linux/net
Andrey Ryabinin 40eea803c6 net: sendmsg: fix NULL pointer dereference
Sasha's report:
	> While fuzzing with trinity inside a KVM tools guest running the latest -next
	> kernel with the KASAN patchset, I've stumbled on the following spew:
	>
	> [ 4448.949424] ==================================================================
	> [ 4448.951737] AddressSanitizer: user-memory-access on address 0
	> [ 4448.952988] Read of size 2 by thread T19638:
	> [ 4448.954510] CPU: 28 PID: 19638 Comm: trinity-c76 Not tainted 3.16.0-rc4-next-20140711-sasha-00046-g07d3099-dirty #813
	> [ 4448.956823]  ffff88046d86ca40 0000000000000000 ffff880082f37e78 ffff880082f37a40
	> [ 4448.958233]  ffffffffb6e47068 ffff880082f37a68 ffff880082f37a58 ffffffffb242708d
	> [ 4448.959552]  0000000000000000 ffff880082f37a88 ffffffffb24255b1 0000000000000000
	> [ 4448.961266] Call Trace:
	> [ 4448.963158] dump_stack (lib/dump_stack.c:52)
	> [ 4448.964244] kasan_report_user_access (mm/kasan/report.c:184)
	> [ 4448.965507] __asan_load2 (mm/kasan/kasan.c:352)
	> [ 4448.966482] ? netlink_sendmsg (net/netlink/af_netlink.c:2339)
	> [ 4448.967541] netlink_sendmsg (net/netlink/af_netlink.c:2339)
	> [ 4448.968537] ? get_parent_ip (kernel/sched/core.c:2555)
	> [ 4448.970103] sock_sendmsg (net/socket.c:654)
	> [ 4448.971584] ? might_fault (mm/memory.c:3741)
	> [ 4448.972526] ? might_fault (./arch/x86/include/asm/current.h:14 mm/memory.c:3740)
	> [ 4448.973596] ? verify_iovec (net/core/iovec.c:64)
	> [ 4448.974522] ___sys_sendmsg (net/socket.c:2096)
	> [ 4448.975797] ? put_lock_stats.isra.13 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254)
	> [ 4448.977030] ? lock_release_holdtime (kernel/locking/lockdep.c:273)
	> [ 4448.978197] ? lock_release_non_nested (kernel/locking/lockdep.c:3434 (discriminator 1))
	> [ 4448.979346] ? check_chain_key (kernel/locking/lockdep.c:2188)
	> [ 4448.980535] __sys_sendmmsg (net/socket.c:2181)
	> [ 4448.981592] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600)
	> [ 4448.982773] ? trace_hardirqs_on (kernel/locking/lockdep.c:2607)
	> [ 4448.984458] ? syscall_trace_enter (arch/x86/kernel/ptrace.c:1500 (discriminator 2))
	> [ 4448.985621] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2600)
	> [ 4448.986754] SyS_sendmmsg (net/socket.c:2201)
	> [ 4448.987708] tracesys (arch/x86/kernel/entry_64.S:542)
	> [ 4448.988929] ==================================================================

This reports means that we've come to netlink_sendmsg() with msg->msg_name == NULL and msg->msg_namelen > 0.

After this report there was no usual "Unable to handle kernel NULL pointer dereference"
and this gave me a clue that address 0 is mapped and contains valid socket address structure in it.

This bug was introduced in f3d3342602
(net: rework recvmsg handler msg_name and msg_namelen logic).
Commit message states that:
	"Set msg->msg_name = NULL if user specified a NULL in msg_name but had a
	 non-null msg_namelen in verify_iovec/verify_compat_iovec. This doesn't
	 affect sendto as it would bail out earlier while trying to copy-in the
	 address."
But in fact this affects sendto when address 0 is mapped and contains
socket address structure in it. In such case copy-in address will succeed,
verify_iovec() function will successfully exit with msg->msg_namelen > 0
and msg->msg_name == NULL.

This patch fixes it by setting msg_namelen to 0 if msg_name == NULL.

Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: <stable@vger.kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-07-29 12:20:22 -07:00
..
9p
802
8021q vlan: free percpu stats in device destructor 2014-07-02 17:02:05 -07:00
appletalk appletalk: Fix socket referencing in skb 2014-07-08 19:39:43 -07:00
atm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
ax25
batman-adv batman-adv: fix TT VLAN inconsistency on VLAN re-add 2014-07-21 09:49:30 +02:00
bluetooth Bluetooth: Fix for ACL disconnect when pairing fails 2014-06-20 13:53:54 +02:00
bridge bridge: fix compile error when compiling without IPv6 support 2014-06-12 11:00:24 -07:00
caif
can can: add hash based access to single EFF frame filters 2014-05-19 09:38:24 +02:00
ceph Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2014-06-12 23:06:23 -07:00
core net: sendmsg: fix NULL pointer dereference 2014-07-29 12:20:22 -07:00
dcb net: Use netlink_ns_capable to verify the permisions of netlink messages 2014-04-24 13:44:54 -04:00
dccp net: Eliminate no_check from protosw 2014-05-23 16:28:53 -04:00
decnet net: Split sk_no_check into sk_no_check_{rx,tx} 2014-05-23 16:28:53 -04:00
dns_resolver dns_resolver: Null-terminate the right string 2014-07-20 22:33:32 -07:00
dsa Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-05-24 00:32:30 -04:00
ethernet
hsr
ieee802154 6lowpan_rtnl: fix off by one while fragmentation 2014-06-02 10:39:42 -07:00
ipv4 ip: make IP identifiers less predictable 2014-07-28 18:46:34 -07:00
ipv6 ip: make IP identifiers less predictable 2014-07-28 18:46:34 -07:00
ipx net: Split sk_no_check into sk_no_check_{rx,tx} 2014-05-23 16:28:53 -04:00
irda
iucv af_iucv: correct cleanup if listen backlog is full 2014-05-30 17:35:23 -07:00
key af_key: Replace comma with semicolon 2014-05-30 17:48:58 -07:00
l2tp net/l2tp: don't fall back on UDP [get|set]sockopt 2014-07-14 17:02:31 -07:00
lapb
llc
mac80211 mac80211: fix crash on getting sta info with uninitialized rate control 2014-07-22 22:17:17 +02:00
mac802154 mac802154: don't deliver packets to devices that are down 2014-06-11 12:10:19 -07:00
mpls gre: Call gso_make_checksum 2014-06-04 22:46:38 -07:00
netfilter ipvs: avoid netns exit crash on ip_vs_conn_drop_conntrack 2014-07-16 09:39:28 +09:00
netlabel
netlink netlink: Fix handling of error from netlink_dump(). 2014-07-09 14:33:47 -07:00
netrom
nfc net: add __pskb_copy_fclone and pskb_copy_for_clone 2014-06-11 15:38:02 -07:00
openvswitch openvswitch: Use exact lookup for flow_get and flow_del. 2014-06-30 20:47:15 -07:00
packet net: Use netlink_ns_capable to verify the permisions of netlink messages 2014-04-24 13:44:54 -04:00
phonet net: Use netlink_ns_capable to verify the permisions of netlink messages 2014-04-24 13:44:54 -04:00
rds Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
rfkill Merge git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next 2014-05-22 13:58:36 -04:00
rose
rxrpc af_rxrpc: Fix XDR length check in rxrpc key demarshalling. 2014-05-16 15:24:47 -04:00
sched net_sched: avoid generating same handle for u32 filters 2014-07-20 20:49:17 -07:00
sctp net: sctp: inherit auth_capable on INIT collisions 2014-07-22 19:56:58 -07:00
sunrpc NFSv4: test SECINFO RPC_AUTH_GSS pseudoflavors for support 2014-06-24 18:46:58 -04:00
tipc tipc: clear 'next'-pointer of message fragments before reassembly 2014-07-11 15:02:10 -07:00
unix Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-06-12 14:27:40 -07:00
vmw_vsock vsock: Make transport the proto owner 2014-05-05 13:13:50 -04:00
wimax
wireless cfg80211: fix mic_failure tracing 2014-07-18 09:53:56 +02:00
x25
xfrm xfrm: Fix installation of AH IPsec SAs 2014-06-30 07:42:12 +02:00
Kconfig
Makefile
compat.c net: sendmsg: fix NULL pointer dereference 2014-07-29 12:20:22 -07:00
nonet.c
socket.c
sysctl_net.c