* [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
@ 2014-07-04 17:07 ` Emil Goode
0 siblings, 0 replies; 6+ messages in thread
From: Emil Goode @ 2014-07-04 17:07 UTC (permalink / raw)
To: Ralf Baechle, Paul Gortmaker, John Crispin
Cc: linux-mips, linux-kernel, kernel-janitors, Emil Goode
We check that the struct vm_area_struct pointer vma is NULL and
then dereference it. The intent must have been to check that
vma is not NULL before we dereference it in the next condition.
Signed-off-by: Emil Goode <emilgoode@gmail.com>
---
arch/mips/mm/tlb-r3k.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/mm/tlb-r3k.c b/arch/mips/mm/tlb-r3k.c
index d657493..6546758 100644
--- a/arch/mips/mm/tlb-r3k.c
+++ b/arch/mips/mm/tlb-r3k.c
@@ -158,7 +158,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
int cpu = smp_processor_id();
- if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
+ if (vma && cpu_context(cpu, vma->vm_mm) != 0) {
unsigned long flags;
int oldpid, newpid, idx;
--
1.7.10.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
@ 2014-07-04 17:07 ` Emil Goode
0 siblings, 0 replies; 6+ messages in thread
From: Emil Goode @ 2014-07-04 17:07 UTC (permalink / raw)
To: Ralf Baechle, Paul Gortmaker, John Crispin
Cc: linux-mips, linux-kernel, kernel-janitors, Emil Goode
We check that the struct vm_area_struct pointer vma is NULL and
then dereference it. The intent must have been to check that
vma is not NULL before we dereference it in the next condition.
Signed-off-by: Emil Goode <emilgoode@gmail.com>
---
arch/mips/mm/tlb-r3k.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/mm/tlb-r3k.c b/arch/mips/mm/tlb-r3k.c
index d657493..6546758 100644
--- a/arch/mips/mm/tlb-r3k.c
+++ b/arch/mips/mm/tlb-r3k.c
@@ -158,7 +158,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
int cpu = smp_processor_id();
- if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
+ if (vma && cpu_context(cpu, vma->vm_mm) != 0) {
unsigned long flags;
int oldpid, newpid, idx;
--
1.7.10.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
2014-07-04 17:07 ` Emil Goode
@ 2014-07-04 21:52 ` Jonas Gorski
-1 siblings, 0 replies; 6+ messages in thread
From: Jonas Gorski @ 2014-07-04 21:52 UTC (permalink / raw)
To: Emil Goode
Cc: Ralf Baechle, Paul Gortmaker, John Crispin, MIPS Mailing List,
linux-kernel, kernel-janitors
On Fri, Jul 4, 2014 at 7:07 PM, Emil Goode <emilgoode@gmail.com> wrote:
> We check that the struct vm_area_struct pointer vma is NULL and
> then dereference it. The intent must have been to check that
> vma is not NULL before we dereference it in the next condition.
Actually if it is NULL, then it will short-cut and won't dereference
it (because !vma is true it can never become false again), so the
condition would be fine previously.
But, looking at the code a few lines into branch:
if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
unsigned long flags;
int oldpid, newpid, idx;
#ifdef DEBUG_TLB
printk("[tlbpage<%lu,0x%08lx>]", cpu_context(cpu,
vma->vm_mm), page);
#endif
newpid = cpu_context(cpu, vma->vm_mm) & ASID_MASK;
it will be then dereferenced here, so the change is actually sensible,
even if the description isn't quite spot-on where it breaks.
Jonas
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
@ 2014-07-04 21:52 ` Jonas Gorski
0 siblings, 0 replies; 6+ messages in thread
From: Jonas Gorski @ 2014-07-04 21:52 UTC (permalink / raw)
To: Emil Goode
Cc: Ralf Baechle, Paul Gortmaker, John Crispin, MIPS Mailing List,
linux-kernel, kernel-janitors
On Fri, Jul 4, 2014 at 7:07 PM, Emil Goode <emilgoode@gmail.com> wrote:
> We check that the struct vm_area_struct pointer vma is NULL and
> then dereference it. The intent must have been to check that
> vma is not NULL before we dereference it in the next condition.
Actually if it is NULL, then it will short-cut and won't dereference
it (because !vma is true it can never become false again), so the
condition would be fine previously.
