Mike McCormack mike_mccormack@start.com.au writes:
your patch produced a yes, BUT when i changed the offset value to 0x400, and it failed ... see new patch below.
That's a bug in glibc 2.1.3. This is from the mmap64 source:
[offset is in ecx:edx] testl $0x3ff, %edx jne L(einval) shrdl $12, %ecx, %edx /* mmap2 takes the offset in pages. */ shrl $12, %ecx
But of course 0x3ff only tests 10 bits, not 12, so if bits 10 or 11 are set they will be silently dropped. This has been fixed in glibc-2.2.
Another related problem is that even without this bug, mmap64 will always refuse to do an unaligned mmap, even if the kernel might have accepted it (with kernel 2.2.x for instance). Maybe the best solution would be to directly call the mmap syscall instead of mmap2 when mapping executables, this would fix both problems.
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Alexandre Julliard