[PATCH v2] powerpc/mm: Fix null-pointer dereference in pgtable_cache_add

[Kunwu Chan]

kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure. Ensure the allocation was successful
by checking the pointer validity.

Suggested-by: Christophe Leroy <christophe.leroy at csgroup.eu>
Suggested-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Kunwu Chan <chentao at kylinos.cn>
---
v2: Use "panic" instead of "return"
---
 arch/powerpc/mm/init-common.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
index 119ef491f797..9788950b33f5 100644
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -139,6 +139,8 @@ void pgtable_cache_add(unsigned int shift)
 
 	align = max_t(unsigned long, align, minalign);
 	name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
+	if (!name)
+		panic("Failed to allocate memory for order %d", shift);
 	new = kmem_cache_create(name, table_size, align, 0, ctor(shift));
 	if (!new)
 		panic("Could not allocate pgtable cache for order %d", shift);
-- 
2.34.1