linux-kernel - Re: [PATCH] seccomp: fix memory leak on filter attach

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: <CAGXu5jK6f2HHzLr9SOR3yzr8tCrDJatcT2csy+gRFpc-Lb46pQ@mail.gmail.com>
Date:	Mon, 14 Apr 2014 10:26:15 -0700
From:	Kees Cook <keescook@...omium.org>
To:	James Morris <james.l.morris@...cle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Masami Ichikawa <masami256@...il.com>,
	Will Drewry <wad@...omium.org>,
	Josh Triplett <josh@...htriplett.org>,
	Rashika Kheria <rashika.kheria@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Paris <eparis@...hat.com>,
	Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH] seccomp: fix memory leak on filter attach

On Mon, Apr 14, 2014 at 10:17 AM, Alexei Starovoitov <ast@...mgrid.com> wrote:
> On Mon, Apr 14, 2014 at 10:11 AM, Kees Cook <keescook@...omium.org> wrote:
>> This sets the correct error code when final filter memory is unavailable,
>> and frees the raw filter no matter what.
>>
>> unreferenced object 0xffff8800d6ea4000 (size 512):
>>   comm "sshd", pid 278, jiffies 4294898315 (age 46.653s)
>>   hex dump (first 32 bytes):
>>     21 00 00 00 04 00 00 00 15 00 01 00 3e 00 00 c0  !...........>...
>>     06 00 00 00 00 00 00 00 21 00 00 00 00 00 00 00  ........!.......
>>   backtrace:
>>     [<ffffffff8151414e>] kmemleak_alloc+0x4e/0xb0
>>     [<ffffffff811a3a40>] __kmalloc+0x280/0x320
>>     [<ffffffff8110842e>] prctl_set_seccomp+0x11e/0x3b0
>>     [<ffffffff8107bb6b>] SyS_prctl+0x3bb/0x4a0
>>     [<ffffffff8152ef2d>] system_call_fastpath+0x1a/0x1f
>>     [<ffffffffffffffff>] 0xffffffffffffffff
>>
>> Reported-by: Masami Ichikawa <masami256@...il.com>
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>> Cc: stable@...r.kernel.org
>
> Acked-by: Alexei Starovoitov <ast@...mgrid.com>
>
>> ---
>>  kernel/seccomp.c |    2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
>> index fd609bd9d6dd..2d7dcdfb7422 100644
>> --- a/kernel/seccomp.c
>> +++ b/kernel/seccomp.c
>> @@ -256,6 +256,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
>>                 goto free_prog;
>>
>>         /* Allocate a new seccomp_filter */
>> +       ret = -ENOMEM;
>>         filter = kzalloc(sizeof(struct seccomp_filter) +
>>                          sizeof(struct sock_filter_int) * new_len,
>>                          GFP_KERNEL|__GFP_NOWARN);
>> @@ -265,6 +266,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog)
>>         ret = sk_convert_filter(fp, fprog->len, filter->insnsi, &new_len);
>>         if (ret)
>>                 goto free_filter;
>> +       kfree(fp);
>>
>>         atomic_set(&filter->usage, 1);
>>         filter->len = new_len;
>> --
>> 1.7.9.5
>>
>>
>> --
>> Kees Cook
>> Chrome OS Security

James (or anyone), can you be sure to pull this soon? I'd like to get
it into 3.14 stable ASAP. Under kernel memory pressure, it would be
possible for the prctl to return 0 without having attached the seccomp
filter.

Thanks!

-Kees

-- 
Kees Cook
Chrome OS Security
--
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/