linux-kernel - Re: [PATCH net] bpf: fix allocation warnings in bpf maps and integer overflow

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <565C599B.1020902@iogearbox.net>
Date:	Mon, 30 Nov 2015 15:13:47 +0100
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Dmitry Vyukov <dvyukov@...gle.com>,
	syzkaller <syzkaller@...glegroups.com>
CC:	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	David Miller <davem@...emloft.net>,
	Alexei Starovoitov <ast@...nel.org>,
	netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: [PATCH net] bpf: fix allocation warnings in bpf maps and integer
 overflow

On 11/30/2015 02:57 PM, Dmitry Vyukov wrote:
...
> kamlloc produces a WARNING if you try to allocate more than it ever
> possibly can (KMALLOC_SHIFT_MAX).

Sure, I understand that.

The kzalloc() in array_map_alloc() is however with __GFP_NOWARN flag already.
The warning only triggers in mm if:

   WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));

Your test case is using ca.map_type = 1, which is BPF_MAP_TYPE_HASH. So on
update you're triggering the kmalloc() in htab_map_update_elem().

I'm just asking about the added change in array map.

Thanks,
Daniel
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/