From: Petr Mladek
> Sent: 15 May 2019 08:36
> On Tue 2019-05-14 14:37:51, Steven Rostedt wrote:
> >
> > [ Purple is a nice shade on the bike shed. ;-) ]
> >
> > On Tue, 14 May 2019 11:02:17 +0200
> > Geert Uytterhoeven wrote:
> >
> > > On Tue, May 14, 2019 at 10:29 AM David Laight
> > > wrote:
On Wed 2019-05-15 09:23:05, Geert Uytterhoeven wrote:
> Hi Steve,
>
> On Tue, May 14, 2019 at 9:35 PM Steven Rostedt wrote:
> > On Tue, 14 May 2019 21:13:06 +0200
> > Geert Uytterhoeven wrote:
> > > > > Do we care about the value? "(-E%u)"?
> > > >
> > > > That too could be confusing. What
On Tue 2019-05-14 14:37:51, Steven Rostedt wrote:
>
> [ Purple is a nice shade on the bike shed. ;-) ]
>
> On Tue, 14 May 2019 11:02:17 +0200
> Geert Uytterhoeven wrote:
>
> > On Tue, May 14, 2019 at 10:29 AM David Laight
> > wrote:
> > > > And I like Steven's "(fault)" idea.
> > > > How
Hi Steve,
On Tue, May 14, 2019 at 9:35 PM Steven Rostedt wrote:
> On Tue, 14 May 2019 21:13:06 +0200
> Geert Uytterhoeven wrote:
> > > > Do we care about the value? "(-E%u)"?
> > >
> > > That too could be confusing. What would (-E22) be considered by a user
> > > doing an sprintf() on some
On (05/14/19 21:13), Geert Uytterhoeven wrote:
> I would immediately understand there's a missing IS_ERR() check in a
> function that can return -EINVAL, without having to add a new printk()
> to find out what kind of bogus value has been received, and without
> having to reboot, and trying to
On Tue, 14 May 2019 21:13:06 +0200
Geert Uytterhoeven wrote:
> > > Do we care about the value? "(-E%u)"?
> >
> > That too could be confusing. What would (-E22) be considered by a user
> > doing an sprintf() on some string. I know that would confuse me, or I
> > would think that it was what the
Hi Steve,
On Tue, May 14, 2019 at 8:37 PM Steven Rostedt wrote:
> On Tue, 14 May 2019 11:02:17 +0200
> Geert Uytterhoeven wrote:
> > On Tue, May 14, 2019 at 10:29 AM David Laight
> > wrote:
> > > > And I like Steven's "(fault)" idea.
> > > > How about this:
> > > >
> > > > if ptr <
[ Purple is a nice shade on the bike shed. ;-) ]
On Tue, 14 May 2019 11:02:17 +0200
Geert Uytterhoeven wrote:
> On Tue, May 14, 2019 at 10:29 AM David Laight wrote:
> > > And I like Steven's "(fault)" idea.
> > > How about this:
> > >
> > > if ptr < PAGE_SIZE -> "(null)"
>
On Tue, May 14, 2019 at 10:29 AM David Laight wrote:
> > And I like Steven's "(fault)" idea.
> > How about this:
> >
> > if ptr < PAGE_SIZE -> "(null)"
> > if IS_ERR_VALUE(ptr)-> "(fault)"
> >
> > -ss
>
> Or:
> if (ptr < PAGE_SIZE)
>
> And I like Steven's "(fault)" idea.
> How about this:
>
> if ptr < PAGE_SIZE -> "(null)"
> if IS_ERR_VALUE(ptr)-> "(fault)"
>
> -ss
Or:
if (ptr < PAGE_SIZE)
return ptr ? "(null+)" : "(null)";
if IS_ERR_VALUE(ptr)
On (05/14/19 11:07), Sergey Senozhatsky wrote:
> How about this:
>
> if ptr < PAGE_SIZE -> "(null)"
No, this is totally stupid. Forget about it. Sorry.
> if IS_ERR_VALUE(ptr)-> "(fault)"
But Steven's "(fault)" is nice.
-ss
On (05/13/19 14:42), Petr Mladek wrote:
> > The "(null)" is good enough by itself and already an established
> > practice..
