[Bug nscd/9750] New: nscd gc() segmentation fault by estimation failure of alloca()'s stack usage

["j-nomura at ce dot jp dot nec dot com" <sourceware-bugzilla at sourceware dot org>]

The garbage collection function, gc(), estimates the stack usage
to switch the allocation method.

For the allocation of 'struct moveinfo', it adds the size given to alloca().
http://sourceware.org/cgi-bin/cvsweb.cgi/libc/nscd/mem.c.diff?r1=1.3.2.8&r2=1.3.2.9&cvsroot=glibc
In fucntion gc():
          new_move = alloca (sizeof (*new_move));
          stack_used += sizeof (*new_move);

However, alloca() seems to allocate additional +16 bytes for each allocation
in my case (Fedora 9, x86_64).
As a result, the estimation gets wrong and gc() ends up to segmentation fault.

Simply summing up the extra 16 bytes to the estimation would solve the problem.

Or if there is a better method to determine the current stack usage,
it might be better to switch the whole estimation stuff to use that.

-- 
           Summary: nscd gc() segmentation fault by estimation failure of
                    alloca()'s stack usage
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: nscd
        AssignedTo: drepper at redhat dot com
        ReportedBy: j-nomura at ce dot jp dot nec dot com
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=9750

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