Shachar Shemesh wine-devel@sun.consumer.org.il writes:
Trying to run IDA with a kernel without grsecurity indeed works.
Can anyone explain why the security patches block the 00400000 address from being used?
It's because the security patches map standard libraries like libc at this address (the idea is to make pointers to libc routines contain a 0 byte to make it harder to use them in string buffer overflows).