>
> (efault) made more sense with the probe_kernel_read() that
> checked wide range of addresses. Well, I still think that
> it makes sense to distinguish a pure NULL. And
On Mon, 13 May 2019 14:42:20 +0200
Petr Mladek wrote:
> > The "(null)" is good enough by itself and already an established
> > practice..
>
> (efault) made more sense with the probe_kernel_read() that
> checked wide range of addresses. Well, I still think that
> it makes sense to distinguish
On Mon 2019-05-13 12:13:20, Andy Shevchenko wrote:
> On Mon, May 13, 2019 at 08:52:41AM +, David Laight wrote:
> > From: christophe leroy
> > > Sent: 10 May 2019 18:35
> > > Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
> > > > On Fri, 10 May 2019 10:42:13 +0200
> > > > Petr Mladek wrote:
>
On Fri 2019-05-10 12:40:58, Steven Rostedt wrote:
> On Fri, 10 May 2019 18:32:58 +0200
> Martin Schwidefsky wrote:
>
> > On Fri, 10 May 2019 12:24:01 -0400
> > Steven Rostedt wrote:
> >
> > > On Fri, 10 May 2019 10:42:13 +0200
> > > Petr Mladek wrote:
> > >
> > > > static const char
On Mon, May 13, 2019 at 08:52:41AM +, David Laight wrote:
> From: christophe leroy
> > Sent: 10 May 2019 18:35
> > Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
> > > On Fri, 10 May 2019 10:42:13 +0200
> > > Petr Mladek wrote:
> > >> -if (probe_kernel_address(ptr, byte))
> > >> +
From: christophe leroy
> Sent: 10 May 2019 18:35
> Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
> > On Fri, 10 May 2019 10:42:13 +0200
> > Petr Mladek wrote:
> >
> >> static const char *check_pointer_msg(const void *ptr)
> >> {
> >> - char byte;
> >> -
> >>if (!ptr)
> >>
Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
On Fri, 10 May 2019 10:42:13 +0200
Petr Mladek wrote:
static const char *check_pointer_msg(const void *ptr)
{
- char byte;
-
if (!ptr)
return "(null)";
- if (probe_kernel_address(ptr, byte))
+ if
On Fri, 10 May 2019 12:40:58 -0400
Steven Rostedt wrote:
> On Fri, 10 May 2019 18:32:58 +0200
> Martin Schwidefsky wrote:
>
> > On Fri, 10 May 2019 12:24:01 -0400
> > Steven Rostedt wrote:
> >
> > > On Fri, 10 May 2019 10:42:13 +0200
> > > Petr Mladek wrote:
> > >
> > > > static
On Fri, May 10, 2019 at 12:24:01PM -0400, Steven Rostedt wrote:
> On Fri, 10 May 2019 10:42:13 +0200
> Petr Mladek wrote:
>
> > static const char *check_pointer_msg(const void *ptr)
> > {
> > - char byte;
> > -
> > if (!ptr)
> > return "(null)";
> >
> > - if
On Fri, 10 May 2019 18:32:58 +0200
Martin Schwidefsky wrote:
> On Fri, 10 May 2019 12:24:01 -0400
> Steven Rostedt wrote:
>
> > On Fri, 10 May 2019 10:42:13 +0200
> > Petr Mladek wrote:
> >
> > > static const char *check_pointer_msg(const void *ptr)
> > > {
> > > - char byte;
> > > -
> >
On Fri, 10 May 2019 12:24:01 -0400
Steven Rostedt wrote:
> On Fri, 10 May 2019 10:42:13 +0200
> Petr Mladek wrote:
>
> > static const char *check_pointer_msg(const void *ptr)
> > {
> > - char byte;
> > -
> > if (!ptr)
> > return "(null)";
> >
> > - if
On Fri, 10 May 2019 10:42:13 +0200
Petr Mladek wrote:
> static const char *check_pointer_msg(const void *ptr)
> {
> - char byte;
> -
> if (!ptr)
> return "(null)";
>
> - if (probe_kernel_address(ptr, byte))
> + if ((unsigned long)ptr < PAGE_SIZE ||
On Fri 2019-05-10 10:42:13, Petr Mladek wrote:
> The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
> invalid pointers") broke boot on several architectures. The common
> pattern is that probe_kernel_read() is not working during early
> boot because userspace access
David Laight writes:
> From: Michal Suchánek
>> Sent: 09 May 2019 14:38
> ...
