[PATCH 1/1] mm/madvise: initialize prev pointer in madvise_walk_vmas

[Lance Yang <ioworker0@gmail.com>]

From: Lance Yang <lance.yang@linux.dev>

The prev pointer was uninitialized, which could lead to undefined behavior
where its address is taken and passed to the visit() callback without being
assigned a value.

Initializing it to NULL makes the code safer and prevents potential bugs
if a future callback function attempts to read from it.

Signed-off-by: Lance Yang <lance.yang@linux.dev>
---
 mm/madvise.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 267d8e4adf31..c87325000303 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1536,10 +1536,10 @@ int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
 				   struct vm_area_struct **prev, unsigned long start,
 				   unsigned long end, void *arg))
 {
+	struct vm_area_struct *prev = NULL;
 	struct vm_area_struct *vma;
-	struct vm_area_struct *prev;
-	unsigned long tmp;
 	int unmapped_error = 0;
+	unsigned long tmp;
 	int error;
 
 	/*
-- 
2.49.0