lkml.org 
[lkml]   [2013]   [Mar]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 1/2] userns: Stop oopsing in key_change_session_keyring

Dave Jones <davej@redhat.com> writes:
> Just hit this on Linus' current tree.
>
> [ 89.621770] BUG: unable to handle kernel NULL pointer dereference at 00000000000000c8
> [ 89.623111] IP: [<ffffffff810784b0>] commit_creds+0x250/0x2f0
> [ 89.624062] PGD 122bfd067 PUD 122bfe067 PMD 0
> [ 89.624901] Oops: 0000 [#1] PREEMPT SMP
> [ 89.625678] Modules linked in: caif_socket caif netrom bridge hidp 8021q garp stp mrp rose llc2 af_rxrpc phonet af_key binfmt_misc bnep l2tp_ppp can_bcm l2tp_core pppoe pppox can_raw scsi_transport_iscsi ppp_generic slhc nfnetlink can ipt_ULOG ax25 decnet irda nfc rds x25 crc_ccitt appletalk atm ipx p8023 psnap p8022 llc lockd sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_conntrack nf_conntrack ip6table_filter ip6_tables btusb bluetooth snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_pcm vhost_net snd_page_alloc snd_timer tun macvtap usb_debug snd rfkill microcode macvlan edac_core pcspkr serio_raw kvm_amd soundcore kvm r8169 mii
> [ 89.637846] CPU 2
> [ 89.638175] Pid: 782, comm: trinity-main Not tainted 3.8.0+ #63 Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H
> [ 89.639850] RIP: 0010:[<ffffffff810784b0>] [<ffffffff810784b0>] commit_creds+0x250/0x2f0
> [ 89.641161] RSP: 0018:ffff880115657eb8 EFLAGS: 00010207
> [ 89.641984] RAX: 00000000000003e8 RBX: ffff88012688b000 RCX: 0000000000000000
> [ 89.643069] RDX: 0000000000000000 RSI: ffffffff81c32960 RDI: ffff880105839600
> [ 89.644167] RBP: ffff880115657ed8 R08: 0000000000000000 R09: 0000000000000000
> [ 89.645254] R10: 0000000000000001 R11: 0000000000000246 R12: ffff880105839600
> [ 89.646340] R13: ffff88011beea490 R14: ffff88011beea490 R15: 0000000000000000
> [ 89.647431] FS: 00007f3ac063b740(0000) GS:ffff88012b200000(0000) knlGS:0000000000000000
> [ 89.648660] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 89.649548] CR2: 00000000000000c8 CR3: 0000000122bfc000 CR4: 00000000000007e0
> [ 89.650635] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 89.651723] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 89.652812] Process trinity-main (pid: 782, threadinfo ffff880115656000, task ffff88011beea490)
> [ 89.654128] Stack:
> [ 89.654433] 0000000000000000 ffff8801058396a0 ffff880105839600 ffff88011beeaa78
> [ 89.655769] ffff880115657ef8 ffffffff812c7d9b ffffffff82079be0 0000000000000000
> [ 89.657073] ffff880115657f28 ffffffff8106c665 0000000000000002 ffff880115657f58
> [ 89.658399] Call Trace:
> [ 89.658822] [<ffffffff812c7d9b>] key_change_session_keyring+0xfb/0x140
> [ 89.659845] [<ffffffff8106c665>] task_work_run+0xa5/0xd0
> [ 89.660698] [<ffffffff81002911>] do_notify_resume+0x71/0xb0
> [ 89.661581] [<ffffffff816c9a4a>] int_signal+0x12/0x17
> [ 89.662385] Code: 24 90 00 00 00 48 8b b3 90 00 00 00 49 8b 4c 24 40 48 39 f2 75 08 e9 83 00 00 00 48 89 ca 48 81 fa 60 29 c3 81 0f 84 41 fe ff ff <48> 8b 8a c8 00 00 00 48 39 ce 75 e4 3b 82 d0 00 00 00 0f 84 4b
> [ 89.667778] RIP [<ffffffff810784b0>] commit_creds+0x250/0x2f0
> [ 89.668733] RSP <ffff880115657eb8>
> [ 89.669301] CR2: 00000000000000c8
>
> My fastest trinity induced oops yet!
>
>
> Appears to be..
>
> if ((set_ns == subset_ns->parent) &&
> 850: 48 8b 8a c8 00 00 00 mov 0xc8(%rdx),%rcx
>
> from the inlined cred_cap_issubset

By historical accident we have been reading trying to set new->user_ns
from new->user_ns. Which is totally silly as new->user_ns is NULL (as
is every other field in new except session_keyring at that point).

The intent is clearly to copy all of the fields from old to new so copy
old->user_ns into into new->user_ns.

Cc: stable@vger.kernel.org
Reported-by: Dave Jones <davej@redhat.com>
Tested-by: Dave Jones <davej@redhat.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
security/keys/process_keys.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 58dfe08..a571fad 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -839,7 +839,7 @@ void key_change_session_keyring(struct callback_head *twork)
new-> sgid = old-> sgid;
new->fsgid = old->fsgid;
new->user = get_uid(old->user);
- new->user_ns = get_user_ns(new->user_ns);
+ new->user_ns = get_user_ns(old->user_ns);
new->group_info = get_group_info(old->group_info);

new->securebits = old->securebits;
--
1.7.5.4


\
 
 \ /
  Last update: 2013-03-04 09:42    [W:0.083 / U:0.636 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site