>> > The problem is the combination of some new code called via printk(),
>> > check_pointer() which calls probe_kernel_read(). That then calls
>> > allow_user_access() (PPC_KUAP) and that uses mmu_has_feature() too
On (05/10/19 10:42), Petr Mladek wrote:
[..]
> Fixes: 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing invalid
> pointers")
> Signed-off-by: Petr Mladek
FWIW
Reviewed-by: Sergey Senozhatsky
-ss
The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
invalid pointers") broke boot on several architectures. The common
pattern is that probe_kernel_read() is not working during early
boot because userspace access framework is not ready.
It is a generic problem. We have to
On (05/10/19 10:06), Petr Mladek wrote:
[..]
> I am going to send a patch replacing probe_kernel_address() with
> a simple check:
>
> if ((unsigned long)ptr < PAGE_SIZE || IS_ERR_VALUE(ptr))
> return "(efault)";
I'm OK with this.
Probing ptrs was a good idea, it just didn't
On Fri 2019-05-10 14:07:09, Sergey Senozhatsky wrote:
> On (05/09/19 21:47), Linus Torvalds wrote:
> >[ Sorry about html and mobile crud, I'm not at the computer right now ]
> >How about we just undo the whole misguided probe_kernel_address() thing?
>
> But the problem will remain -
Sergey Senozhatsky writes:
> On (05/09/19 21:47), Linus Torvalds wrote:
>>[ Sorry about html and mobile crud, I'm not at the computer right now ]
>>How about we just undo the whole misguided probe_kernel_address() thing?
>
> But the problem will remain - %pS/%pF on PPC (and some other
[ Sorry about html and mobile crud, I'm not at the computer right now ]
How about we just undo the whole misguided probe_kernel_address() thing?
The excuse for is was that it would avoid crashes.
It turns out that was wrong, and that it just made things much worse.
Honestly, we haven't really
On (05/09/19 21:47), Linus Torvalds wrote:
>[ Sorry about html and mobile crud, I'm not at the computer right now ]
>How about we just undo the whole misguided probe_kernel_address() thing?
But the problem will remain - %pS/%pF on PPC (and some other arch-s)
do
On (05/09/19 14:19), Petr Mladek wrote:
> 1. Report on Power:
>
> Kernel crashes very early during boot with with CONFIG_PPC_KUAP and
> CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
>
> The problem is the combination of some new code called via printk(),
> check_pointer() which calls
From: Michal Suchánek
> Sent: 09 May 2019 14:38
...
> > The problem is the combination of some new code called via printk(),
> > check_pointer() which calls probe_kernel_read(). That then calls
> > allow_user_access() (PPC_KUAP) and that uses mmu_has_feature() too early
> > (before we've patched
On Thu 2019-05-09 09:13:57, Steven Rostedt wrote:
> On Thu, 9 May 2019 14:19:23 +0200
> Petr Mladek wrote:
>
> > The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
> > invalid pointers") broke boot on several architectures. The common
> > pattern is that
On Thu, 9 May 2019 14:19:23 +0200
Petr Mladek wrote:
> The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
> invalid pointers") broke boot on several architectures. The common
> pattern is that probe_kernel_read() is not working during early
> boot because userspace access
On Thu, 9 May 2019 14:19:23 +0200
Petr Mladek wrote:
> The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
> invalid pointers") broke boot on several architectures. The common
> pattern is that probe_kernel_read() is not working during early
> boot because userspace access
On Thu, May 09, 2019 at 02:19:23PM +0200, Petr Mladek wrote:
> The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
> invalid pointers") broke boot on several architectures. The common
> pattern is that probe_kernel_read() is not working during early
> boot because userspace
The commit 3e5903eb9cff70730 ("vsprintf: Prevent crash when dereferencing
invalid pointers") broke boot on several architectures. The common
pattern is that probe_kernel_read() is not working during early
boot because userspace access framework is not ready.
The check is only the best effort.
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