bgpd: Prevent use after free (backport #14017) #14031
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When running bgp_always_compare_med, I am frequently seeing a crash After running with valgrind I am seeing this and a invalid write immediately after this as well. ==311743== Invalid read of size 2 ==311743== at 0x4992421: route_map_counter_decrement (routemap.c:3308) ==311743== by 0x35664D: peer_route_map_unset (bgpd.c:7259) ==311743== by 0x306546: peer_route_map_unset_vty (bgp_vty.c:8037) ==311743== by 0x3066AC: no_neighbor_route_map (bgp_vty.c:8081) ==311743== by 0x49078DE: cmd_execute_command_real (command.c:990) ==311743== by 0x4907A63: cmd_execute_command (command.c:1050) ==311743== by 0x490801F: cmd_execute (command.c:1217) ==311743== by 0x49C5535: vty_command (vty.c:551) ==311743== by 0x49C7459: vty_execute (vty.c:1314) ==311743== by 0x49C97D1: vtysh_read (vty.c:2223) ==311743== by 0x49BE5E2: event_call (event.c:1995) ==311743== by 0x494786C: frr_run (libfrr.c:1204) ==311743== by 0x1F7655: main (bgp_main.c:505) ==311743== Address 0x9ec2180 is 64 bytes inside a block of size 120 free'd ==311743== at 0x484B27F: free (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so) ==311743== by 0x495A1BA: qfree (memory.c:130) ==311743== by 0x498D412: route_map_free_map (routemap.c:748) ==311743== by 0x498D176: route_map_add (routemap.c:672) ==311743== by 0x498D79B: route_map_get (routemap.c:857) ==311743== by 0x499C256: lib_route_map_create (routemap_northbound.c:102) ==311743== by 0x49702D8: nb_callback_create (northbound.c:1234) ==311743== by 0x497107F: nb_callback_configuration (northbound.c:1578) ==311743== by 0x4971693: nb_transaction_process (northbound.c:1709) ==311743== by 0x496FCF4: nb_candidate_commit_apply (northbound.c:1103) ==311743== by 0x496FE4E: nb_candidate_commit (northbound.c:1136) ==311743== by 0x497798F: nb_cli_classic_commit (northbound_cli.c:49) ==311743== by 0x4977B4F: nb_cli_pending_commit_check (northbound_cli.c:88) ==311743== by 0x49078C1: cmd_execute_command_real (command.c:987) ==311743== by 0x4907B44: cmd_execute_command (command.c:1068) ==311743== by 0x490801F: cmd_execute (command.c:1217) ==311743== by 0x49C5535: vty_command (vty.c:551) ==311743== by 0x49C7459: vty_execute (vty.c:1314) ==311743== by 0x49C97D1: vtysh_read (vty.c:2223) ==311743== by 0x49BE5E2: event_call (event.c:1995) ==311743== by 0x494786C: frr_run (libfrr.c:1204) ==311743== by 0x1F7655: main (bgp_main.c:505) ==311743== Block was alloc'd at ==311743== at 0x484DA83: calloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so) ==311743== by 0x495A068: qcalloc (memory.c:105) ==311743== by 0x498D0C8: route_map_new (routemap.c:646) ==311743== by 0x498D128: route_map_add (routemap.c:658) ==311743== by 0x498D79B: route_map_get (routemap.c:857) ==311743== by 0x499C256: lib_route_map_create (routemap_northbound.c:102) ==311743== by 0x49702D8: nb_callback_create (northbound.c:1234) ==311743== by 0x497107F: nb_callback_configuration (northbound.c:1578) ==311743== by 0x4971693: nb_transaction_process (northbound.c:1709) ==311743== by 0x496FCF4: nb_candidate_commit_apply (northbound.c:1103) ==311743== by 0x496FE4E: nb_candidate_commit (northbound.c:1136) ==311743== by 0x497798F: nb_cli_classic_commit (northbound_cli.c:49) ==311743== by 0x4977B4F: nb_cli_pending_commit_check (northbound_cli.c:88) ==311743== by 0x49078C1: cmd_execute_command_real (command.c:987) ==311743== by 0x4907B44: cmd_execute_command (command.c:1068) ==311743== by 0x490801F: cmd_execute (command.c:1217) ==311743== by 0x49C5535: vty_command (vty.c:551) ==311743== by 0x49C7459: vty_execute (vty.c:1314) ==311743== by 0x49C97D1: vtysh_read (vty.c:2223) ==311743== by 0x49BE5E2: event_call (event.c:1995) ==311743== by 0x494786C: frr_run (libfrr.c:1204) Effectively the route_map that is being stored has been freed already but we have not cleaned up properly yet. Go through and clean the code up by ensuring that the pointer actually exists instead of trusting it does when doing the decrement operation. Signed-off-by: Donald Sharp <sharpd@nvidia.com> (cherry picked from commit 2ba2c28)
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This is an automatic backport of pull request #14017 done by Mergify.
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