itimer: Schedule silent NULL pointer fixup in setitimer() for removal (aa2bf9bc) · Commits · 戴 / test

setitimer() should return -EFAULT if called with an invalid pointer for value. The current code excludes a NULL pointer from this rule and silently uses it to stop the timer. This violates the spec. Warn about user space apps which rely on that feature and schedule it for removal. [ tglx: Massaged changelog, warn message and Doc entry ] Signed-off-by:

Sasikantha babu <sasikanth.v19@gmail.com> Link: http://lkml.kernel.org/r/1332340854-26053-1-git-send-email-sasikanth.v19@gmail.com Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

Documentation/feature-removal-schedule.txt

+8 −0

Original line number	Diff line number	Diff line
		@@ -529,3 +529,11 @@ When: 3.5
		Why: The old kmap_atomic() with two arguments is deprecated, we only
		keep it for backward compatibility for few cycles and then drop it.
		Who: Cong Wang <amwang@redhat.com>

		----------------------------

		What: setitimer accepts user NULL pointer (value)
		When: 3.6
		Why: setitimer is not returning -EFAULT if user pointer is NULL. This
		violates the spec.
		Who: Sasikantha Babu <sasikanth.v19@gmail.com>

kernel/itimer.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -284,8 +284,11 @@ SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
		if (value) {
		if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
		return -EFAULT;
		} else
		} else {
		memset((char *) &set_buffer, 0, sizeof(set_buffer));
		WARN_ONCE(1, "setitimer: new_value pointer is NULL."
		" Misfeature support will be removed\n");
		}

		error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
		if (error \|\| !ovalue)

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