[7.5]zebra: Fix use after free in debug path

[donaldsharp]

When zebra is running with debugs turned on there
is a use after free reported by the address sanitizer:

2020/10/16 12:58:02 ZEBRA: rib_delnode: (0:254):4.5.6.16/32: rn 0x60b000026f20, re 0x6080000131a0, removing
2020/10/16 12:58:02 ZEBRA: rib_meta_queue_add: (0:254):4.5.6.16/32: queued rn 0x60b000026f20 into sub-queue 3

==3101430==ERROR: AddressSanitizer: heap-use-after-free on address 0x608000011d28 at pc 0x555555705ab6 bp 0x7fffffffdab0 sp 0x7fffffffdaa8
READ of size 8 at 0x608000011d28 thread T0
#0 0x555555705ab5 in re_list_const_first zebra/rib.h:222
#1 0x555555705b54 in re_list_first zebra/rib.h:222
#2 0x555555711a4f in process_subq_route zebra/zebra_rib.c:2248
#3 0x555555711d2e in process_subq zebra/zebra_rib.c:2286
#4 0x555555711ec7 in meta_queue_process zebra/zebra_rib.c:2320
#5 0x7ffff74701f7 in work_queue_run lib/workqueue.c:291
#6 0x7ffff7450e9c in thread_call lib/thread.c:1581
#7 0x7ffff738eaf7 in frr_run lib/libfrr.c:1099
#8 0x55555561a578 in main zebra/main.c:455
#9 0x7ffff7079cc9 in __libc_start_main ../csu/libc-start.c:308
#10 0x5555555e3429 in _start (/usr/lib/frr/zebra+0x8f429)
0x608000011d28 is located 8 bytes inside of 88-byte region [0x608000011d20,0x608000011d78)
freed by thread T0 here:
#0 0x7ffff768bb6f in __interceptor_free (/lib/x86_64-linux-gnu/libasan.so.6+0xa9b6f)
#1 0x7ffff739ccad in qfree lib/memory.c:129
#2 0x555555709ee4 in rib_gc_dest zebra/zebra_rib.c:746
#3 0x55555570ca76 in rib_process zebra/zebra_rib.c:1240
#4 0x555555711a05 in process_subq_route zebra/zebra_rib.c:2245
#5 0x555555711d2e in process_subq zebra/zebra_rib.c:2286
#6 0x555555711ec7 in meta_queue_process zebra/zebra_rib.c:2320
#7 0x7ffff74701f7 in work_queue_run lib/workqueue.c:291
#8 0x7ffff7450e9c in thread_call lib/thread.c:1581
#9 0x7ffff738eaf7 in frr_run lib/libfrr.c:1099
#10 0x55555561a578 in main zebra/main.c:455
#11 0x7ffff7079cc9 in __libc_start_main ../csu/libc-start.c:308
previously allocated by thread T0 here:
#0 0x7ffff768c037 in calloc (/lib/x86_64-linux-gnu/libasan.so.6+0xaa037)
#1 0x7ffff739cb98 in qcalloc lib/memory.c:110
#2 0x555555712ace in zebra_rib_create_dest zebra/zebra_rib.c:2515
#3 0x555555712c6c in rib_link zebra/zebra_rib.c:2576
#4 0x555555712faa in rib_addnode zebra/zebra_rib.c:2607
#5 0x555555715bf0 in rib_add_multipath_nhe zebra/zebra_rib.c:3012
#6 0x555555715f56 in rib_add_multipath zebra/zebra_rib.c:3049
#7 0x55555571788b in rib_add zebra/zebra_rib.c:3327
#8 0x5555555e584a in connected_up zebra/connected.c:254
#9 0x5555555e42ff in connected_announce zebra/connected.c:94
#10 0x5555555e4fd3 in connected_update zebra/connected.c:195
#11 0x5555555e61ad in connected_add_ipv4 zebra/connected.c:340
#12 0x5555555f26f5 in netlink_interface_addr zebra/if_netlink.c:1213
#13 0x55555560f756 in netlink_information_fetch zebra/kernel_netlink.c:350
#14 0x555555612e49 in netlink_parse_info zebra/kernel_netlink.c:941
#15 0x55555560f9f1 in kernel_read zebra/kernel_netlink.c:402
#16 0x7ffff7450e9c in thread_call lib/thread.c:1581
#17 0x7ffff738eaf7 in frr_run lib/libfrr.c:1099
#18 0x55555561a578 in main zebra/main.c:455
#19 0x7ffff7079cc9 in __libc_start_main ../csu/libc-start.c:308
SUMMARY: AddressSanitizer: heap-use-after-free zebra/rib.h:222 in re_list_const_first

This is happening because we are using the dest pointer after a call into
rib_gc_dest. In process_subq_route, we call rib_process() and if the
dest is deleted dest pointer is now garbage. We must reload the
dest pointer in this case.

Signed-off-by: Donald Sharp sharpd@nvidia.com

[NetDEF-CI]

Continuous Integration Result: SUCCESSFUL

Congratulations, this patch passed basic tests

Tested-by: NetDEF / OpenSourceRouting.org CI System

CI System Testrun URL: https://ci1.netdef.org/browse/FRR-FRRPULLREQ-14804/

This is a comment from an automated CI system.
For questions and feedback in regards to this CI system, please feel free to email
Martin Winter - mwinter (at) opensourcerouting.org.

Warnings Generated during build:

Debian 10 amd64 build: Successful with additional warnings

Debian Package lintian failed for Debian 10 amd64 build:
(see full package build log at https://ci1.netdef.org/browse/FRR-FRRPULLREQ-14804/artifact/DEB10BUILD/ErrorLog/log_lintian.txt)

W: frr source: pkg-js-tools-test-is-missing
W: frr source: newer-standards-version 4.4.1 (current is 4.3.0)
W: frr source: pkg-js-tools-test-is-missing
W: frr source: newer-standards-version 4.4.1 (current is 4.3.0)
W: frr-doc: changelog-file-missing-explicit-entry 6.0-2 -> 7.5-dev-20201016-00-g947097edd-0 (missing) -> 7.5-dev-20201016-00-g947097edd-0~deb10u1
W: frr: changelog-file-missing-explicit-entry 6.0-2 -> 7.5-dev-20201016-00-g947097edd-0 (missing) -> 7.5-dev-20201016-00-g947097edd-0~deb10u1
W: frr-snmp: changelog-file-missing-explicit-entry 6.0-2 -> 7.5-dev-20201016-00-g947097edd-0 (missing) -> 7.5-dev-20201016-00-g947097edd-0~deb10u1
W: frr-pythontools: changelog-file-missing-explicit-entry 6.0-2 -> 7.5-dev-20201016-00-g947097edd-0 (missing) -> 7.5-dev-20201016-00-g947097edd-0~deb10u1
W: frr-rpki-rtrlib: changelog-file-missing-explicit-entry 6.0-2 -> 7.5-dev-20201016-00-g947097edd-0 (missing) -> 7.5-dev-20201016-00-g947097edd-0~deb10u1