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Groups > linux.kernel > #1514219 > unrolled thread

net/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla

Started byAndrey Konovalov <andreyknvl@google.com>
First post2016-11-03 01:30 +0100
Last post2016-11-03 16:30 +0100
Articles 4 — 2 participants

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  net/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla Andrey Konovalov <andreyknvl@google.com> - 2016-11-03 01:30 +0100
    Re: net/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla Cong Wang <xiyou.wangcong@gmail.com> - 2016-11-03 06:30 +0100
      Re: net/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla Cong Wang <xiyou.wangcong@gmail.com> - 2016-11-03 06:40 +0100
        Re: net/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla Andrey Konovalov <andreyknvl@google.com> - 2016-11-03 16:30 +0100

#1514219 — net/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla

FromAndrey Konovalov <andreyknvl@google.com>
Date2016-11-03 01:30 +0100
Subjectnet/netlink: global-out-of-bounds in genl_family_rcv_msg/validate_nla
Message-ID<sze4N-4Zp-7@gated-at.bofh.it>

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Hi,

I've got the following error report while running the syzkaller fuzzer:

==================================================================
BUG: KASAN: global-out-of-bounds in validate_nla+0x49b/0x4e0 at addr
ffffffff8407e3ac
Read of size 2 by task a.out/3877
Address belongs to variable[<        none        >]
cgroupstats_cmd_get_policy+0xc/0x40 ??:?
CPU: 1 PID: 3877 Comm: a.out Not tainted 4.9.0-rc3+ #336
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffff880063077690 ffffffff81b46934 ffff880063077720 ffffffff847a369f
 ffffffff8407e3a0 ffffffff8407e3ac ffff880063077710 ffffffff8150ac7c
 ffffffff85f44280 ffff88006aec1de8 ffff88006aec1e38 0000000000000286
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff81b46934>] dump_stack+0xb3/0x10f lib/dump_stack.c:51
 [<     inline     >] print_address_description mm/kasan/report.c:204
 [<ffffffff8150ac7c>] kasan_report_error+0x49c/0x4d0 mm/kasan/report.c:283
 [<     inline     >] kasan_report mm/kasan/report.c:303
 [<ffffffff8150ad2e>] __asan_report_load2_noabort+0x3e/0x40
mm/kasan/report.c:322
 [<ffffffff81be27eb>] validate_nla+0x49b/0x4e0 lib/nlattr.c:41
 [<ffffffff81be2ab5>] nla_parse+0x115/0x280 lib/nlattr.c:195
 [<     inline     >] nlmsg_parse ./include/net/netlink.h:386
 [<ffffffff82dc2723>] genl_family_rcv_msg+0x543/0xc80
net/netlink/genetlink.c:613
 [<ffffffff82dc3016>] genl_rcv_msg+0x1b6/0x270 net/netlink/genetlink.c:658
 [<ffffffff82dc10a0>] netlink_rcv_skb+0x2c0/0x3b0 net/netlink/af_netlink.c:2281
 [<ffffffff82dc21c8>] genl_rcv+0x28/0x40 net/netlink/genetlink.c:669
 [<     inline     >] netlink_unicast_kernel net/netlink/af_netlink.c:1214
 [<ffffffff82dbf959>] netlink_unicast+0x5a9/0x880 net/netlink/af_netlink.c:1240
 [<ffffffff82dc05e7>] netlink_sendmsg+0x9b7/0xce0 net/netlink/af_netlink.c:1786
 [<     inline     >] sock_sendmsg_nosec net/socket.c:606
 [<ffffffff82b6f75c>] sock_sendmsg+0xcc/0x110 net/socket.c:616
 [<ffffffff82b6f9c1>] sock_write_iter+0x221/0x3b0 net/socket.c:814
 [<     inline     >] new_sync_write fs/read_write.c:499
 [<ffffffff8151bd44>] __vfs_write+0x334/0x570 fs/read_write.c:512
 [<ffffffff8151f85b>] vfs_write+0x17b/0x500 fs/read_write.c:560
 [<     inline     >] SYSC_write fs/read_write.c:607
 [<ffffffff81523184>] SyS_write+0xd4/0x1a0 fs/read_write.c:599
 [<ffffffff83fc0401>] entry_SYSCALL_64_fastpath+0x1f/0xc2
arch/x86/entry/entry_64.S:209
Memory state around the buggy address:
 ffffffff8407e280: 00 02 fa fa fa fa fa fa 00 00 00 00 02 fa fa fa
 ffffffff8407e300: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff8407e380: fa fa fa fa 00 fa fa fa fa fa fa fa 00 00 04 fa
                                  ^
 ffffffff8407e400: fa fa fa fa 00 00 00 00 00 02 fa fa fa fa fa fa
 ffffffff8407e480: 00 00 00 03 fa fa fa fa 00 00 00 00 00 01 fa fa
==================================================================

A reproducer is attached.

On commit 0c183d92b20b5c84ca655b45ef57b3318b83eb9e (Oct 31).

Thanks!

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#1514295

FromCong Wang <xiyou.wangcong@gmail.com>
Date2016-11-03 06:30 +0100
Message-ID<sziL8-84G-3@gated-at.bofh.it>
In reply to#1514219
On Wed, Nov 2, 2016 at 5:25 PM, Andrey Konovalov <andreyknvl@google.com> wrote:
> Hi,
>
> I've got the following error report while running the syzkaller fuzzer:
>
> ==================================================================
> BUG: KASAN: global-out-of-bounds in validate_nla+0x49b/0x4e0 at addr
> ffffffff8407e3ac
> Read of size 2 by task a.out/3877
> Address belongs to variable[<        none        >]
> cgroupstats_cmd_get_policy+0xc/0x40 ??:?

Seems taskstats doesn't use genetlink correctly, CGROUPSTATS_CMD_ATTR_FD
is not within 0~TASKSTATS_CMD_ATTR_MAX.

I guess we need the following patch, but it certainly breaks user-space... :-/

diff --git a/include/uapi/linux/cgroupstats.h b/include/uapi/linux/cgroupstats.h
index 3753c33..b5c120c 100644
--- a/include/uapi/linux/cgroupstats.h
+++ b/include/uapi/linux/cgroupstats.h
@@ -61,7 +61,7 @@ enum {
 #define CGROUPSTATS_TYPE_MAX (__CGROUPSTATS_TYPE_MAX - 1)

 enum {
-       CGROUPSTATS_CMD_ATTR_UNSPEC = 0,
+       CGROUPSTATS_CMD_ATTR_UNSPEC = __TASKSTATS_CMD_ATTR_MAX,
        CGROUPSTATS_CMD_ATTR_FD,
        __CGROUPSTATS_CMD_ATTR_MAX,
 };
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index b3f05ee..78502b0 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -45,7 +45,7 @@ static struct genl_family family = {
        .id             = GENL_ID_GENERATE,
        .name           = TASKSTATS_GENL_NAME,
        .version        = TASKSTATS_GENL_VERSION,
-       .maxattr        = TASKSTATS_CMD_ATTR_MAX,
+       .maxattr        = CGROUPSTATS_CMD_ATTR_MAX,
 };

 static const struct nla_policy
taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {

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#1514297

FromCong Wang <xiyou.wangcong@gmail.com>
Date2016-11-03 06:40 +0100
Message-ID<sziUN-87D-3@gated-at.bofh.it>
In reply to#1514295
On Wed, Nov 2, 2016 at 10:25 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Wed, Nov 2, 2016 at 5:25 PM, Andrey Konovalov <andreyknvl@google.com> wrote:
>> Hi,
>>
>> I've got the following error report while running the syzkaller fuzzer:
>>
>> ==================================================================
>> BUG: KASAN: global-out-of-bounds in validate_nla+0x49b/0x4e0 at addr
>> ffffffff8407e3ac
>> Read of size 2 by task a.out/3877
>> Address belongs to variable[<        none        >]
>> cgroupstats_cmd_get_policy+0xc/0x40 ??:?
>
> Seems taskstats doesn't use genetlink correctly, CGROUPSTATS_CMD_ATTR_FD
> is not within 0~TASKSTATS_CMD_ATTR_MAX.
>
> I guess we need the following patch, but it certainly breaks user-space... :-/


Wait, maybe just this one-line fix is enough:

diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index b3f05ee..e6b342e 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -54,7 +54,7 @@ static const struct nla_policy
taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1
        [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
        [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};

-static const struct nla_policy
cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
+static const struct nla_policy
cgroupstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
        [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
 };

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#1514609

FromAndrey Konovalov <andreyknvl@google.com>
Date2016-11-03 16:30 +0100
Message-ID<szs7L-5Cd-31@gated-at.bofh.it>
In reply to#1514297
Hi Cong,

Yes, the last patch fixes the issue.

Tested-by: Andrey Konovalov <andreyknvl@google.com>

Thanks!

On Thu, Nov 3, 2016 at 6:29 AM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Wed, Nov 2, 2016 at 10:25 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> On Wed, Nov 2, 2016 at 5:25 PM, Andrey Konovalov <andreyknvl@google.com> wrote:
>>> Hi,
>>>
>>> I've got the following error report while running the syzkaller fuzzer:
>>>
>>> ==================================================================
>>> BUG: KASAN: global-out-of-bounds in validate_nla+0x49b/0x4e0 at addr
>>> ffffffff8407e3ac
>>> Read of size 2 by task a.out/3877
>>> Address belongs to variable[<        none        >]
>>> cgroupstats_cmd_get_policy+0xc/0x40 ??:?
>>
>> Seems taskstats doesn't use genetlink correctly, CGROUPSTATS_CMD_ATTR_FD
>> is not within 0~TASKSTATS_CMD_ATTR_MAX.
>>
>> I guess we need the following patch, but it certainly breaks user-space... :-/
>
>
> Wait, maybe just this one-line fix is enough:
>
> diff --git a/kernel/taskstats.c b/kernel/taskstats.c
> index b3f05ee..e6b342e 100644
> --- a/kernel/taskstats.c
> +++ b/kernel/taskstats.c
> @@ -54,7 +54,7 @@ static const struct nla_policy
> taskstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1
>         [TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
>         [TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};
>
> -static const struct nla_policy
> cgroupstats_cmd_get_policy[CGROUPSTATS_CMD_ATTR_MAX+1] = {
> +static const struct nla_policy
> cgroupstats_cmd_get_policy[TASKSTATS_CMD_ATTR_MAX+1] = {
>         [CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
>  };

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