[PATCH 5.5 022/176] net: add strict checks in netdev_name_node_alt_destroy()

From: Greg Kroah-Hartman
Date: Tue Mar 03 2020 - 12:45:13 EST

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From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit e08ad80551b4b33c02f2fce1522f6c227d3976cf ]

netdev_name_node_alt_destroy() does a lookup over all
device names of a namespace.

We need to make sure the name belongs to the device
of interest, and that we do not destroy its primary
name, since we rely on it being not deleted :
dev->name_node would indeed point to freed memory.

syzbot report was the following :

BUG: KASAN: use-after-free in dev_net include/linux/netdevice.h:2206 [inline]
BUG: KASAN: use-after-free in mld_force_mld_version net/ipv6/mcast.c:1172 [inline]
BUG: KASAN: use-after-free in mld_in_v2_mode_only net/ipv6/mcast.c:1180 [inline]
BUG: KASAN: use-after-free in mld_in_v1_mode+0x203/0x230 net/ipv6/mcast.c:1190
Read of size 8 at addr ffff88809886c588 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
__kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:641
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
dev_net include/linux/netdevice.h:2206 [inline]
mld_force_mld_version net/ipv6/mcast.c:1172 [inline]
mld_in_v2_mode_only net/ipv6/mcast.c:1180 [inline]
mld_in_v1_mode+0x203/0x230 net/ipv6/mcast.c:1190
mld_send_initial_cr net/ipv6/mcast.c:2083 [inline]
mld_dad_timer_expire+0x24/0x230 net/ipv6/mcast.c:2118
call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1404
expire_timers kernel/time/timer.c:1449 [inline]
__run_timers kernel/time/timer.c:1773 [inline]
__run_timers kernel/time/timer.c:1740 [inline]
run_timer_softirq+0x6c3/0x1790 kernel/time/timer.c:1786
__do_softirq+0x262/0x98c kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x19b/0x1e0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1146
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
</IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 68 73 c5 f9 eb 8a cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d 94 be 59 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 84 be 59 00 fb f4 <c3> cc 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 de 2a 74 f9 e8 09
RSP: 0018:ffffc90000d3fd68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff136761a RBX: ffff8880a99fc340 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a99fcbd4
RBP: ffffc90000d3fd98 R08: ffff8880a99fc340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff8aa5a1c0 R14: 0000000000000000 R15: 0000000000000001
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:686
default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x3c8/0x6e0 kernel/sched/idle.c:269
cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
start_secondary+0x2f4/0x410 arch/x86/kernel/smpboot.c:264
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Allocated by task 10229:
save_stack+0x23/0x90 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
__kasan_kmalloc mm/kasan/common.c:515 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488
kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
__do_kmalloc_node mm/slab.c:3616 [inline]
__kmalloc_node+0x4e/0x70 mm/slab.c:3623
kmalloc_node include/linux/slab.h:578 [inline]
kvmalloc_node+0x68/0x100 mm/util.c:574
kvmalloc include/linux/mm.h:645 [inline]
kvzalloc include/linux/mm.h:653 [inline]
alloc_netdev_mqs+0x98/0xe40 net/core/dev.c:9797
rtnl_create_link+0x22d/0xaf0 net/core/rtnetlink.c:3047
__rtnl_newlink+0xf9f/0x1790 net/core/rtnetlink.c:3309
rtnl_newlink+0x69/0xa0 net/core/rtnetlink.c:3377
rtnetlink_rcv_msg+0x45e/0xaf0 net/core/rtnetlink.c:5438
netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5456
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0x59e/0x7e0 net/netlink/af_netlink.c:1328
netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:672
__sys_sendto+0x262/0x380 net/socket.c:1998
__do_compat_sys_socketcall net/compat.c:771 [inline]
__se_compat_sys_socketcall net/compat.c:719 [inline]
__ia32_compat_sys_socketcall+0x530/0x710 net/compat.c:719
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 10229:
save_stack+0x23/0x90 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
kasan_set_free_info mm/kasan/common.c:337 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
__cache_free mm/slab.c:3426 [inline]
kfree+0x10a/0x2c0 mm/slab.c:3757
__netdev_name_node_alt_destroy+0x1ff/0x2a0 net/core/dev.c:322
netdev_name_node_alt_destroy+0x57/0x80 net/core/dev.c:334
rtnl_alt_ifname net/core/rtnetlink.c:3518 [inline]
rtnl_linkprop.isra.0+0x575/0x6f0 net/core/rtnetlink.c:3567
rtnl_dellinkprop+0x46/0x60 net/core/rtnetlink.c:3588
rtnetlink_rcv_msg+0x45e/0xaf0 net/core/rtnetlink.c:5438
netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5456
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0x59e/0x7e0 net/netlink/af_netlink.c:1328
netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:672
____sys_sendmsg+0x753/0x880 net/socket.c:2343
___sys_sendmsg+0x100/0x170 net/socket.c:2397
__sys_sendmsg+0x105/0x1d0 net/socket.c:2430
__compat_sys_sendmsg net/compat.c:642 [inline]
__do_compat_sys_sendmsg net/compat.c:649 [inline]
__se_compat_sys_sendmsg net/compat.c:646 [inline]
__ia32_compat_sys_sendmsg+0x7a/0xb0 net/compat.c:646
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

The buggy address belongs to the object at ffff88809886c000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1416 bytes inside of
4096-byte region [ffff88809886c000, ffff88809886d000)
The buggy address belongs to the page:
page:ffffea0002621b00 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002610d08 ffffea0002607608 ffff8880aa402000
raw: 0000000000000000 ffff88809886c000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809886c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809886c500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809886c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809886c600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809886c680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Fixes: 36fbf1e52bd3 ("net: rtnetlink: add linkprop commands to add and delete alternative ifnames")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Cc: Jiri Pirko <jiri@xxxxxxxxxxxx>
Acked-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/dev.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -330,6 +330,12 @@ int netdev_name_node_alt_destroy(struct
name_node = netdev_name_node_lookup(net, name);
if (!name_node)
return -ENOENT;
+ /* lookup might have found our primary name or a name belonging
+ * to another device.
+ */
+ if (name_node == dev->name_node || name_node->dev != dev)
+ return -EINVAL;
+
__netdev_name_node_alt_destroy(name_node);

return 0;

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