From: Eugene Syromiatnikov <esyr@redhat.com>
To: Yonghong Song <yhs@fb.com>
Cc: 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>,
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
Subject: Re: [PATCH bpf v3 1/2] bpf_trace: check size for overflow in bpf_kprobe_multi_link_attach
Date: Wed, 18 May 2022 22:00:10 +0200 [thread overview]
Message-ID: <20220518200010.GA29226@asgard.redhat.com> (raw)
In-Reply-To: <412bf136-6a5b-f442-1e84-778697e2b694@fb.com>
On Wed, May 18, 2022 at 09:34:22AM -0700, Yonghong Song wrote:
> On 5/18/22 5:22 AM, Eugene Syromiatnikov wrote:
> >- size = cnt * sizeof(*syms);
> >+ if (check_mul_overflow(cnt, (u32)sizeof(*syms), &size))
> >+ return -EOVERFLOW;
>
> In mm/util.c kvmalloc_node(), we have
>
> /* Don't even allow crazy sizes */
> if (unlikely(size > INT_MAX)) {
> WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> return NULL;
> }
>
> Basically the maximum size to be allocated in INT_MAX.
>
> Here, we have 'size' as u32, which means if the size is 0xffff0000,
> the check_mul_overflow will return false (no overflow) but
> kvzalloc will still have a warning.
>
> I think we should change the type of 'size' to be 'int' which
> should catch the above case and be consistent with
> what kvmalloc_node() intends to warn.
Huh, it's a bitmore complicated as check_mul_overflow requires types to
match; what do you think about
+ if (check_mul_overflow(cnt, (u32)sizeof(*syms), &size) || size > INT_MAX)
?
next prev parent reply other threads:[~2022-05-18 20:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-18 12:22 [PATCH bpf v3 0/2] Fix kprobe_multi interface issues for 5.18 Eugene Syromiatnikov
2022-05-18 12:22 ` [PATCH bpf v3 1/2] bpf_trace: check size for overflow in bpf_kprobe_multi_link_attach Eugene Syromiatnikov
2022-05-18 16:34 ` Yonghong Song
2022-05-18 20:00 ` Eugene Syromiatnikov [this message]
2022-05-18 20:41 ` Yonghong Song
2022-05-18 12:22 ` [PATCH bpf v3 2/2] bpf_trace: bail out from bpf_kprobe_multi_link_attach when in compat Eugene Syromiatnikov
2022-05-18 16:55 ` Yonghong Song
2022-05-18 20:03 ` Eugene Syromiatnikov
2022-05-18 20:57 ` Yonghong Song
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