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authorRabin Vincent <rabin@rab.in>2016-01-12 20:17:08 +0100
committerDavid S. Miller <davem@davemloft.net>2016-01-12 15:55:39 -0500
commit06928b3870d213cb42b00e2949419f2d44b9d45f (patch)
treed1427c587b190b02f7d2e5b842c1804f38386128
parent03d84a5f83a67e692af00a3d3901e7820e3e84d5 (diff)
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: Rabin Vincent <rabin@rab.in> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--kernel/bpf/verifier.c10
-rw-r--r--net/core/filter.c5
2 files changed, 15 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a7945d10b378..d1d3e8f57de9 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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 &&
diff --git a/net/core/filter.c b/net/core/filter.c
index 672eefbfbe99..37157c4c1a78 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -777,6 +777,11 @@ 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: