netdev - Re: [PATCH bpf-next] bpf: fix precision bit propagation for BPF

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Date:   Fri, 12 Jul 2019 15:05:43 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Andrii Nakryiko <andriin@...com>, andrii.nakryiko@...il.com,
        ast@...com, bpf@...r.kernel.org, netdev@...r.kernel.org,
        kernel-team@...com
Subject: Re: [PATCH bpf-next] bpf: fix precision bit propagation for BPF_ST
 instructions

On 07/09/2019 05:32 AM, Andrii Nakryiko wrote:
> When backtracking instructions to propagate precision bit for registers
> and stack slots, one class of instructions (BPF_ST) weren't handled
> causing extra stack slots to be propagated into parent state. Parent
> state might not have that much stack allocated, though, which causes
> warning on invalid stack slot usage.
> 
> This patch adds handling of BPF_ST instructions:
> 
> BPF_MEM | <size> | BPF_ST:   *(size *) (dst_reg + off) = imm32
> 
> Reported-by: syzbot+4da3ff23081bafe74fc2@...kaller.appspotmail.com
> Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking")
> Cc: Alexei Starovoitov <ast@...com>
> Signed-off-by: Andrii Nakryiko <andriin@...com>

Applied, thanks!