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* [PATCH] x86/platform/uv: move kmalloc() NULL check routine
@ 2019-09-05 23:29 ` Austin Kim
  0 siblings, 0 replies; 5+ messages in thread
From: Austin Kim @ 2019-09-05 23:29 UTC (permalink / raw)
  To: tglx, mingo, bp, x86
  Cc: dvhart, andy, hpa, x86, gregkh, allison, armijn, kjlu,
	platform-driver-x86, linux-kernel

The result of kmalloc should have been checked ahead of below statement:
	pqp = (struct bau_pq_entry *)vp;

Move BUG_ON(!vp) before above statement.

Signed-off-by: Austin Kim <austindh.kim@gmail.com>
---
 arch/x86/platform/uv/tlb_uv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 20c389a..5f0a96bf 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1804,9 +1804,9 @@ static void pq_init(int node, int pnode)
 
 	plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
 	vp = kmalloc_node(plsize, GFP_KERNEL, node);
-	pqp = (struct bau_pq_entry *)vp;
-	BUG_ON(!pqp);
+	BUG_ON(!vp);
 
+	pqp = (struct bau_pq_entry *)vp;
 	cp = (char *)pqp + 31;
 	pqp = (struct bau_pq_entry *)(((unsigned long)cp >> 5) << 5);
 
-- 
2.6.2


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH] x86/platform/uv: move kmalloc() NULL check routine
@ 2019-09-05 23:29 ` Austin Kim
  0 siblings, 0 replies; 5+ messages in thread
From: Austin Kim @ 2019-09-05 23:29 UTC (permalink / raw)
  To: tglx, mingo, bp
  Cc: dvhart, andy, hpa, x86, gregkh, allison, armijn, kjlu,
	platform-driver-x86, linux-kernel

The result of kmalloc should have been checked ahead of below statement:
	pqp = (struct bau_pq_entry *)vp;

Move BUG_ON(!vp) before above statement.

Signed-off-by: Austin Kim <austindh.kim@gmail.com>
---
 arch/x86/platform/uv/tlb_uv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 20c389a..5f0a96bf 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1804,9 +1804,9 @@ static void pq_init(int node, int pnode)
 
 	plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
 	vp = kmalloc_node(plsize, GFP_KERNEL, node);
-	pqp = (struct bau_pq_entry *)vp;
-	BUG_ON(!pqp);
+	BUG_ON(!vp);
 
+	pqp = (struct bau_pq_entry *)vp;
 	cp = (char *)pqp + 31;
 	pqp = (struct bau_pq_entry *)(((unsigned long)cp >> 5) << 5);
 
-- 
2.6.2

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] x86/platform/uv: move kmalloc() NULL check routine
  2019-09-05 23:29 ` Austin Kim
  (?)
@ 2019-09-06  9:32 ` Greg KH
  2019-09-06 10:43   ` Peter Zijlstra
  -1 siblings, 1 reply; 5+ messages in thread
From: Greg KH @ 2019-09-06  9:32 UTC (permalink / raw)
  To: Austin Kim
  Cc: tglx, mingo, bp, x86, dvhart, andy, hpa, allison, armijn, kjlu,
	platform-driver-x86, linux-kernel

On Fri, Sep 06, 2019 at 08:29:51AM +0900, Austin Kim wrote:
> The result of kmalloc should have been checked ahead of below statement:
> 	pqp = (struct bau_pq_entry *)vp;
> 
> Move BUG_ON(!vp) before above statement.
> 
> Signed-off-by: Austin Kim <austindh.kim@gmail.com>
> ---
>  arch/x86/platform/uv/tlb_uv.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
> index 20c389a..5f0a96bf 100644
> --- a/arch/x86/platform/uv/tlb_uv.c
> +++ b/arch/x86/platform/uv/tlb_uv.c
> @@ -1804,9 +1804,9 @@ static void pq_init(int node, int pnode)
>  
>  	plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
>  	vp = kmalloc_node(plsize, GFP_KERNEL, node);
> -	pqp = (struct bau_pq_entry *)vp;
> -	BUG_ON(!pqp);
> +	BUG_ON(!vp);

Ick!  Don't crash the whole machine if you are out of memory, that's a
totally lazy and broken driver.  Fix this up properly please.

But the original code is just fine (from a this is doing what I want it
to do point of view), I don't see the need to change anything here, you
did not modify any logic at all.

