linux-toradex.git/net/tipc/name_table.c, branch v4.20-rc6

tipc: eliminate message disordering during binding table update

2018-10-23T02:29:12+00:00

We have seen the following race scenario:
1) named_distribute() builds a "bulk" message, containing a PUBLISH
   item for a certain publication. This is based on the contents of
   the binding tables's 'cluster_scope' list.
2) tipc_named_withdraw() removes the same publication from the list,
   bulds a WITHDRAW message and distributes it to all cluster nodes.
3) tipc_named_node_up(), which was calling named_distribute(), sends
   out the bulk message built under 1)
4) The WITHDRAW message arrives at the just detected node, finds
   no corresponding publication, and is dropped.
5) The PUBLISH item arrives at the same node, is added to its binding
   table, and remains there forever.

This arrival disordering was earlier taken care of by the backlog queue,
originally added for a different purpose, which was removed in the
commit referred to below, but we now need a different solution.
In this commit, we replace the rcu lock protecting the 'cluster_scope'
list with a regular RW lock which comprises even the sending of the
bulk message. This both guarantees both the list integrity and the
message sending order. We will later add a commit which cleans up
this code further.

Note that this commit needs recently added commit d3092b2efca1 ("tipc:
fix unsafe rcu locking when accessing publication list") to apply
cleanly.

Fixes: 37922ea4a310 ("tipc: permit overlapping service ranges in name table")
Reported-by: Tuong Lien Tong 
Acked-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: fix the big/little endian issue in tipc_dest

2018-08-27T22:23:31+00:00

In function tipc_dest_push, the 32bit variables 'node' and 'port'
are stored separately in uppper and lower part of 64bit 'value'.
Then this value is assigned to dst->value which is a union like:
union
{
  struct {
    u32 port;
    u32 node;
  };
  u64 value;
}
This works on little-endian machines like x86 but fails on big-endian
machines.

The fix remove the 'value' stack parameter and even the 'value'
member of the union in tipc_dest, assign the 'node' and 'port' member
directly with the input parameter to avoid the endian issue.

Fixes: a80ae5306a73 ("tipc: improve destination linked list")
Signed-off-by: Zhenbo Gao 
Acked-by: Jon Maloy 
Signed-off-by: Haiqing Bai 
Signed-off-by: David S. Miller

net: tipc: name_table: Replace GFP_ATOMIC with GFP_KERNEL in tipc_nametbl_init()

2018-07-27T20:45:15+00:00

tipc_nametbl_init() is never called in atomic context.
It calls kzalloc() with GFP_ATOMIC, which is not necessary.
GFP_ATOMIC can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai 
Signed-off-by: David S. Miller

tipc: clean up removal of binding table items

2018-05-10T19:25:45+00:00

In commit be47e41d77fb ("tipc: fix use-after-free in tipc_nametbl_stop")
we fixed a problem caused by premature release of service range items.

That fix is correct, and solved the problem. However, it doesn't address
the root of the problem, which is that we don't lookup the tipc_service
 -> service_range -> publication items in the correct hierarchical
order.

In this commit we try to make this right, and as a side effect obtain
some code simplification.

Acked-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: fix use-after-free in tipc_nametbl_stop

2018-04-18T17:48:43+00:00

When we delete a service item in tipc_nametbl_stop() we loop over
all service ranges in the service's RB tree, and for each service
range we loop over its pertaining publications while calling
tipc_service_remove_publ() for each of them.

However, tipc_service_remove_publ() has the side effect that it also
removes the comprising service range item when there are no publications
left. This leads to a "use-after-free" access when the inner loop
continues to the next iteration, since the range item holding the list
we are looping no longer exists.

We fix this by moving the delete of the service range item outside
the said function. Instead, we now let the two functions calling it
test if the list is empty and perform the removal when that is the
case.

Reported-by: syzbot+d64b64afc55660106556@syzkaller.appspotmail.com
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: fix unbalanced reference counter

2018-04-13T01:46:10+00:00

When a topology subscription is created, we may encounter (or KASAN
may provoke) a failure to create a corresponding service instance in
the binding table. Instead of letting the tipc_nametbl_subscribe()
report the failure back to the caller, the function just makes a warning
printout and returns, without incrementing the subscription reference
counter as expected by the caller.

This makes the caller believe that the subscription was successful, so
it will at a later moment try to unsubscribe the item. This involves
a sub_put() call. Since the reference counter never was incremented
in the first place, we get a premature delete of the subscription item,
followed by a "use-after-free" warning.

We fix this by adding a return value to tipc_nametbl_subscribe() and
make the caller aware of the failure to subscribe.

This bug seems to always have been around, but this fix only applies
back to the commit shown below. Given the low risk of this happening
we believe this to be sufficient.

Fixes: commit 218527fe27ad ("tipc: replace name table service range
array with rb tree")
Reported-by: syzbot+aa245f26d42b8305d157@syzkaller.appspotmail.com

Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: permit overlapping service ranges in name table

2018-04-01T02:19:52+00:00

With the new RB tree structure for service ranges it becomes possible to
solve an old problem; - we can now allow overlapping service ranges in
the table.

When inserting a new service range to the tree, we use 'lower' as primary
key, and when necessary 'upper' as secondary key.

Since there may now be multiple service ranges matching an indicated
'lower' value, we must also add the 'upper' value to the functions
used for removing publications, so that the correct, corresponding
range item can be found.

These changes guarantee that a well-formed publication/withdrawal item
from a peer node never will be rejected, and make it possible to
eliminate the problematic backlog functionality we currently have for
handling such cases.

Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: refactor name table translate function

2018-04-01T02:19:52+00:00

The function tipc_nametbl_translate() function is ugly and hard to
follow. This can be improved somewhat by introducing a stack variable
for holding the publication list to be used and re-ordering the if-
clauses for selection of algorithm.

Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: replace name table service range array with rb tree

2018-04-01T02:19:52+00:00

The current design of the binding table has an unnecessary memory
consuming and complex data structure. It aggregates the service range
items into an array, which is expanded by a factor two every time it
becomes too small to hold a new item. Furthermore, the arrays never
shrink when the number of ranges diminishes.

We now replace this array with an RB tree that is holding the range
items as tree nodes, each range directly holding a list of bindings.

This, along with a few name changes, improves both readability and
volume of the code, as well as reducing memory consumption and hopefully
improving cache hit rate.

Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: remove direct accesses to own_addr field in struct tipc_net

2018-03-23T17:12:18+00:00

As a preparation to changing the addressing structure of TIPC we replace
all direct accesses to the tipc_net::own_addr field with the function
dedicated for this, tipc_own_addr().

There are no changes to program logics in this commit.

Acked-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller