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Message-ID: <333c515e-8b52-0e50-c5d2-529f5fcf0553@fb.com>
Date:   Thu, 19 May 2022 12:22:42 -0700
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Subject: Re: [PATCH bpf v4 1/3] bpf_trace: check size for overflow in
 bpf_kprobe_multi_link_attach
Content-Language: en-US
To:     Eugene Syromiatnikov <esyr@redhat.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>
Cc:     Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
        Shuah Khan <shuah@kernel.org>, linux-kselftest@vger.kernel.org
References: <cover.1652982525.git.esyr@redhat.com>
 <399e634781822329e856103cddba975f58f0498c.1652982525.git.esyr@redhat.com>
From:   Yonghong Song <yhs@fb.com>
In-Reply-To: <399e634781822329e856103cddba975f58f0498c.1652982525.git.esyr@redhat.com>
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On 5/19/22 11:14 AM, Eugene Syromiatnikov wrote:
> Check that size would not overflow before calculation (and return
> -EOVERFLOW if it will), to prevent potential out-of-bounds write
> with the following copy_from_user.  Add the same check
> to kprobe_multi_resolve_syms in case it will be called from elsewhere
> in the future.  The INT_MAX checks are performed in order to avoid
> triggering kvmalloc_node warning [1].
> 
> [1] https://lore.kernel.org/lkml/cfe6abea-8d00-8f8c-f84c-e6f27753b5d1@fb.com/
> 
> Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link")
> Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>

Acked-by: Yonghong Song <yhs@fb.com>