But, looking at the code a few lines into branch:
if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
unsigned long flags;
int oldpid, newpid, idx;
#ifdef DEBUG_TLB
printk("[tlbpage<%lu,0x%08lx>]", cpu_context(cpu,
vma->vm_mm), page);
#endif
newpid = cpu_context(cpu, vma->vm_mm) & ASID_MASK;
it will be then dereferenced here, so the change is actually sensible,
even if the description isn't quite spot-on where it breaks.
Jonas
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
2014-07-04 21:52 ` Jonas Gorski
@ 2014-07-05 0:30 ` Emil Goode
-1 siblings, 0 replies; 6+ messages in thread
From: Emil Goode @ 2014-07-05 0:30 UTC (permalink / raw)
To: Jonas Gorski
Cc: Ralf Baechle, Paul Gortmaker, John Crispin, MIPS Mailing List,
linux-kernel, kernel-janitors
Hello Jonas,
On Fri, Jul 04, 2014 at 11:52:51PM +0200, Jonas Gorski wrote:
> On Fri, Jul 4, 2014 at 7:07 PM, Emil Goode <emilgoode@gmail.com> wrote:
> > We check that the struct vm_area_struct pointer vma is NULL and
> > then dereference it. The intent must have been to check that
> > vma is not NULL before we dereference it in the next condition.
>
> Actually if it is NULL, then it will short-cut and won't dereference
> it (because !vma is true it can never become false again), so the
> condition would be fine previously.
>
> But, looking at the code a few lines into branch:
>
> if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
> unsigned long flags;
> int oldpid, newpid, idx;
>
> #ifdef DEBUG_TLB
> printk("[tlbpage<%lu,0x%08lx>]", cpu_context(cpu,
> vma->vm_mm), page);
> #endif
> newpid = cpu_context(cpu, vma->vm_mm) & ASID_MASK;
>
> it will be then dereferenced here, so the change is actually sensible,
> even if the description isn't quite spot-on where it breaks.
Sorry, this is what I meant but failed to explain clearly.
Perhaps the following is a bit better?
We check that the struct vm_area_struct pointer vma is NULL and then
dereference it a few lines below. The intent must have been to make sure
that vma is not NULL and then to check the value from cpu_context() for the
condition to be true.
Best regards,
Emil Goode
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page()
@ 2014-07-05 0:30 ` Emil Goode
0 siblings, 0 replies; 6+ messages in thread
From: Emil Goode @ 2014-07-05 0:30 UTC (permalink / raw)
To: Jonas Gorski
Cc: Ralf Baechle, Paul Gortmaker, John Crispin, MIPS Mailing List,
linux-kernel, kernel-janitors
Hello Jonas,
On Fri, Jul 04, 2014 at 11:52:51PM +0200, Jonas Gorski wrote:
> On Fri, Jul 4, 2014 at 7:07 PM, Emil Goode <emilgoode@gmail.com> wrote:
> > We check that the struct vm_area_struct pointer vma is NULL and
> > then dereference it. The intent must have been to check that
> > vma is not NULL before we dereference it in the next condition.
>
> Actually if it is NULL, then it will short-cut and won't dereference
> it (because !vma is true it can never become false again), so the
> condition would be fine previously.
>
> But, looking at the code a few lines into branch:
>
> if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
> unsigned long flags;
> int oldpid, newpid, idx;
>
> #ifdef DEBUG_TLB
> printk("[tlbpage<%lu,0x%08lx>]", cpu_context(cpu,
> vma->vm_mm), page);
> #endif
> newpid = cpu_context(cpu, vma->vm_mm) & ASID_MASK;
>
> it will be then dereferenced here, so the change is actually sensible,
> even if the description isn't quite spot-on where it breaks.
Sorry, this is what I meant but failed to explain clearly.
Perhaps the following is a bit better?
We check that the struct vm_area_struct pointer vma is NULL and then
dereference it a few lines below. The intent must have been to make sure
that vma is not NULL and then to check the value from cpu_context() for the
condition to be true.
Best regards,
Emil Goode
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-07-05 0:31 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-07-04 17:07 [PATCH] MIPS: Fix incorrect NULL check in local_flush_tlb_page() Emil Goode
2014-07-04 17:07 ` Emil Goode
2014-07-04 21:52 ` Jonas Gorski
2014-07-04 21:52 ` Jonas Gorski
2014-07-05 0:30 ` Emil Goode
2014-07-05 0:30 ` Emil Goode
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