ElectricFence Exiting: mprotect() failed: Cannot allocate memory

This means roughly 'it is more likely that the system ran out of memory than that the application contained a programming error'. But this is again a question which can be answered very simply: Check the PC/IP value at the time of the segfault. That's either within malloc (as the OP has repeatedly claimed) or within application code.

So, what is it?

Another option is to force a segfault, ie assign to the area when the pointer is null. The values of the various CPU registers, especially the program counter, can then (in combination with a disasembler) be used to determine the location of the crash and hence, the condition at the time of the test.

I am trying to use DUMA to find the problem and am getting the following error when I try to link to the DUMA library:

# LD_PRELOAD=/lib/libduma.a /bin/snmpd & # ERROR: ld.so: object '/lib/libduma.a' from LD_PRELOAD cannot be preloaded: ignored.

What can cause this error when using LD_PRELOAD?

Only an executable object (.e_type is ET_DYN or ET_EXEC) can be pre-loaded. An archive library (*.a) that contains ET_REL files cannot be pre-loaded.

It amazes me that in all this time you never managed to answer a simple question: is the crash *in* malloc, or is it in your own code?

You are continuing to debug this as if there is malloc corruption, and this will prove futile if the crash is (as I suspect) in your own code instead.

You can only preload shared libraries.

Besides, reading man page for libduma, I see that it uses *exact* same strategy as efence: a guard page after every allocation.

So, once you manage to build a shared libduma.so, and preload it; it will most likely fail just like efence did, because the overhead of guard pages is too great for majority of real-world (non-toy) applications.

Cheers,