[PATCH] error out on execve with no binfmts

[PATCH] error out on execve with no binfmts

[Chris Wright]

Early calls to userspace can invoke an execve() before any binfmt handlers
are registered.  Properly return an error in this case rather than 0.
On at least one arch (x86_64) without this patch, the system will double
fault on early attempts to call_usermodehelper.  Suggestions on a better
error?

Signed-off-by: Chris Wright <chrisw@osdl.org>

===== fs/exec.c 1.142 vs edited =====
--- 1.142/fs/exec.c	2004-10-22 21:23:42 -07:00
+++ edited/fs/exec.c	2004-10-27 18:11:54 -07:00
@@ -984,7 +984,7 @@
  */
 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 {
-	int try,retval=0;
+	int try,retval;
 	struct linux_binfmt *fmt;
 #ifdef __alpha__
 	/* handle /sbin/loader.. */
@@ -1028,6 +1028,7 @@
 	/* kernel module loader fixup */
 	/* so we don't try to load run modprobe in kernel space. */
 	set_fs(USER_DS);
+	retval = -ENOENT;
 	for (try=0; try<2; try++) {
 		read_lock(&binfmt_lock);
 		for (fmt = formats ; fmt ; fmt = fmt->next) {

Re: [PATCH] error out on execve with no binfmts

[Andrew Morton]

Chris Wright <chrisw@osdl.org> wrote:
>
> Early calls to userspace can invoke an execve() before any binfmt handlers
> are registered.  Properly return an error in this case rather than 0.
> On at least one arch (x86_64) without this patch, the system will double
> fault on early attempts to call_usermodehelper.  Suggestions on a better
> error?

These handlers are installed at core_initcall() time.  Who is calling out
to userspace so early?

Re: [PATCH] error out on execve with no binfmts

[Chris Wright]

* Andrew Morton (akpm@osdl.org) wrote:
> Chris Wright <chrisw@osdl.org> wrote:
> >
> > Early calls to userspace can invoke an execve() before any binfmt handlers
> > are registered.  Properly return an error in this case rather than 0.
> > On at least one arch (x86_64) without this patch, the system will double
> > fault on early attempts to call_usermodehelper.  Suggestions on a better
> > error?
> 
> These handlers are installed at core_initcall() time.  Who is calling out
> to userspace so early?

kobject_add()->kobject_hotplug() stuff during driver_init(), like platform bus
initialization, etc.

thanks,
-chris
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