On Wed, 21 Oct 2009, Alexander Best wrote:
this code serves only one purpose: to trigger a segfault. i don't use the code for any other purpose. i was under the impression that mmap() should either succeed or fail (tertium non datur). mmap's manual doesn't say anything about mmap() causing segfaults.
Have you tried ktracing the application? I think you'll find that mmap(2) system call succeeded fine, and that the segfault comes from attempting to execute the address in libc on return to userspace, as a result of libc not being at that address anymore (since you removed its mapping). You can use procstat -v to inspect address space use by processes, but as a general rule you don't want to pass anything other than an address of 0x0 to mmap(2) unless you're very carefully managing the address space of the process. Many userspace libraries are involved in using that address space, but especially the runtime linker which begins execution in userspace when a binary is started.
Robert N M Watson Computer Laboratory University of Cambridge _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
