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Subject[PATCH] powerpc/mm: add sanity check to avoid null pointer dereference
Date
Similar to commit<0dc294f717d4>("powerpc/mm: bail out early when flushing TLB page"),
there should be a check for 'mm' to prevent Null pointer dereference
in case of 'mm' argument was legitimately passed.

Signed-off-by: Defang Bo <bodefang@126.com>
---
arch/powerpc/mm/nohash/tlb.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/nohash/tlb.c b/arch/powerpc/mm/nohash/tlb.c
index 5872f69..1d89335 100644
--- a/arch/powerpc/mm/nohash/tlb.c
+++ b/arch/powerpc/mm/nohash/tlb.c
@@ -192,6 +192,9 @@ void local_flush_tlb_mm(struct mm_struct *mm)
{
unsigned int pid;

+ if (WARN_ON(!mm))
+ return;
+
preempt_disable();
pid = mm->context.id;
if (pid != MMU_NO_CONTEXT)
@@ -205,8 +208,11 @@ void __local_flush_tlb_page(struct mm_struct *mm, unsigned long vmaddr,
{
unsigned int pid;

+ if (WARN_ON(!mm))
+ return;
+
preempt_disable();
- pid = mm ? mm->context.id : 0;
+ pid = mm->context.id;
if (pid != MMU_NO_CONTEXT)
_tlbil_va(vmaddr, pid, tsize, ind);
preempt_enable();
@@ -268,6 +274,9 @@ void flush_tlb_mm(struct mm_struct *mm)
{
unsigned int pid;

+ if (WARN_ON(!mm))
+ return;
+
preempt_disable();
pid = mm->context.id;
if (unlikely(pid == MMU_NO_CONTEXT))
--
2.7.4
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