[PATCH] mm: Check we have the right vma in access_process_vm()

[Michael Ellerman]

In access_process_vm() we need to check that we have found the right
vma, not the following vma, before we try to access it. Otherwise
we might call the vma's access routine with an address which does
not fall inside the vma.

Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx>
---
 mm/memory.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 5823698..7e6f17b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3619,7 +3619,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
 			 */
 #ifdef CONFIG_HAVE_IOREMAP_PROT
 			vma = find_vma(mm, addr);
-			if (!vma)
+			if (!vma || vma->vm_start > addr)
 				break;
 			if (vma->vm_ops && vma->vm_ops->access)
 				ret = vma->vm_ops->access(vma, addr, buf,
-- 
1.7.1

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