* [PATCH] automount: check for recursive automount
@ 2014-07-03 6:21 Sascha Hauer
0 siblings, 0 replies; 6+ messages in thread
From: Sascha Hauer @ 2014-07-03 6:21 UTC (permalink / raw)
To: barebox
automount_mount calls run_command which may trigger an automount
again. This results in an endless loop. A simple way to trigger
this is:
mkdir /x; automount /x false; cd /x; something
Use a static variable to detect if we are currently in automount_mount()
and bail out if we are.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
fs/fs.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/fs.c b/fs/fs.c
index b0ac918..dd410b7 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -409,6 +409,12 @@ static void automount_mount(const char *path, int instat)
{
struct automount *am;
int ret;
+ static int in_automount;
+
+ if (in_automount)
+ return;
+
+ in_automount++;
list_for_each_entry(am, &automount_list, list) {
int len_path = strlen(path);
@@ -444,8 +450,10 @@ static void automount_mount(const char *path, int instat)
else
automount_remove(am->path);
- return;
+ break;
}
+
+ in_automount--;
}
BAREBOX_MAGICVAR(automount_path, "mountpath passed to automount scripts");
--
2.0.0
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] automount: check for recursive automount
@ 2014-07-03 8:34 Rolf Evers-Fischer
2014-07-03 8:51 ` Uwe Kleine-König
2014-07-03 9:00 ` Alessandro Rubini
0 siblings, 2 replies; 6+ messages in thread
From: Rolf Evers-Fischer @ 2014-07-03 8:34 UTC (permalink / raw)
To: s.hauer; +Cc: barebox
Hi Sascha,
Sascha Hauer <s.hauer@...> wrote:
> + static int in_automount;
> +
> + if (in_automount)
> + return;
It seems that we are using the 'in_automount' without initialization.
Shouldn't we initialize the static 'in_automount' with 0? Or can we rely
on the compiler, that all statics will be initialized with zeros?
Best regards,
Rolf
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] automount: check for recursive automount
2014-07-03 8:34 Rolf Evers-Fischer
@ 2014-07-03 8:51 ` Uwe Kleine-König
2014-07-03 9:00 ` Alessandro Rubini
1 sibling, 0 replies; 6+ messages in thread
From: Uwe Kleine-König @ 2014-07-03 8:51 UTC (permalink / raw)
To: Rolf Evers-Fischer; +Cc: barebox
On Thu, Jul 03, 2014 at 10:34:37AM +0200, Rolf Evers-Fischer wrote:
> Hi Sascha,
>
> Sascha Hauer <s.hauer@...> wrote:
> > + static int in_automount;
> > +
> > + if (in_automount)
> > + return;
>
> It seems that we are using the 'in_automount' without initialization.
> Shouldn't we initialize the static 'in_automount' with 0? Or can we rely
> on the compiler, that all statics will be initialized with zeros?
static variables are initialized to 0 (for pointers: NULL) by the
compiler.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] automount: check for recursive automount
2014-07-03 8:34 Rolf Evers-Fischer
2014-07-03 8:51 ` Uwe Kleine-König
@ 2014-07-03 9:00 ` Alessandro Rubini
2014-07-03 9:33 ` Uwe Kleine-König
1 sibling, 1 reply; 6+ messages in thread
From: Alessandro Rubini @ 2014-07-03 9:00 UTC (permalink / raw)
To: u.kleine-koenig; +Cc: barebox, embedded24
> static variables are initialized to 0 (for pointers: NULL) by the
> compiler.
Well, not really. The compiler just places them in the .bss area. It
is barebox, it is run-time initialization, that zeroes bss.
So it is barebox, not the compiler.
Uwe, I know you know this, but I'd better make it clear for
everybody. I've already seen a "specialist" writing an IPL where he
explicitly sets static variables to 0 one by one in different places
because he didn't clear bss in his assembly.
/alessandro
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] automount: check for recursive automount
2014-07-03 9:00 ` Alessandro Rubini
@ 2014-07-03 9:33 ` Uwe Kleine-König
2014-07-03 11:05 ` Rolf Evers-Fischer
0 siblings, 1 reply; 6+ messages in thread
From: Uwe Kleine-König @ 2014-07-03 9:33 UTC (permalink / raw)
To: Alessandro Rubini; +Cc: barebox, embedded24
On Thu, Jul 03, 2014 at 11:00:45AM +0200, Alessandro Rubini wrote:
> > static variables are initialized to 0 (for pointers: NULL) by the
> > compiler.
>
> Well, not really. The compiler just places them in the .bss area. It
> is barebox, it is run-time initialization, that zeroes bss.
>
> So it is barebox, not the compiler.
Yeah, in general it's even worse because there might be platforms where
NULL isn't represented by a literal 0. (Not sure if something like this
exists, but it's allowed by the standard.)
C99 tells us:
If an object that has automatic storage duration is not initialized explicitly,
its value is indeterminate. If an object that has static storage duration is
not initialized explicitly, then:
- if it has pointer type, it is initialized to a null pointer;
- if it has arithmetic type, it is initialized to (positive or unsigned) zero;
- if it is an aggregate, every member is initialized (recursively) according to
these rules;
- if it is a union, the first named member is initialized (recursively)
according to these rules.
I assume it's included in earlier standards, too, but I don't have these
handy.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2014-07-03 6:21 [PATCH] automount: check for recursive automount Sascha Hauer
2014-07-03 8:34 Rolf Evers-Fischer
2014-07-03 8:51 ` Uwe Kleine-König
2014-07-03 9:00 ` Alessandro Rubini
2014-07-03 9:33 ` Uwe Kleine-König
2014-07-03 11:05 ` Rolf Evers-Fischer
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