On 07/09/2016 07:23 PM, Andy Gospodarek wrote:
On Sat, Jul 09, 2016 at 12:00:15PM +0300, Julian Anastasov wrote:
Vegard Nossum is reporting for a crash in fib_dump_info (fib_nhs==1)
when nh_dev = NULL. Problem happens when RTNH_F_LINKDOWN is
provided from user space for routes that do not use the flag,
catched with netlink fuzzer.
Can you also include the panic log in the changelog or at a minimum post
it here?
Pid: 50, comm: netlink.exe Not tainted 4.7.0-rc5+
RIP: 0033:[<00000000602b3d18>]
RSP: 0000000062623890 EFLAGS: 00010202
RAX: 0000000000000000 RBX: 000000006261b800 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000024 RDI: 000000006245ba00
RBP: 00000000626238f0 R08: 000000000000029c R09: 0000000000000000
R10: 0000000062468038 R11: 000000006245ba00 R12: 000000006245ba00
R13: 00000000625f96c0 R14: 00000000601e16f0 R15: 0000000000000000
Kernel panic - not syncing: Kernel mode fault at addr 0x2e0, ip 0x602b3d18
CPU: 0 PID: 50 Comm: netlink.exe Not tainted 4.7.0-rc5+ #581
Stack:
626238f0 960226a02 00000400 000000fe
62623910 600afca7 62623970 62623a48
62468038 00000018 00000000 00000000
Call Trace:
[<602b3e93>] rtmsg_fib+0xd3/0x190
[<602b6680>] fib_table_insert+0x260/0x500
[<602b0e5d>] inet_rtm_newroute+0x4d/0x60
[<60250def>] rtnetlink_rcv_msg+0x8f/0x270
[<60267079>] netlink_rcv_skb+0xc9/0xe0
[<60250d4b>] rtnetlink_rcv+0x3b/0x50
[<60265400>] netlink_unicast+0x1a0/0x2c0
[<60265e47>] netlink_sendmsg+0x3f7/0x470
[<6021dc9a>] sock_sendmsg+0x3a/0x90
[<6021e0d0>] ___sys_sendmsg+0x300/0x360
[<6021fa64>] __sys_sendmsg+0x54/0xa0
[<6021fac0>] SyS_sendmsg+0x10/0x20
[<6001ea68>] handle_syscall+0x88/0x90
[<600295fd>] userspace+0x3fd/0x500
[<6001ac55>] fork_handler+0x85/0x90
$ addr2line -e vmlinux -i 0x602b3d18
include/linux/inetdevice.h:222
net/ipv4/fib_semantics.c:1264
220 static inline struct in_device *__in_dev_get_rtnl(const struct
net_device *dev)
221 {
222 return rtnl_dereference(dev->ip_ptr);
223 }
1263 if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
1264 in_dev = __in_dev_get_rtnl(fi->fib_nh->nh_dev);
1265 if (in_dev &&
RTNH_F_LINKDOWN should be used only for link routes, not for
local routes or for routes with error code. Do not complicate
fast path with more checks, reject the flag early when configured
for incompatible routes.
Did the netlink fuzzer (trinity?) happen to check any of the other flags
(liks RTNH_F_DEAD) that are normally set by the kernel but could be
problematic when send down from userspace?
I honestly don't know -- the fuzzer (based on AFL) doesn't know anything
about netlink in particular, so if it passed/tested any other flags it
was by chance and not by design.
Vegard
