Skip to content

Commit

Permalink
ldpd: Prevent usage after free
Browse files Browse the repository at this point in the history 
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 <sharpd@nvidia.com>
  • Loading branch information
@donaldsharp
donaldsharp committed Nov 25, 2020
1 parent f286bcf commit 59c5b83
Showing 1 changed file with 3 additions and 3 deletions.
6 changes: 3 additions & 3 deletions ldpd/lde.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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");

Expand Down

0 comments on commit 59c5b83

Please sign in to comment.