linux-kernel - Re: [PATCH] bpf, x32: Fix bug for BPF_ALU64

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Message-ID: <091c2ed4-a07f-cc75-7b18-1c7cb7068652@iogearbox.net>
Date:   Wed, 1 May 2019 23:43:45 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Wang YanQing <udknight@...il.com>, ast@...nel.org,
        davem@...emloft.net, kuznet@....inr.ac.ru, tglx@...utronix.de,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bpf, x32: Fix bug for BPF_ALU64 | BPF_NEG

On 04/28/2019 04:33 AM, Wang YanQing wrote:
> The current implementation has two errors:
> 1: The second xor instruction will clear carry flag which
>    is necessary for following sbb instruction.
> 2: The select coding for sbb instruction is wrong, the coding
>    is "sbb dreg_hi,ecx", but what we need is "sbb ecx,dreg_hi".
> 
> This patch rewrites the implementation and fixes the errors.
> 
> This patch fixes below errors reported by bpf/test_verifier in x32
> platform when the jit is enabled:
> "
> 0: (b4) w1 = 4
> 1: (b4) w2 = 4
> 2: (1f) r2 -= r1
> 3: (4f) r2 |= r1
> 4: (87) r2 = -r2
> 5: (c7) r2 s>>= 63
> 6: (5f) r1 &= r2
> 7: (bf) r0 = r1
> 8: (95) exit
> processed 9 insns (limit 131072), stack depth 0
> 0: (b4) w1 = 4
> 1: (b4) w2 = 4
> 2: (1f) r2 -= r1
> 3: (4f) r2 |= r1
> 4: (87) r2 = -r2
> 5: (c7) r2 s>>= 63
> 6: (5f) r1 &= r2
> 7: (bf) r0 = r1
> 8: (95) exit
> processed 9 insns (limit 131072), stack depth 0
> ......
> Summary: 1189 PASSED, 125 SKIPPED, 15 FAILED
> "
> 
> Signed-off-by: Wang YanQing <udknight@...il.com>

Applied, thanks!