Segfaults in malloc() and malloc_consolidate()

Question

My application segfaults sometimes and mainly in malloc() and malloc_consolidate() when I look at the backtrace in gdb.

I verified that the machine has enough memory available, it didn't even start swapping. I checked ulimits for data segement and max memory size and both are set to 'unlimited'. I also ran the application under valgrind and didn't find any memory errors.

Now I'm out of ideas what else might be causing these segfaults. Any Ideas ?

Update: Since I'm not finding anything with valgrind (or ptrcheck), could it be that another application is trashing libc's memory structure or is there a separate structure for each process ?

Answer 1

From http://www.gnu.org/s/libc/manual/html_node/Heap-Consistency-Checking.html#Heap-Consistency-Checking:

Another possibility to check for and guard against bugs in the use of malloc, realloc and free is to set the environment variable MALLOC_CHECK_. When MALLOC_CHECK_ is set, a special (less efficient) implementation is used which is designed to be tolerant against simple errors, such as double calls of free with the same argument, or overruns of a single byte (off-by-one bugs). Not all such errors can be protected against, however, and memory leaks can result. If MALLOC_CHECK_ is set to 0, any detected heap corruption is silently ignored; if set to 1, a diagnostic is printed on stderr; if set to 2, abort is called immediately. This can be useful because otherwise a crash may happen much later, and the true cause for the problem is then very hard to track down.