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authorWilliam Tu <u9012063@gmail.com>2017-02-04 08:37:29 -0800
committerDavid S. Miller <davem@davemloft.net>2017-02-06 22:50:04 -0500
commit63dfef75ed75364901d7caa52c6420cec3e73519 (patch)
tree8c3065d18a1b80da112ec1ee9a1074240cd100ca /kernel
parent29200c199cc9bde59033ab30fcc40b6c8ae630b0 (diff)
downloadlinux-63dfef75ed75364901d7caa52c6420cec3e73519.tar.bz2
bpf: enable verifier to add 0 to packet ptr
The patch fixes the case when adding a zero value to the packet pointer. The zero value could come from src_reg equals type BPF_K or CONST_IMM. The patch fixes both, otherwise the verifer reports the following error: [...] R0=imm0,min_value=0,max_value=0 R1=pkt(id=0,off=0,r=4) R2=pkt_end R3=fp-12 R4=imm4,min_value=4,max_value=4 R5=pkt(id=0,off=4,r=4) 269: (bf) r2 = r0 // r2 becomes imm0 270: (77) r2 >>= 3 271: (bf) r4 = r1 // r4 becomes pkt ptr 272: (0f) r4 += r2 // r4 += 0 addition of negative constant to packet pointer is not allowed Signed-off-by: William Tu <u9012063@gmail.com> Signed-off-by: Mihai Budiu <mbudiu@vmware.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index fb3513b35c0b..1a754e5d2695 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1397,7 +1397,7 @@ static int check_packet_ptr_add(struct bpf_verifier_env *env,
imm = insn->imm;
add_imm:
- if (imm <= 0) {
+ if (imm < 0) {
verbose("addition of negative constant to packet pointer is not allowed\n");
return -EACCES;
}