linux_dsm_epyc7002/net
Daniel Borkmann 600ddd6825 net: sctp: fix slab corruption from use after free on INIT collisions
When hitting an INIT collision case during the 4WHS with AUTH enabled, as
already described in detail in commit 1be9a950c6 ("net: sctp: inherit
auth_capable on INIT collisions"), it can happen that we occasionally
still remotely trigger the following panic on server side which seems to
have been uncovered after the fix from commit 1be9a950c6 ...

[  533.876389] BUG: unable to handle kernel paging request at 00000000ffffffff
[  533.913657] IP: [<ffffffff811ac385>] __kmalloc+0x95/0x230
[  533.940559] PGD 5030f2067 PUD 0
[  533.957104] Oops: 0000 [#1] SMP
[  533.974283] Modules linked in: sctp mlx4_en [...]
[  534.939704] Call Trace:
[  534.951833]  [<ffffffff81294e30>] ? crypto_init_shash_ops+0x60/0xf0
[  534.984213]  [<ffffffff81294e30>] crypto_init_shash_ops+0x60/0xf0
[  535.015025]  [<ffffffff8128c8ed>] __crypto_alloc_tfm+0x6d/0x170
[  535.045661]  [<ffffffff8128d12c>] crypto_alloc_base+0x4c/0xb0
[  535.074593]  [<ffffffff8160bd42>] ? _raw_spin_lock_bh+0x12/0x50
[  535.105239]  [<ffffffffa0418c11>] sctp_inet_listen+0x161/0x1e0 [sctp]
[  535.138606]  [<ffffffff814e43bd>] SyS_listen+0x9d/0xb0
[  535.166848]  [<ffffffff816149a9>] system_call_fastpath+0x16/0x1b

... or depending on the the application, for example this one:

[ 1370.026490] BUG: unable to handle kernel paging request at 00000000ffffffff
[ 1370.026506] IP: [<ffffffff811ab455>] kmem_cache_alloc+0x75/0x1d0
[ 1370.054568] PGD 633c94067 PUD 0
[ 1370.070446] Oops: 0000 [#1] SMP
[ 1370.085010] Modules linked in: sctp kvm_amd kvm [...]
[ 1370.963431] Call Trace:
[ 1370.974632]  [<ffffffff8120f7cf>] ? SyS_epoll_ctl+0x53f/0x960
[ 1371.000863]  [<ffffffff8120f7cf>] SyS_epoll_ctl+0x53f/0x960
[ 1371.027154]  [<ffffffff812100d3>] ? anon_inode_getfile+0xd3/0x170
[ 1371.054679]  [<ffffffff811e3d67>] ? __alloc_fd+0xa7/0x130
[ 1371.080183]  [<ffffffff816149a9>] system_call_fastpath+0x16/0x1b

With slab debugging enabled, we can see that the poison has been overwritten:

[  669.826368] BUG kmalloc-128 (Tainted: G        W     ): Poison overwritten
[  669.826385] INFO: 0xffff880228b32e50-0xffff880228b32e50. First byte 0x6a instead of 0x6b
[  669.826414] INFO: Allocated in sctp_auth_create_key+0x23/0x50 [sctp] age=3 cpu=0 pid=18494
[  669.826424]  __slab_alloc+0x4bf/0x566
[  669.826433]  __kmalloc+0x280/0x310
[  669.826453]  sctp_auth_create_key+0x23/0x50 [sctp]
[  669.826471]  sctp_auth_asoc_create_secret+0xcb/0x1e0 [sctp]
[  669.826488]  sctp_auth_asoc_init_active_key+0x68/0xa0 [sctp]
[  669.826505]  sctp_do_sm+0x29d/0x17c0 [sctp] [...]
[  669.826629] INFO: Freed in kzfree+0x31/0x40 age=1 cpu=0 pid=18494
[  669.826635]  __slab_free+0x39/0x2a8
[  669.826643]  kfree+0x1d6/0x230
[  669.826650]  kzfree+0x31/0x40
[  669.826666]  sctp_auth_key_put+0x19/0x20 [sctp]
[  669.826681]  sctp_assoc_update+0x1ee/0x2d0 [sctp]
[  669.826695]  sctp_do_sm+0x674/0x17c0 [sctp]

Since this only triggers in some collision-cases with AUTH, the problem at
heart is that sctp_auth_key_put() on asoc->asoc_shared_key is called twice
when having refcnt 1, once directly in sctp_assoc_update() and yet again
from within sctp_auth_asoc_init_active_key() via sctp_assoc_update() on
the already kzfree'd memory, which is also consistent with the observation
of the poison decrease from 0x6b to 0x6a (note: the overwrite is detected
at a later point in time when poison is checked on new allocation).

