSX), check_stack_read_fixed_off() copies the spilled register including its scalar id, but coerce_reg_to_size_sx() then sign-extends the filled register's value. If the same slot is also filled with a plain zero-extending load (BPF_MEM), both destination registers share the id yet hold different values. A later 'if <zext-reg> == const' then refines the sign-extended register through sync_linked_regs() to a value it does not have at runtime (e.g. the verifier believes 0x80000000 while the register is 0xffffffff80000000), which can be turned into an out-of-bounds access. Drop the shared scalar id at the sign-extension site in check_mem_access() when sign extension actually changes the value, mirroring the BPF_MOVSX handling in check_alu_op() (no_sext = reg_umax < 2^(size*8-1)).