[PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation

[PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation

[Indan Zupancic]

Hello,

Finally, after much searching I found one little bug.

[PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation

Small typo resulted in bad code generation for certain
values of K for the BPF_S_ALU_AND_K instruction.

Signed-off-by: Indan Zupancic <indan@nul.nu>
---

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 7c1b765..28bc807 100644
--- 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 *fp)
 					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 */
 				}

Re: [PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation

[Eric Dumazet]

On Sat, 2012-03-31 at 20:52 +1100, Indan Zupancic wrote:
> Hello,
> 
> Finally, after much searching I found one little bug.
> 
> [PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation
> 
> Small typo resulted in bad code generation for certain
> values of K for the BPF_S_ALU_AND_K instruction.
> 
> Signed-off-by: Indan Zupancic <indan@nul.nu>
> ---
> 
> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> index 7c1b765..28bc807 100644
> --- 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 *fp)
>  					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 */
>  				}
> 
> 

Thanks but it was already fixed.

commit 1d24fb3684f347226747c6b11ea426b7b992694e
Author: zhuangfeiran@ict.ac.cn <zhuangfeiran@ict.ac.cn>
Date:   Wed Mar 28 23:27:00 2012 +0000

    x86 bpf_jit: fix a bug in emitting the 16-bit immediate operand of AND
    
    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@ict.ac.cn>
    Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>

Re: [PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation

[Greg KH]

On Sat, Mar 31, 2012 at 08:52:09PM +1100, Indan Zupancic wrote:
> Hello,
> 
> Finally, after much searching I found one little bug.
> 
> [PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation
> 
> Small typo resulted in bad code generation for certain
> values of K for the BPF_S_ALU_AND_K instruction.
> 
> Signed-off-by: Indan Zupancic <indan@nul.nu>
> ---
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>

Re: [PATCH] net: bpf_jit: fix BPF_S_ALU_AND_K compilation

[Indan Zupancic]

On Sun, April 1, 2012 01:13, Greg KH wrote:
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
> for how to do this properly.
>
> </formletter>

Thanks for pointing that out. It won't happen again.

Greetings,

Indan