Reference counting of auth keys revisited:

Shared keys for AUTH chunks are being stored in endpoints and associations
in endpoint_shared_keys list. On endpoint creation, a null key is being
added; on association creation, all endpoint shared keys are being cached
and thus cloned over to the association. struct sctp_shared_key only holds
a pointer to the actual key bytes, that is, struct sctp_auth_bytes which
keeps track of users internally through refcounting. Naturally, on assoc
or enpoint destruction, sctp_shared_key are being destroyed directly and
the reference on sctp_auth_bytes dropped.

User space can add keys to either list via setsockopt(2) through struct
sctp_authkey and by passing that to sctp_auth_set_key() which replaces or
adds a new auth key. There, sctp_auth_create_key() creates a new sctp_auth_bytes
with refcount 1 and in case of replacement drops the reference on the old
sctp_auth_bytes. A key can be set active from user space through setsockopt()
on the id via sctp_auth_set_active_key(), which iterates through either
endpoint_shared_keys and in case of an assoc, invokes (one of various places)
sctp_auth_asoc_init_active_key().

sctp_auth_asoc_init_active_key() computes the actual secret from local's
and peer's random, hmac and shared key parameters and returns a new key
directly as sctp_auth_bytes, that is asoc->asoc_shared_key, plus drops
the reference if there was a previous one. The secret, which where we
eventually double drop the ref comes from sctp_auth_asoc_set_secret() with
intitial refcount of 1, which also stays unchanged eventually in
sctp_assoc_update(). This key is later being used for crypto layer to
set the key for the hash in crypto_hash_setkey() from sctp_auth_calculate_hmac().

To close the loop: asoc->asoc_shared_key is freshly allocated secret
material and independant of the sctp_shared_key management keeping track
of only shared keys in endpoints and assocs. Hence, also commit 4184b2a79a
("net: sctp: fix memory leak in auth key management") is independant of
this bug here since it concerns a different layer (though same structures
being used eventually). asoc->asoc_shared_key is reference dropped correctly
on assoc destruction in sctp_association_free() and when active keys are
being replaced in sctp_auth_asoc_init_active_key(), it always has a refcount
of 1. Hence, it's freed prematurely in sctp_assoc_update(). Simple fix is
to remove that sctp_auth_key_put() from there which fixes these panics.

