CVE-2023-52928

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> bpf: Skip invalid kfunc call in backtrack_insn<br /> <br /> The verifier skips invalid kfunc call in check_kfunc_call(), which<br /> would be captured in fixup_kfunc_call() if such insn is not eliminated<br /> by dead code elimination. However, this can lead to the following<br /> warning in backtrack_insn(), also see [1]:<br /> <br /> ------------[ cut here ]------------<br /> verifier backtracking bug<br /> WARNING: CPU: 6 PID: 8646 at kernel/bpf/verifier.c:2756 backtrack_insn<br /> kernel/bpf/verifier.c:2756<br /> __mark_chain_precision kernel/bpf/verifier.c:3065<br /> mark_chain_precision kernel/bpf/verifier.c:3165<br /> adjust_reg_min_max_vals kernel/bpf/verifier.c:10715<br /> check_alu_op kernel/bpf/verifier.c:10928<br /> do_check kernel/bpf/verifier.c:13821 [inline]<br /> do_check_common kernel/bpf/verifier.c:16289<br /> [...]<br /> <br /> So make backtracking conservative with this by returning ENOTSUPP.<br /> <br /> [1] https://lore.kernel.org/bpf/CACkBjsaXNceR8ZjkLG=dT3P=4A8SBsg0Z5h5PWLryF5=ghKq=g@mail.gmail.com/