Commit 229394e8 authored by Rabin Vincent's avatar Rabin Vincent Committed by David S. Miller

net: bpf: reject invalid shifts

On ARM64, a BUG() is triggered in the eBPF JIT if a filter with a
constant shift that can't be encoded in the immediate field of the
UBFM/SBFM instructions is passed to the JIT.  Since these shifts
amounts, which are negative or >= regsize, are invalid, reject them in
the eBPF verifier and the classic BPF filter checker, for all
architectures.
Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7aaed57c
......@@ -1121,6 +1121,16 @@ static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn)
return -EINVAL;
}
if ((opcode == BPF_LSH || opcode == BPF_RSH ||
opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
if (insn->imm < 0 || insn->imm >= size) {
verbose("invalid shift %d\n", insn->imm);
return -EINVAL;
}
}
/* pattern match 'bpf_add Rx, imm' instruction */
if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
regs[insn->dst_reg].type == FRAME_PTR &&
......
......@@ -785,6 +785,11 @@ static int bpf_check_classic(const struct sock_filter *filter,
if (ftest->k == 0)
return -EINVAL;
break;
case BPF_ALU | BPF_LSH | BPF_K:
case BPF_ALU | BPF_RSH | BPF_K:
if (ftest->k >= 32)
return -EINVAL;
break;
case BPF_LD | BPF_MEM:
case BPF_LDX | BPF_MEM:
case BPF_ST:
......
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