Ziyang Xuan 8008e797ec ipv6/addrconf: fix a null-ptr-deref bug for ip6_ptr ... commit 85f0173df35e5462d89947135a6a5599c6c3ef6f upstream. Change net device's MTU to smaller than IPV6_MIN_MTU or unregister device while matching route. That may trigger null-ptr-deref bug for ip6_ptr probability as following. ========================================================= BUG: KASAN: null-ptr-deref in find_match.part.0+0x70/0x134 Read of size 4 at addr 0000000000000308 by task ping6/263 CPU: 2 PID: 263 Comm: ping6 Not tainted 5.19.0-rc7+ #14 Call trace: dump_backtrace+0x1a8/0x230 show_stack+0x20/0x70 dump_stack_lvl+0x68/0x84 print_report+0xc4/0x120 kasan_report+0x84/0x120 __asan_load4+0x94/0xd0 find_match.part.0+0x70/0x134 __find_rr_leaf+0x408/0x470 fib6_table_lookup+0x264/0x540 ip6_pol_route+0xf4/0x260 ip6_pol_route_output+0x58/0x70 fib6_rule_lookup+0x1a8/0x330 ip6_route_output_flags_noref+0xd8/0x1a0 ip6_route_output_flags+0x58/0x160 ip6_dst_lookup_tail+0x5b4/0x85c ip6_dst_lookup_flow+0x98/0x120 rawv6_sendmsg+0x49c/0xc70 inet_sendmsg+0x68/0x94 Reproducer as following: Firstly, prepare conditions: $ip netns add ns1 $ip netns add ns2 $ip link add veth1 type veth peer name veth2 $ip link set veth1 netns ns1 $ip link set veth2 netns ns2 $ip netns exec ns1 ip -6 addr add 2001:0db8:0:f101::1/64 dev veth1 $ip netns exec ns2 ip -6 addr add 2001:0db8:0:f101::2/64 dev veth2 $ip netns exec ns1 ifconfig veth1 up $ip netns exec ns2 ifconfig veth2 up $ip netns exec ns1 ip -6 route add 2000::/64 dev veth1 metric 1 $ip netns exec ns2 ip -6 route add 2001::/64 dev veth2 metric 1 Secondly, execute the following two commands in two ssh windows respectively: $ip netns exec ns1 sh $while true; do ip -6 addr add 2001:0db8:0:f101::1/64 dev veth1; ip -6 route add 2000::/64 dev veth1 metric 1; ping6 2000::2; done $ip netns exec ns1 sh $while true; do ip link set veth1 mtu 1000; ip link set veth1 mtu 1500; sleep 5; done It is because ip6_ptr has been assigned to NULL in addrconf_ifdown() firstly, then ip6_ignore_linkdown() accesses ip6_ptr directly without NULL check. cpu0 cpu1 fib6_table_lookup __find_rr_leaf addrconf_notify [ NETDEV_CHANGEMTU ] addrconf_ifdown RCU_INIT_POINTER(dev->ip6_ptr, NULL) find_match ip6_ignore_linkdown So we can add NULL check for ip6_ptr before using in ip6_ignore_linkdown() to fix the null-ptr-deref bug. Fixes: dcd1f57295 ("net/ipv6: Remove fib6_idev") Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com> Reviewed-by: David Ahern <dsahern@kernel.org> Link: https://lore.kernel.org/r/20220728013307.656257-1-william.xuanziyang@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-08-03 12:00:46 +02:00
..
acpi
asm-generic
clocksource
crypto	crypto: drbg - make reseeding from get_random_bytes() synchronous	2022-06-06 08:42:42 +02:00
drm	drm: fix EDID struct for old ARM OABI format	2022-06-09 10:20:59 +02:00
dt-bindings
keys
kunit
kvm
linux	tty: use new tty_insert_flip_string_and_push_buffer() in pty_write()	2022-07-29 17:19:28 +02:00
math-emu
media
memory
misc
net	ipv6/addrconf: fix a null-ptr-deref bug for ip6_ptr	2022-08-03 12:00:46 +02:00
pcmcia
ras
rdma
scsi	scsi: fcoe: Fix Wstringop-overflow warnings in fcoe_wwn_from_mac()	2022-06-09 10:21:15 +02:00
soc
sound	ALSA: jack: Access input_dev under mutex	2022-06-09 10:20:51 +02:00
target
trace	net: sock: tracing: Fix sock_exceed_buf_limit not to dereference stale pointer	2022-07-21 21:20:00 +02:00
uapi	include/uapi/linux/xfrm.h: Fix XFRM_MSG_MAPPING ABI breakage	2022-05-25 09:18:02 +02:00
vdso
video	video: of_display_timing.h: include errno.h	2022-07-12 16:32:19 +02:00
xen