Fixes: 730fc3d05c ("[SCTP]: Implete SCTP-AUTH parameter processing")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-26 17:02:05 -08:00
..
6lowpan net/6lowpan: Remove FSF address from GPL statement. 2014-12-05 12:43:04 +01:00
9p 9p/trans_virtio: enable VQs early 2014-10-15 10:25:04 +10:30
802 net: set name_assign_type in alloc_netdev() 2014-07-15 16:12:48 -07:00
8021q vlan: Add ability to always enable TSO/UFO 2014-12-12 10:58:53 -05:00
appletalk new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
atm put iov_iter into msghdr 2014-12-09 16:29:03 -05:00
ax25 new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
batman-adv batman-adv: fix potential TT client + orig-node memory leak 2015-01-06 11:07:01 +01:00
bluetooth Bluetooth: Fix accepting connections when not using mgmt 2014-12-24 20:02:00 +01:00
bridge bridge: only provide proxy ARP when CONFIG_INET is enabled 2015-01-14 15:08:02 -05:00
caif put iov_iter into msghdr 2014-12-09 16:29:03 -05:00
can can: fix spelling errors 2014-12-07 21:22:05 +01:00
ceph libceph: fix sparse endianness warnings 2015-01-08 20:36:57 +03:00
core net: rps: fix cpu unplug 2015-01-16 01:02:42 -05:00
dcb dcbnl : Disable software interrupts before taking dcb_lock 2014-11-16 14:50:52 -05:00
dccp net: introduce helper macro for_each_cmsghdr 2014-12-10 22:41:55 -05:00
decnet new helper: memcpy_to_msg() 2014-11-24 04:28:51 -05:00
dns_resolver Merge commit 'v3.16' into next 2014-10-01 00:44:04 +10:00
dsa net: dsa: set slave MII bus PHY mask 2015-01-25 16:00:54 -08:00
ethernet net: Add function for parsing the header length out of linear ethernet frames 2014-09-05 17:47:02 -07:00
hsr net/hsr: Remove left-over never-true conditional code. 2014-07-11 15:04:40 -07:00
ieee802154 Merge tag 'master-2014-12-08' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next 2014-12-09 18:12:03 -05:00
ipv4 ip: zero sockaddr returned on error queue 2015-01-15 19:41:16 -05:00
ipv6 ipv6: Fix __ip6_route_redirect 2015-01-25 22:09:51 -08:00
ipx switch ipxrtr_route_packet() from iovec to msghdr 2014-11-24 04:28:49 -05:00
irda irda: Convert function pointer arrays and uses to const 2014-12-10 15:33:16 -05:00
iucv net: introduce helper macro for_each_cmsghdr 2014-12-10 22:41:55 -05:00
key new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
l2tp ip_generic_getfrag, udplite_getfrag: switch to passing msghdr 2014-12-09 16:28:22 -05:00
lapb lapb: move EXPORT_SYMBOL after functions. 2014-10-24 15:51:42 -04:00
llc net: llc: use correct size for sysctl timeout entries 2015-01-25 00:23:21 -08:00
mac80211 mac80211: uninitialized return val in __ieee80211_sta_handle_tspec_ac_params 2015-01-07 13:57:34 +01:00
mac802154 mac802154: use goto label on failure 2014-12-05 14:18:42 +01:00
mpls mpls: Fix allowed protocols for mpls gso 2014-12-23 23:57:31 -05:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2015-01-12 00:14:49 -05:00
netlabel netlabel: kernel-doc warning fix 2014-10-09 01:40:05 -04:00
netlink genetlink: synchronize socket closing and family removal 2015-01-16 17:04:25 -05:00
netrom new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
nfc Merge tag 'master-2014-12-08' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next 2014-12-09 18:12:03 -05:00
openvswitch openvswitch: packet messages need their own probe attribtue 2015-01-14 16:49:44 -05:00
packet packet: bail out of packet_snd() if L2 header creation fails 2015-01-11 21:54:03 -05:00
phonet new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
rds rds: Fix min() warning in rds_message_inc_copy_to_user() 2014-12-15 11:49:09 -05:00
rfkill Driver core patches for 3.19-rc1 2014-12-14 16:10:09 -08:00
rose new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
rxrpc net: introduce helper macro for_each_cmsghdr 2014-12-10 22:41:55 -05:00
sched net: cls_bpf: fix auto generation of per list handles 2015-01-26 15:50:19 -08:00
sctp net: sctp: fix slab corruption from use after free on INIT collisions 2015-01-26 17:02:05 -08:00
sunrpc rpc: fix xdr_truncate_encode to handle buffer ending on page boundary 2015-01-07 14:03:58 -05:00
switchdev bridge: call netdev_sw_port_stp_update when bridge port STP status changes 2014-12-02 20:01:22 -08:00
tipc tipc: fix bug in broadcast retransmit code 2015-01-12 16:01:59 -05:00
unix put iov_iter into msghdr 2014-12-09 16:29:03 -05:00
vmw_vsock put iov_iter into msghdr 2014-12-09 16:29:03 -05:00
wimax wimax: convert printk to pr_foo() 2014-10-07 20:28:44 -04:00
wireless Just two fixes - one for an uninialized variable and 2015-01-15 19:28:36 -05:00
x25 new helper: memcpy_from_msg() 2014-11-24 04:28:48 -05:00
xfrm Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2014-12-08 21:30:21 -05:00
compat.c put iov_iter into msghdr 2014-12-09 16:29:03 -05:00
Kconfig net: introduce generic switch devices support 2014-12-02 20:01:20 -08:00
Makefile Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-12-16 15:53:03 -08:00
socket.c [regression] chunk lost from bd9b51 2014-12-19 07:13:21 -05:00
sysctl_net.c