diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2012-03-18 02:40:48 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-04-02 09:53:08 -0700 |
| commit | 8a9ecfa63e8113306420f60832b0b9631e26ec57 (patch) | |
| tree | 5997f9972da777165a246f138551831fbd0905cb | |
| parent | 0cff40794bd89b8218f64f8fe058fbf67835fc2f (diff) | |
net: bpf_jit: fix BPF_S_LDX_B_MSH compilation
[ Upstream commit dc72d99dabb870ca5bd6d9fff674be853bb4a88d ]
Matt Evans spotted that x86 bpf_jit was incorrectly handling negative
constant offsets in BPF_S_LDX_B_MSH instruction.
We need to abort JIT compilation like we do in common_load so that
filter uses the interpreter code and can call __load_pointer()
Reference: http://lists.openwall.net/netdev/2011/07/19/11
Thanks to Indan Zupancic to bring back this issue.
Reported-by: Matt Evans <matt@ozlabs.org>
Reported-by: Indan Zupancic <indan@nul.nu>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 14 |
1 files changed, 5 insertions, 9 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 7c1b765ecc59..5671752f8d9c 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -475,8 +475,10 @@ void bpf_jit_compile(struct sk_filter *fp) case BPF_S_LD_W_ABS: func = sk_load_word; common_load: seen |= SEEN_DATAREF; - if ((int)K < 0) + if ((int)K < 0) { + /* Abort the JIT because __load_pointer() is needed. */ goto out; + } t_offset = func - (image + addrs[i]); EMIT1_off32(0xbe, K); /* mov imm32,%esi */ EMIT1_off32(0xe8, t_offset); /* call */ @@ -489,14 +491,8 @@ common_load: seen |= SEEN_DATAREF; goto common_load; case BPF_S_LDX_B_MSH: if ((int)K < 0) { - if (pc_ret0 > 0) { - /* addrs[pc_ret0 - 1] is the start address */ - EMIT_JMP(addrs[pc_ret0 - 1] - addrs[i]); - break; - } - CLEAR_A(); - EMIT_JMP(cleanup_addr - addrs[i]); - break; + /* Abort the JIT because __load_pointer() is needed. */ + goto out; } seen |= SEEN_DATAREF | SEEN_XREG; t_offset = sk_load_byte_msh - (image + addrs[i]); |