svn commit: r218019 - head/sys/kern

Jilles Tjoelker jilles at FreeBSD.org
Fri Jan 28 15:29:36 UTC 2011


Author: jilles
Date: Fri Jan 28 15:29:35 2011
New Revision: 218019
URL: http://svn.freebsd.org/changeset/base/218019

Log:
  Do not trip a KASSERT if /dev/null cannot be opened for a setuid program.
  
  The fdcheckstd() function makes sure fds 0, 1 and 2 are open by opening
  /dev/null. If this fails (e.g. missing devfs or wrong permissions),
  fdcheckstd() will return failure and the process will exit as if it received
  SIGABRT. The KASSERT is only to check that kern_open() returns the expected
  fd, given that it succeeded.
  
  Tripping the KASSERT is most likely if fd 0 is open but fd 1 or 2 are not.
  
  MFC after:	2 weeks

Modified:
  head/sys/kern/kern_descrip.c

Modified: head/sys/kern/kern_descrip.c
==============================================================================
--- head/sys/kern/kern_descrip.c	Fri Jan 28 15:25:46 2011	(r218018)
+++ head/sys/kern/kern_descrip.c	Fri Jan 28 15:29:35 2011	(r218019)
@@ -2024,10 +2024,10 @@ fdcheckstd(struct thread *td)
 			error = kern_open(td, "/dev/null", UIO_SYSSPACE,
 			    O_RDWR, 0);
 			devnull = td->td_retval[0];
-			KASSERT(devnull == i, ("oof, we didn't get our fd"));
 			td->td_retval[0] = save;
 			if (error)
 				break;
+			KASSERT(devnull == i, ("oof, we didn't get our fd"));
 		} else {
 			error = do_dup(td, DUP_FIXED, devnull, i, &retval);
 			if (error != 0)


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