> On Jan 5, 2017, at 9:06 PM, Ben Pfaff <[email protected]> wrote: > > On Thu, Jan 05, 2017 at 05:45:29PM -0800, Jarno Rajahalme wrote: >> >>> On Jan 5, 2017, at 4:48 PM, Ben Pfaff <[email protected]> wrote: >>> >>> On Thu, Jan 05, 2017 at 04:03:17PM -0800, Jarno Rajahalme wrote: >>>> >>>>> On Jan 4, 2017, at 11:03 PM, Ben Pfaff <[email protected]> wrote: >>>>> >>>>> On Wed, Jan 04, 2017 at 07:21:44PM -0800, Jarno Rajahalme wrote: >>>>>> >>>>>>> On Dec 21, 2016, at 2:36 PM, Ben Pfaff <[email protected]> wrote: >>>>>>> >>>>>>> On Wed, Dec 07, 2016 at 04:49:00PM -0800, Jarno Rajahalme wrote: >>>>>>> I'd be more comfortable if nx_stack_pop() had assertions to check for >>>>>>> underflow. >>>>>> >>>>>> I don’t think OVS should assert fail if controller issues one pop >>>>>> too many? Do you mean that current users of nx_stack_pop() do not >>>>>> check for NULL return? I had a look and think that setting “*bytes” >>>>>> to zero when returning NULL should be enough for all users. >>>>> >>>>> It appears to me that if stack->size is greater than 0 but less than the >>>>> number of bytes indicated by its last byte, then it will corrupt the >>>>> ofpbuf size and that this will later cause some kind of failure that >>>>> will be harder to debug than an assertion failure. >>>>> >>>> >>>> OK, now i got it. This is just to guard against (future) bugs in OVS >>>> itself. >>> >>> Yes. >>> >>>>>>> In ofputil_decode_packet_in_private(), it's probably worth checking the >>>>>>> format of the stack we pull from the payload, since a badly formatted >>>>>>> stack can segfault us (if we leave out assertions) or assert-fail us (if >>>>>>> we include them). >>>>>>> >>>>>> >>>>>> What do you mean with badly formatted stack? Zero-sized property? IMO >>>>>> even that would be properly pushed and popped from the stack, storing >>>>>> only the length (of zero) in the stack. >>>>> >>>>> I mean that if the property contains, for example, a single byte with >>>>> value 0xff, then it's badly formatted because we can pop off a length >>>>> (255) but then popping off that number of bytes will underflow. >>>> >>>> I did not change the encoding of the stack as properties, so each >>>> value in the stack is still encoded as a separate property, where the >>>> (aligned) value length is used as the property length. >>> >>> I guess I forgot that. >>> >>> Thanks, that's fine then. >>> >>>> ofpprop_pull() does the length checking for the properties and the >>>> current code in ofputil_decode_packet_in_private() assert fails on any >>>> error, which is not good, as a controller bug would crash OVS? >>> >>> That's bad. Maybe the fix is as simple as this, though. >>> >>> diff --git a/lib/ofp-util.c b/lib/ofp-util.c >>> index 156d8d2..421b9d7 100644 >>> --- a/lib/ofp-util.c >>> +++ b/lib/ofp-util.c >>> @@ -1,5 +1,5 @@ >>> /* >>> - * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 >>> Nicira, Inc. >>> + * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, >>> 2017 Nicira, Inc. >>> * >>> * Licensed under the Apache License, Version 2.0 (the "License"); >>> * you may not use this file except in compliance with the License. >>> @@ -4061,7 +4061,9 @@ ofputil_decode_packet_in_private(const struct >>> ofp_header *oh, bool loose, >>> uint64_t type; >>> >>> error = ofpprop_pull(&continuation, &payload, &type); >>> - ovs_assert(!error); >>> + if (error) { >>> + break; >>> + } >>> >>> switch (type) { >>> case NXCPT_BRIDGE: >>> @@ -4124,7 +4126,7 @@ ofputil_decode_packet_in_private(const struct >>> ofp_header *oh, bool loose, >>> ofputil_packet_in_private_destroy(pin); >>> } >>> >>> - return 0; >>> + return error; >>> } >>> >>> /* Frees data in 'pin' that is dynamically allocated by >>> >> >> I folded this in to v3. > > This bug is in 2.6, isn't it? If so then we should fix it in a separate > patch, for backporting purposes.
Right, I’ll separate it out. What is the most proper way to attribute it to you? "Suggested-by”, or something else? Jarno _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
