[ 01/42] x86 bpf_jit: fix a bug in emitting the 16-bit immediate operand of AND

From: Greg KH
Date: Wed Apr 11 2012 - 19:27:35 EST


3.0-stable review patch. If anyone has any objections, please let me know.

------------------


From: "zhuangfeiran@xxxxxxxxx" <zhuangfeiran@xxxxxxxxx>

[ Upstream commit 1d24fb3684f347226747c6b11ea426b7b992694e ]

When K >= 0xFFFF0000, AND needs the two least significant bytes of K as
its operand, but EMIT2() gives it the least significant byte of K and
0x2. EMIT() should be used here to replace EMIT2().

Signed-off-by: Feiran Zhuang <zhuangfeiran@xxxxxxxxx>
Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -289,7 +289,7 @@ void bpf_jit_compile(struct sk_filter *f
EMIT2(0x24, K & 0xFF); /* and imm8,%al */
} else if (K >= 0xFFFF0000) {
EMIT2(0x66, 0x25); /* and imm16,%ax */
- EMIT2(K, 2);
+ EMIT(K, 2);
} else {
EMIT1_off32(0x25, K); /* and imm32,%eax */
}


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