How to use address sanitizer?

Gratuity9629 · October 11, 2025, 4:34pm

I am using zig as my build system for my c project. I need an address sanitizer for debugging, however when i use the -fsanitize=address flag in the addCSourceFile function and try to build, I get lld-link errors like so:

error: lld-link: undefined symbol: __asan_handle_no_return
error: lld-link: undefined symbol: __asan_report_store8
... 15 more

I haven’t found any solutions for windows. Maybe I have to link against something to make this work, but I don’t exactly know.

npc1054657282 · October 11, 2025, 5:57pm

May be relevant

github.com/ziglang/zig

zig cc -fsanatize=address fails at link time on macOS

opened 02:36PM - 07 Apr 22 UTC

drfuchs

bug os-macos zig cc

### Zig Version 0.10.0-dev.1736+93e11b824 ### Steps to Reproduce zig cc -fsan…itize=address hello.c Tried on "Apple M1 Pro macOS Monterey 12.3.1" as well as "Intel Core i7 macOS Catalina 10.15.7" ### Expected Behavior Joy in Mudville ### Actual Behavior zig cc -fsanitize=address hello.c error(link): undefined reference to symbol '___asan_init' error(link): first referenced in '/Users/elided/.cache/zig/o/elided/hello.o' error(link): undefined reference to symbol '___asan_register_image_globals' error(link): first referenced in '/Users/elided/.cache/zig/o/elided/hello.o' error(link): undefined reference to symbol '___asan_unregister_image_globals' error(link): first referenced in '/Users/elided/.cache/zig/o/elided/hello.o' error(link): undefined reference to symbol '___asan_version_mismatch_check_v8' error(link): first referenced in '/Users/elided/.cache/zig/o/elided/hello.o' error: UndefinedSymbolReference (On macOS Monterey, it also first complained: warning(link): directory not found for '-L/usr/local/lib' for what that's worth.)

github.com/ziglang/zig

Zig not linking libasan or libubsan binaries by default

opened 08:30PM - 09 Jul 25 UTC

JacobHumphreys

bug

### Zig Version 0.14.1 ### Steps to Reproduce and Observed Behavior ## Descri…ption On the current release of zig, 0.14.1, it appears that zig c++ cannot properly link libasan (or libubsan) on its own. I have tested this on nixos and fedora. ## Steps to reproduce ### Verify clang versions #### Zig ``` ❯ zig c++ --version clang version 19.1.7 Target: x86_64-unknown-linux-gnu Thread model: posix InstalledDir: /nix/store/xfs50swh37h0qj78sfhsg8ppl41gi10z-zig-0.14.1/bin ``` #### Clang ``` ❯ clang --version clang version 19.1.7 Target: x86_64-unknown-linux-gnu Thread model: posix InstalledDir: /nix/store/zmk3gqm6sxgar8b84sz66wbs7kx4v2gi-clang-19.1.7/bin ``` ### Provide a file that will trigger sanitization checks #### main.cpp ``` #include <cstdio> #include <ostream> #include <iostream> int* f() { int* x = new int(); return x; } int main() { int* y = f(); delete y; std::cout << "Hello world" << *y << std::endl; return 0; } ``` ### Default behavior #### Zig ``` ❯ zig c++ -fsanitize=address ./src/main.cpp -o ./main && ./main ld.lld: error: undefined symbol: __asan_report_store4 >>> referenced by main.cpp:6 (./src/main.cpp:6) >>> /home/jacob/Documents/Projects/C++/zig-compiled/.zig-cache/o/32379ce8a6dbc65da0803f8f2d8165ba/main.o:(f()) ``` #### Clang ``` ❯ clang++ -fsanitize=address ./src/main.cpp -o ./main && ./main ================================================================= ==12262==ERROR: AddressSanitizer: heap-use-after-free on address 0x502000000010 at pc 0x55aa43e2f0d0 bp 0x7fffbdc25840 sp 0x7fffbdc25838 READ of size 4 at 0x502000000010 thread T0 #0 0x55aa43e2f0cf (/home/jacob/Documents/Projects/C++/zig-compiled/main+0x16f0cf) #1 0x7fc3db02a47d (/nix/store/cg9s562sa33k78m63njfn1rw47dp9z0i-glibc-2.40-66/lib/libc.so.6+0x2a47d) (BuildId: 295697e46737532f05317823a9a421b7e462a933) #2 0x7fc3db02a538 (/nix/store/cg9s562sa33k78m63njfn1rw47dp9z0i-glibc-2.40-66/lib/libc.so.6+0x2a538) (BuildId: 295697e46737532f05317823a9a421b7e462a933) #3 0x55aa43cec344 (/home/jacob/Documents/Projects/C++/zig-compiled/main+0x2c344) ==12262==ABORTING ``` ### Determining the location of libasan In order to test manually linking it is neccesary to determine where clang stores the libasan library. Because clang names the library libclang_rt.asan-x86_64.so, we must provide that name instead of libasan like we would with gcc. ``` ❯ clang -print-file-name=libclang_rt.asan-x86_64.so /nix/store/fmysfy9gl5d59yir4fksi29wz10maljg-clang-wrapper-19.1.7/resource-root/lib/linux/libclang_rt.asan-x86_64.so ``` ### Manually linking libasan ``` ❯ zig c++ -fsanitize=address -L/nix/store/fmysfy9gl5d59yir4fksi29wz10maljg-clang-wrapper-19.1.7/resource-root/lib/linux/ -lclang_rt.asan-x86_64 ./src/main.cpp -o ./main && ./main ================================================================= ==13117==ERROR: AddressSanitizer: heap-use-after-free on address 0x502000000010 at pc 0x0000010393a3 bp 0x7ffee48cc990 sp 0x7ffee48cc988 READ of size 4 at 0x502000000010 thread T0 #0 0x0000010393a2 (/home/jacob/Documents/Projects/C++/zig-compiled/main+0x10393a2) #1 0x7f3f72c2a4d7 (/nix/store/q4wq65gl3r8fy746v9bbwgx4gzn0r2kl-glibc-2.40-66/lib/libc.so.6+0x2a4d7) (BuildId: 3938ea5fdb2ce18cf9de6ebbd07b2ed43407cf53) #2 0x7f3f72c2a59a (/nix/store/q4wq65gl3r8fy746v9bbwgx4gzn0r2kl-glibc-2.40-66/lib/libc.so.6+0x2a59a) (BuildId: 3938ea5fdb2ce18cf9de6ebbd07b2ed43407cf53) #3 0x0000010391f4 (/home/jacob/Documents/Projects/C++/zig-compiled/main+0x10391f4) ``` ### Expected Behavior Output of zig c++ and clang++ should match and not require manual linking of libasan or libubsan libraries.