LTTng » LTTng-UST

Actually, the splat above seems to be related to jhash.h.

Which is a documented limitation in jhash.h:

• "k²&0xffffff" actually reads beyond the end of the string, but
• then masks off the part it's not allowed to read. Because the
• string is aligned, the masked-off tail is in the same word as the
• rest of the string. Every machine with memory protection I've seen
• does it on word boundaries, so is OK with this. But VALGRIND will
• still catch it and complain. The masking trick does make the hash
• noticably faster for short strings (like English words).

After fixing jhash.h, here is the tracepoint splat:

=================================================================
16513ERROR: AddressSanitizer: global-buffer-overflow on address 0x7f65d99412c8 at pc 0x7f65d92db469 bp 0x7fff1c2be8b0 sp 0x7fff1c2be8a8
READ of size 8 at 0x7f65d99412c8 thread T0
#0 0x7f65d92db468 in lib_register_callsites /home/efficios/git/lttng-ust/liblttng-ust/tracepoint.c:547:8
#1 0x7f65d92daa91 in tracepoint_register_lib /home/efficios/git/lttng-ust/liblttng-ust/tracepoint.c:903:2
#2 0x7f65d961e9ee in _tracepoints_ptrs_init /home/efficios/git/lttng-ust/liblttng-ust/../include/lttng/tracepoint.h:485:3
#3 0x7f65d962052d in lttng_ust_statedump_init /home/efficios/git/lttng-ust/liblttng-ust/lttng-ust-statedump.c:645:2
#4 0x7f65d9587a85 in lttng_ust_init /home/efficios/git/lttng-ust/liblttng-ust/lttng-ust-comm.c:1846:2
#5 0x7f65d995d732 (/lib64/ld-linux-x86-64.so.2+0x10732)
#6 0x7f65d994e0c9 (/lib64/ld-linux-x86-64.so.2+0x10c9)

0x7f65d99412c8 is located 56 bytes to the left of global variable '__tracepoint_ptr_lttng_ust_lib___build_id' defined in './ust_lib.h:55:1' (0x7f65d9941300) of size 8
0x7f65d99412c8 is located 0 bytes to the right of global variable '__tracepoint_ptr_lttng_ust_lib___load' defined in './ust_lib.h:42:1' (0x7f65d99412c0) of size 8
SUMMARY: AddressSanitizer: global-buffer-overflow /home/efficios/git/lttng-ust/liblttng-ust/tracepoint.c:547:8 in lib_register_callsites
Shadow bytes around the buggy address:
0x0fed3b320200: f9 f9 f9 f9 00 00 00 00 00 00 00 f9 f9 f9 f9 f9
0x0fed3b320210: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 00 00 00
0x0fed3b320220: 00 00 00 f9 f9 f9 f9 f9 00 00 00 00 00 00 00 f9
0x0fed3b320230: f9 f9 f9 f9 00 00 00 00 00 00 00 f9 f9 f9 f9 f9
0x0fed3b320240: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 00 00 00
=>0x0fed3b320250: 00 00 00 f9 f9 f9 f9 f9 00[f9]f9 f9 f9 f9 f9 f9
0x0fed3b320260: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
0x0fed3b320270: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
0x0fed3b320280: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
0x0fed3b320290: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
0x0fed3b3202a0: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
16513ABORTING