Fix TIPC to disallow sending to remote addresses prior to entering NET_MODE
user programs can oops the kernel by sending datagrams via AF_TIPC prior to
entering networked mode. The following backtrace has been observed:
ID: 13459 TASK: ffff810014640040 CPU: 0 COMMAND: "tipc-client"
[exception RIP: tipc_node_select_next_hop+90]
RIP: ffffffff8869d3c3 RSP: ffff81002d9a5ab8 RFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000001001001
RBP: 0000000001001001 R8: 0074736575716552 R9: 0000000000000000
R10: ffff81003fbd0680 R11: 00000000000000c8 R12: 0000000000000008
R13: 0000000000000001 R14: 0000000000000001 R15: ffff810015c6ca00
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
RIP: 0000003cbd8d49a3 RSP: 00007fffc84e0be8 RFLAGS: 00010206
RAX: 000000000000002c RBX: ffffffff8005d116 RCX: 0000000000000000
RDX: 0000000000000008 RSI: 00007fffc84e0c00 RDI: 0000000000000003
RBP: 0000000000000000 R8: 00007fffc84e0c10 R9: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffc84e0d10 R14: 0000000000000000 R15: 00007fffc84e0c30
ORIG_RAX: 000000000000002c CS: 0033 SS: 002b
What happens is that, when the tipc module in inserted it enters a standalone
node mode in which communication to its own address is allowed <0.0.0> but not
to other addresses, since the appropriate data structures have not been
allocated yet (specifically the tipc_net pointer). There is nothing stopping a
client from trying to send such a message however, and if that happens, we
attempt to dereference tipc_net.zones while the pointer is still NULL, and
explode. The fix is pretty straightforward. Since these oopses all arise from
the dereference of global pointers prior to their assignment to allocated
values, and since these allocations are small (about 2k total), lets convert
these pointers to static arrays of the appropriate size. All the accesses to
these bits consider 0/NULL to be a non match when searching, so all the lookups
still work properly, and there is no longer a chance of a bad dererence
anywhere. As a bonus, this lets us eliminate the setup/teardown routines for
those pointers, and elimnates the need to preform any locking around them to
prevent access while their being allocated/freed.
I've updated the tipc_net structure to behave this way to fix the exact reported
problem, and also fixed up the tipc_bearers and media_list arrays to fix an
obvious simmilar problem that arises from issuing tipc-config commands to
manipulate bearers/links prior to entering networked mode
I've tested this for a few hours by running the sanity tests and stress test
with the tipcutils suite, and nothing has fallen over. There have been a few
lockdep warnings, but those were there before, and can be addressed later, as
they didn't actually result in any deadlock.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Allan Stephens <allan.stephens@windriver.com>
CC: David S. Miller <davem@davemloft.net>
CC: tipc-discussion@lists.sourceforge.net
bearer.c | 37 ++++++-------------------------------
bearer.h | 2 +-
net.c | 25 ++++---------------------
3 files changed, 11 insertions(+), 53 deletions(-)
Signed-off-by: David S. Miller <davem@davemloft.net>