On Friday, February 21, 2014 5:29:09 pm Mateusz Guzik wrote: > Author: mjg > Date: Fri Feb 21 22:29:09 2014 > New Revision: 262309 > URL: http://svnweb.freebsd.org/changeset/base/262309 > > Log: > Fix a race between kern_proc_{o,}filedesc_out and fdescfree leading > to use-after-free. > > fdescfree proceeds to free file pointers once fd_refcnt reaches 0, but > kern_proc_{o,}filedesc_out only checked for hold count.
Can you describe the race in more detail? The kern_* routines hold FILEDESC_SLOCK() while they read the file which should prevent fdescfree() from free'ing any files. Note that fdfree() (called under FILEDESC_XLOCK() clears the file pointer to NULL via the bzero(), so the sysctl handler should only see non-NULL pointers for files that are not yet free'd. -- John Baldwin _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
