[PATCH v2] riscv: mm: add null check for find_vm_area in __set_memory

[Osama Abdelkader]

find_vm_area() can return NULL. Add a null check to avoid potential
null pointer dereference, matching the pattern used by other arches.

Fixes: 311cd2f6e253 ("riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings")
Cc: stable at vger.kernel.org
Signed-off-by: Osama Abdelkader <osama.abdelkader at gmail.com>
---
v2:
- Add Cc: stable at vger.kernel.org
- Add Fixes: tag
- mention __set_memory in the commit message
---
 arch/riscv/mm/pageattr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 3f76db3d2769..46a999c86b26 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -289,6 +289,10 @@ static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
 		int i, page_start;
 
 		area = find_vm_area((void *)start);
+		if (!area) {
+			ret = -EINVAL;
+			goto unlock;
+		}
 		page_start = (start - (unsigned long)area->addr) >> PAGE_SHIFT;
 
 		for (i = page_start; i < page_start + numpages; ++i) {
-- 
2.43.0