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] x86/platform/uv: move kmalloc() NULL check routine
  2019-09-06  9:32 ` Greg KH
@ 2019-09-06 10:43   ` Peter Zijlstra
  2019-09-06 10:53     ` Greg KH
  0 siblings, 1 reply; 5+ messages in thread
From: Peter Zijlstra @ 2019-09-06 10:43 UTC (permalink / raw)
  To: Greg KH
  Cc: Austin Kim, tglx, mingo, bp, x86, dvhart, andy, hpa, allison,
	armijn, kjlu, platform-driver-x86, linux-kernel

On Fri, Sep 06, 2019 at 11:32:52AM +0200, Greg KH wrote:
> On Fri, Sep 06, 2019 at 08:29:51AM +0900, Austin Kim wrote:
> > The result of kmalloc should have been checked ahead of below statement:
> > 	pqp = (struct bau_pq_entry *)vp;
> > 
> > Move BUG_ON(!vp) before above statement.
> > 
> > Signed-off-by: Austin Kim <austindh.kim@gmail.com>
> > ---
> >  arch/x86/platform/uv/tlb_uv.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
> > index 20c389a..5f0a96bf 100644
> > --- a/arch/x86/platform/uv/tlb_uv.c
> > +++ b/arch/x86/platform/uv/tlb_uv.c
> > @@ -1804,9 +1804,9 @@ static void pq_init(int node, int pnode)
> >  
> >  	plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
> >  	vp = kmalloc_node(plsize, GFP_KERNEL, node);
> > -	pqp = (struct bau_pq_entry *)vp;
> > -	BUG_ON(!pqp);
> > +	BUG_ON(!vp);
> 
> Ick!  Don't crash the whole machine if you are out of memory, that's a
> totally lazy and broken driver.  Fix this up properly please.

This is boot time init; if memory allocation fails, we're in trouble, no
way forward no way back.

It is not uncommon to have BUG_ON() for alloc failing during boot.

> But the original code is just fine (from a this is doing what I want it
> to do point of view), I don't see the need to change anything here, you
> did not modify any logic at all.

Agreed, the patch seems entirely pointless.

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH] x86/platform/uv: move kmalloc() NULL check routine
  2019-09-06 10:43   ` Peter Zijlstra
@ 2019-09-06 10:53     ` Greg KH
  0 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2019-09-06 10:53 UTC (permalink / raw)
  To: Peter Zijlstra
  Cc: Austin Kim, tglx, mingo, bp, x86, dvhart, andy, hpa, allison,
	armijn, kjlu, platform-driver-x86, linux-kernel

On Fri, Sep 06, 2019 at 12:43:41PM +0200, Peter Zijlstra wrote:
> On Fri, Sep 06, 2019 at 11:32:52AM +0200, Greg KH wrote:
> > On Fri, Sep 06, 2019 at 08:29:51AM +0900, Austin Kim wrote:
> > > The result of kmalloc should have been checked ahead of below statement:
> > > 	pqp = (struct bau_pq_entry *)vp;
> > > 
> > > Move BUG_ON(!vp) before above statement.
> > > 
> > > Signed-off-by: Austin Kim <austindh.kim@gmail.com>
> > > ---
> > >  arch/x86/platform/uv/tlb_uv.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
> > > index 20c389a..5f0a96bf 100644
> > > --- a/arch/x86/platform/uv/tlb_uv.c
> > > +++ b/arch/x86/platform/uv/tlb_uv.c
> > > @@ -1804,9 +1804,9 @@ static void pq_init(int node, int pnode)
> > >  
> > >  	plsize = (DEST_Q_SIZE + 1) * sizeof(struct bau_pq_entry);
> > >  	vp = kmalloc_node(plsize, GFP_KERNEL, node);
> > > -	pqp = (struct bau_pq_entry *)vp;
> > > -	BUG_ON(!pqp);
> > > +	BUG_ON(!vp);
> > 
> > Ick!  Don't crash the whole machine if you are out of memory, that's a
> > totally lazy and broken driver.  Fix this up properly please.
> 
> This is boot time init; if memory allocation fails, we're in trouble, no
> way forward no way back.
> 
> It is not uncommon to have BUG_ON() for alloc failing during boot.

Hey, how come you get to get away with this here, and in the tty layer I
had to do all sorts of foolish things just for the same "impossible"
thing because syzbot found a way to emulate such lunacy?

Just you wait until the fuzzers get ahold of this code...  :)

greg k-h

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2019-09-06 10:53 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-05 23:29 [PATCH] x86/platform/uv: move kmalloc() NULL check routine Austin Kim
2019-09-05 23:29 ` Austin Kim
2019-09-06  9:32 ` Greg KH
2019-09-06 10:43   ` Peter Zijlstra
2019-09-06 10:53     ` Greg KH

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