bgpd: When creating extra from stack ensure it is zero'ed out #5131
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Possible fix for #5025 Please note this is a continuation of an already existing pattern in the code |
💚 Basic BGPD CI results: SUCCESS, 0 tests failedResults table
For details, please contact louberger |
Continuous Integration Result: SUCCESSFULCongratulations, this patch passed basic tests Tested-by: NetDEF / OpenSourceRouting.org CI System CI System Testrun URL: https://ci1.netdef.org/browse/FRR-FRRPULLREQ-9186/ This is a comment from an automated CI system. CLANG Static Analyzer Summary
No Changes in Static Analysis warnings compared to base1 Static Analyzer issues remaining.See details at |
BGP code assumes that the extra data is zero'ed out. Ensure that we are not leaving any situation that the data on the stack is actually all 0's when we pass it around as a pointer later. Please note in issue FRRouting#5025, Lou reported a different valgrind issue, which is not the same issue: ==7313== Conditional jump or move depends on uninitialised value(s) ==7313== at 0x181F9F: subgroup_announce_check (bgp_route.c:1555) ==7313== by 0x1A112B: subgroup_announce_table (bgp_updgrp_adv.c:641) ==7313== by 0x1A1340: subgroup_announce_route (bgp_updgrp_adv.c:704) ==7313== by 0x1A13E3: subgroup_coalesce_timer (bgp_updgrp_adv.c:331) ==7313== by 0x4EBA615: thread_call (thread.c:1531) ==7313== by 0x4E8AC37: frr_run (libfrr.c:1052) ==7313== by 0x1429E0: main (bgp_main.c:486) ==7313== ==7313== Conditional jump or move depends on uninitialised value(s) ==7313== at 0x201C0E: rfapi_vty_out_vncinfo (rfapi_vty.c:429) ==7313== by 0x18D0D6: route_vty_out (bgp_route.c:7481) ==7313== by 0x18DD76: bgp_show_table (bgp_route.c:9365) ==7313== by 0x1930C4: bgp_show_table_rd (bgp_route.c:9471) ==7313== by 0x1932A3: bgp_show (bgp_route.c:9510) ==7313== by 0x193E68: show_ip_bgp_json (bgp_route.c:10284) ==7313== by 0x4E6D024: cmd_execute_command_real.isra.2 (command.c:1072) ==7313== by 0x4E6F51E: cmd_execute_command (command.c:1131) ==7313== by 0x4E6F686: cmd_execute (command.c:1285) ==7313== by 0x4EBF9C4: vty_command (vty.c:516) ==7313== by 0x4EBFB9F: vty_execute (vty.c:1285) ==7313== by 0x4EC250F: vtysh_read (vty.c:2119) ==7313== that is causing the actual crash. Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
We are passing around the created rd, Just make sure that the data is zero'ed out. Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
Our Address Sanitizer CI is finding this issue: error 09-Oct-2019 19:28:33 r4: bgpd triggered an exception by AddressSanitizer error 09-Oct-2019 19:28:33 ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffdd425b060 at pc 0x00000068575f bp 0x7ffdd4258550 sp 0x7ffdd4258540 error 09-Oct-2019 19:28:33 READ of size 1 at 0x7ffdd425b060 thread T0 error 09-Oct-2019 19:28:33 #0 0x68575e in prefix_cmp lib/prefix.c:776 error 09-Oct-2019 19:28:33 #1 0x5889f5 in rfapiItBiIndexSearch bgpd/rfapi/rfapi_import.c:2230 error 09-Oct-2019 19:28:33 #2 0x5889f5 in rfapiBgpInfoFilteredImportVPN bgpd/rfapi/rfapi_import.c:3520 error 09-Oct-2019 19:28:33 #3 0x58b909 in rfapiProcessWithdraw bgpd/rfapi/rfapi_import.c:4071 error 09-Oct-2019 19:28:33 #4 0x4c459b in bgp_withdraw bgpd/bgp_route.c:3736 error 09-Oct-2019 19:28:33 #5 0x484122 in bgp_nlri_parse_vpn bgpd/bgp_mplsvpn.c:237 error 09-Oct-2019 19:28:33 #6 0x497f52 in bgp_nlri_parse bgpd/bgp_packet.c:315 error 09-Oct-2019 19:28:33 #7 0x49d06d in bgp_update_receive bgpd/bgp_packet.c:1598 error 09-Oct-2019 19:28:33 #8 0x49d06d in bgp_process_packet bgpd/bgp_packet.c:2274 error 09-Oct-2019 19:28:33 #9 0x6b9f54 in thread_call lib/thread.c:1531 error 09-Oct-2019 19:28:33 #10 0x657037 in frr_run lib/libfrr.c:1052 error 09-Oct-2019 19:28:33 #11 0x42d268 in main bgpd/bgp_main.c:486 error 09-Oct-2019 19:28:33 #12 0x7f806032482f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f) error 09-Oct-2019 19:28:33 #13 0x42bcc8 in _start (/usr/lib/frr/bgpd+0x42bcc8) error 09-Oct-2019 19:28:33 error 09-Oct-2019 19:28:33 Address 0x7ffdd425b060 is located in stack of thread T0 at offset 240 in frame error 09-Oct-2019 19:28:33 #0 0x483945 in bgp_nlri_parse_vpn bgpd/bgp_mplsvpn.c:103 error 09-Oct-2019 19:28:33 error 09-Oct-2019 19:28:33 This frame has 5 object(s): error 09-Oct-2019 19:28:33 [32, 36) 'label' error 09-Oct-2019 19:28:33 [96, 108) 'rd_as' error 09-Oct-2019 19:28:33 [160, 172) 'rd_ip' error 09-Oct-2019 19:28:33 [224, 240) 'prd' <== Memory access at offset 240 overflows this variable error 09-Oct-2019 19:28:33 [288, 336) 'p' error 09-Oct-2019 