Hi Andrew, while debugging I noticed the following comment in fs/binfmt_elf.c: /* * The early SET_PERSONALITY here is so that the lookup * for the interpreter happens in the namespace of the * to-be-execed image. SET_PERSONALITY can select an * alternate root. * * However, SET_PERSONALITY is NOT allowed to switch * this task into the new images's memory mapping * policy - that is, TASK_SIZE must still evaluate to * that which is appropriate to the execing application. * This is because exit_mmap() needs to have TASK_SIZE * evaluate to the size of the old image. * * So if (say) a 64-bit application is execing a 32-bit * application it is the architecture's responsibility * to defer changing the value of TASK_SIZE until the * switch really is going to happen - do this in * flush_thread(). - akpm */ At least s390 isn't doing the deferred TASK_SIZE switch. Also it seems like MIPS, PARISC and IA64 don't do it either. However from a quick a view I couldn't see that exit_mmap depends on TASK_SIZE. So is this still necessary? And the bug I was looking for is this one: in SET_PERSONALITY we do this: if (current->personality != PER_LINUX32) set_personality(PER_LINUX); However we should use the PER_MASK if we want to check for PER_LINUX32, since there are more bits in the personality flags. In case any of the 'extra' bits is set we may incorrectly set personality to PER_LINUX even when we want PER_LINUX32. Looks like more architectures should do something like: if (personality(current->personality) != PER_LINUX32) ... -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
