GCC Address Sanitizer – identifying what produced which defect log

[Gordon McConnell <Gordon.McConnell@xxxxxxxxxxxx>]

Hi all,

We are switching from Valgrind to Asan for catching various memory related defects, mostly because of the superior speed with the Asan approach.

One area we’re currently having some difficulty with, happens when we have an executable that fires off multiple sub-processes (each of which may be the same, or a different exe – but still an address sanitized exe). We end up with a large number of defect logs, and don’t have clarity as to exactly what produced each one.

Thanks to ASAN_OPTIONS set to include the exe name and the process id, we do know which exe produced each log, but we don’t know HOW that exe was invoked.

For simplicity, consider a trivial case in which each child process is invoked as ‘foo <some_color>’ – so the child processes run as ‘foo blue’, ‘foo red’, ‘foo yellow’ etc. … but the logs are recorded as foo.1234 foo.1235 foo.1236 etc. based on the PID in each case. When it comes to debugging a defect reported in foo.1236, we can’t clearly see how to do that since we don’t know whether this log came from running foo with red, or blue, or …

With Valgrind, the command-line is captured in the logged output in each case, so debugging alleged defects is simplified somewhat.  Is there any way to achieve a similar ‘command-line logging’ capability with Asan ?

I’ve examined the various ASAN_OPTION settings and have not found anything useful so far.

I’ve also looked at the various sanitizer interface APIs and see that I can arrange for callbacks when Asan is about to report a defect – so I could write my own code to capture the program’s argv[] content into a string … but I don’t see a way of then writing that info out to the sanitizer’s logging stream. It would be great if I could find an __asan_pritnf(…) equivalent that could write to the defect log so that I can make it clear which log is associated with which command-line args to the program.

Any idea whether the functionality I am trying to find exists somewhere within the Address Sanitizer, either via environment options, or via an API ? (In case it matters, I’m currently using Asan from GCC 7.3)

Thanks in advance for any help you can provide,

    Gordon