19:28:33 HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext error 09-Oct-2019 19:28:33 (longjmp and C++ exceptions *are* supported) error 09-Oct-2019 19:28:33 SUMMARY: AddressSanitizer: stack-buffer-overflow lib/prefix.c:776 prefix_cmp error 09-Oct-2019 19:28:33 Shadow bytes around the buggy address: error 09-Oct-2019 19:28:33 0x10003a8435b0: 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 00 error 09-Oct-2019 19:28:33 0x10003a8435c0: 00 00 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3 f3 error 09-Oct-2019 19:28:33 0x10003a8435d0: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 error 09-Oct-2019 19:28:33 0x10003a8435e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 error 09-Oct-2019 19:28:33 0x10003a8435f0: f1 f1 04 f4 f4 f4 f2 f2 f2 f2 00 04 f4 f4 f2 f2 error 09-Oct-2019 19:28:33 =>0x10003a843600: f2 f2 00 04 f4 f4 f2 f2 f2 f2 00 00[f4]f4 f2 f2 error 09-Oct-2019 19:28:33 0x10003a843610: f2 f2 00 00 00 00 00 00 f4 f4 f3 f3 f3 f3 00 00 error 09-Oct-2019 19:28:33 0x10003a843620: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 error 09-Oct-2019 19:28:33 0x10003a843630: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 02 f4 error 09-Oct-2019 19:28:33 0x10003a843640: f4 f4 f2 f2 f2 f2 04 f4 f4 f4 f2 f2 f2 f2 00 00 error 09-Oct-2019 19:28:33 0x10003a843650: f4 f4 f2 f2 f2 f2 00 00 00 00 f2 f2 f2 f2 00 00 error 09-Oct-2019 19:28:33 Shadow byte legend (one shadow byte represents 8 application bytes): error 09-Oct-2019 19:28:33 Addressable: 00 error 09-Oct-2019 19:28:33 Partially addressable: 01 02 03 04 05 06 07 error 09-Oct-2019 19:28:33 Heap left redzone: fa error 09-Oct-2019 19:28:33 Heap right redzone: fb error 09-Oct-2019 19:28:33 Freed heap region: fd error 09-Oct-2019 19:28:33 Stack left redzone: f1 error 09-Oct-2019 19:28:33 Stack mid redzone: f2 error 09-Oct-2019 19:28:33 Stack right redzone: f3 error 09-Oct-2019 19:28:33 Stack partial redzone: f4 error 09-Oct-2019 19:28:33 Stack after return: f5 error 09-Oct-2019 19:28:33 Stack use after scope: f8 error 09-Oct-2019 19:28:33 Global redzone: f9 error 09-Oct-2019 19:28:33 Global init order: f6 error 09-Oct-2019 19:28:33 Poisoned by user: f7 error 09-Oct-2019 19:28:33 Container overflow: fc error 09-Oct-2019 19:28:33 Array cookie: ac error 09-Oct-2019 19:28:33 Intra object redzone: bb error 09-Oct-2019 19:28:33 ASan internal: fe error 09-Oct-2019 19:28:36 r3: Daemon bgpd not running This is the result of this code pattern in rfapi/rfapi_import.c: prefix_cmp((struct prefix *)&bpi_result->extra->vnc.import.rd, (struct prefix *)prd)) Effectively prd or vnc.import.rd are `struct prefix_rd` which are being typecast to a `struct prefix`. Not a big deal except commit 1315d74 modified the prefix_cmp function to allow for a sorted prefix_cmp. In prefix_cmp we were looking at the offset and shift. In the case of vnc we were passing a prefix length of 64 which is the exact length of the remaining data structure for struct prefix_rd. So we calculated a offset of 8 and a shift of 0. The data structures for the prefix portion happened to be equal to 64 bits of data. So we checked that with the memcmp got a 0 and promptly read off the end of the data structure for the numcmp. The fix is if shift is 0 that means thei the memcmp has checked everything and there is nothing to do. Please note: We will still crash if we set the prefixlen > then ~312 bits currently( ie if the prefixlen specifies a bit length longer than the prefix length ). I do not think there is anything to do here( nor am I sure how to correct this either ) as that we are going to have some severe problems when we muck up the prefixlen. Fixes: FRRouting#5025 Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
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💚 Basic BGPD CI results: SUCCESS, 0 tests failedResults table
For details, please contact louberger |
Continuous Integration Result: SUCCESSFULCongratulations, this patch passed basic tests Tested-by: NetDEF / OpenSourceRouting.org CI System CI System Testrun URL: https://ci1.netdef.org/browse/FRR-FRRPULLREQ-9193/ This is a comment from an automated CI system. CLANG Static Analyzer Summary
No Changes in Static Analysis warnings compared to base1 Static Analyzer issues remaining.See details at |
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BGP code assumes that the extra data is zero'ed out. Ensure that we
are not leaving any situation that the data on the stack is actually all
0's when we pass it around as a pointer later.
Signed-off-by: Donald Sharp sharpd@cumulusnetworks.com