From b318b631fa674a470f01118c7bb5a7adc7e5e743 Mon Sep 17 00:00:00 2001 From: Donald Sharp Date: Wed, 25 Nov 2020 07:36:43 -0500 Subject: [PATCH] ldpd: Prevent usage after free We are using data after it has been freed and handed back to the OS. Address Sanitizer output: error 23-Nov-2020 18:53:57 ERROR: AddressSanitizer: heap-use-after-free on address 0x631000024838 at pc 0x55f825998f58 bp 0x7fffa5b0f5b0 sp 0x7fffa5b0f5a0 error 23-Nov-2020 18:53:57 READ of size 4 at 0x631000024838 thread T0 error 23-Nov-2020 18:53:57 #0 0x55f825998f57 in lde_imsg_compose_parent_sync ldpd/lde.c:226 error 23-Nov-2020 18:53:57 #1 0x55f8259ca9ed in vlog ldpd/log.c:48 error 23-Nov-2020 18:53:57 #2 0x55f8259cb1c8 in log_info ldpd/log.c:102 error 23-Nov-2020 18:53:57 #3 0x55f82599e841 in lde_shutdown ldpd/lde.c:208 error 23-Nov-2020 18:53:57 #4 0x55f8259a2703 in lde_dispatch_parent ldpd/lde.c:666 error 23-Nov-2020 18:53:57 #5 0x55f825ac3815 in thread_call lib/thread.c:1681 error 23-Nov-2020 18:53:57 #6 0x55f825998d5e in lde ldpd/lde.c:160 error 23-Nov-2020 18:53:57 #7 0x55f82598a289 in main ldpd/ldpd.c:320 error 23-Nov-2020 18:53:57 #8 0x7fe3f749db96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96) error 23-Nov-2020 18:53:57 #9 0x55f825982579 in _start (/usr/lib/frr/ldpd+0xb3579) error 23-Nov-2020 18:53:57 error 23-Nov-2020 18:53:57 0x631000024838 is located 65592 bytes inside of 65632-byte region [0x631000014800,0x631000024860) error 23-Nov-2020 18:53:57 freed by thread T0 here: error 23-Nov-2020 18:53:57 #0 0x7fe3f8a4d7a8 in __interceptor_free (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xde7a8) error 23-Nov-2020 18:53:57 #1 0x55f82599e830 in lde_shutdown ldpd/lde.c:206 error 23-Nov-2020 18:53:57 #2 0x55f8259a2703 in lde_dispatch_parent ldpd/lde.c:666 error 23-Nov-2020 18:53:57 #3 0x55f825ac3815 in thread_call lib/thread.c:1681 error 23-Nov-2020 18:53:57 #4 0x55f825998d5e in lde ldpd/lde.c:160 error 23-Nov-2020 18:53:57 #5 0x55f82598a289 in main ldpd/ldpd.c:320 error 23-Nov-2020 18:53:57 #6 0x7fe3f749db96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96) error 23-Nov-2020 18:53:57 error 23-Nov-2020 18:53:57 previously allocated by thread T0 here: error 23-Nov-2020 18:53:57 #0 0x7fe3f8a4dd28 in __interceptor_calloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xded28) error 23-Nov-2020 18:53:57 #1 0x55f825998cb7 in lde ldpd/lde.c:151 error 23-Nov-2020 18:53:57 #2 0x55f82598a289 in main ldpd/ldpd.c:320 error 23-Nov-2020 18:53:57 #3 0x7fe3f749db96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96) error 23-Nov-2020 18:53:57 The fix is to put this in global space. Signed-off-by: Donald Sharp --- ldpd/lde.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/ldpd/lde.c b/ldpd/lde.c index df64f908ead1..a1f4530ad7b2 100644 --- a/ldpd/lde.c +++ b/ldpd/lde.c @@ -73,6 +73,7 @@ struct ldpd_conf *ldeconf; struct nbr_tree lde_nbrs = RB_INITIALIZER(&lde_nbrs); static struct imsgev *iev_ldpe; +static struct imsgev iev_main_sync_data; static struct imsgev *iev_main, *iev_main_sync; /* lde privileges */ @@ -148,8 +149,8 @@ lde(void) &iev_main->ev_read); iev_main->handler_write = ldp_write_handler; - if ((iev_main_sync = calloc(1, sizeof(struct imsgev))) == NULL) - fatal(NULL); + memset(&iev_main_sync_data, 0, sizeof(iev_main_sync_data)); + iev_main_sync = &iev_main_sync_data; imsg_init(&iev_main_sync->ibuf, LDPD_FD_SYNC); /* create base configuration */ @@ -203,7 +204,6 @@ lde_shutdown(void) if (iev_ldpe) free(iev_ldpe); free(iev_main); - free(iev_main_sync); log_info("label decision engine exiting");