ASAN detecting heap-use-after free but empty stack

[hharshith15]

Hi ,
I am using asan on CLANG 5.0 on Freebsd it is able to detect heap-use-after-free only when I disable optimisation but no stack trace . Below is the output . And I also see some CHECK failed . . Seems to be the problem with unwinder ,tried with fast_unwind_on_fatal=0 but the stack didn't point to valid function calls . Used -fno-omit-frame-pointer as well . Since we are building our custom toolchain , please point to patch if any that can help overcome this issue .
Please help me through.

=================================================================
==52036==ERROR: AddressSanitizer: heap-use-after-free on address 0x602000000075 at pc
sp 0x7fffffffe7f8
READ of size 1 at 0x602000000075 thread T16777215

0x602000000075 is located 5 bytes inside of 10-byte region [0x602000000070,0x60200000007a)
==52036==AddressSanitizer CHECK failed: ../compiler-t/lib/asan/asan_descriptions.cc:176
"((id)) != (0)" (0x0, 0x0)
#0 0x5b1a76 (/var/tmp/abcd+0x5b1a76)
#1 0x5c602f (/var/tmp/abcd+0x5c602f)
#2 0x552e60 (/var/tmp/abcd+0x552e60)
#3 0x555ccf (/var/tmp/abcd+0x555ccf)
#4 0x5af2a1 (/var/tmp/abcd+0x5af2a1)
#5 0x5aec81 (/var/tmp/abcd+0x5aec81)
#6 0x5af88a (/var/tmp/abcd+0x5af88a)
#7 0x68836c (/var/tmp/abcd+0x68836c)
#8 0x688705 (/var/tmp/abcd+0x688705)
#9 0xb21c7b (/var/tmp/abcd+0xb21c7b)
#10 0x54b28e (/var/tmp/abcd+0x54b28e)
#11 0x802d7efff ()

Corresponding addr2line
>addr2line -e abcd -a 0x5b1a76 0x5c602f 0x552e60 0x555ccf 0x5af2a1 0x5aec81 0x5af88a 0x68836c 0x688705 0xb21c7b 0x54b28e 0x802d7efff
0x00000000005b1a76
../compiler-rt/lib/asan/asan_rtl.cc:69
0x00000000005c602f
../compiler-rt/lib/sanitizer_common/sanitizer_termination.cc:79
0x0000000000552e60
../compiler-rt/lib/asan/asan_descriptions.cc:176
0x0000000000555ccf
../compiler-rt/lib/asan/asan_errors.cc:508
0x00000000005af2a1
../compiler-rt/lib/asan/asan_report.cc:177
0x00000000005aec81
../compiler-rt/lib/asan/asan_report.cc:421
0x00000000005af88a
../compiler-rt/lib/asan/asan_rtl.cc:131
0x000000000068836c

Thanks
Harshith H