[PATCH AUTOSEL 4.19 1/4] powerpc/mm: Fix null-pointer dereference in pgtable_cache_add

[Sasha Levin]

From: Kunwu Chan <chentao at kylinos.cn>

[ Upstream commit f46c8a75263f97bda13c739ba1c90aced0d3b071 ]

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>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
Link: https://msgid.link/20231204023223.2447523-1-chentao@kylinos.cn
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 arch/powerpc/mm/init-common.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
index 2b656e67f2ea..927703af49be 100644
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -65,7 +65,7 @@ void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
 	 * as to leave enough 0 bits in the address to contain it. */
 	unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
 				     HUGEPD_SHIFT_MASK + 1);
-	struct kmem_cache *new;
+	struct kmem_cache *new = NULL;
 
 	/* It would be nice if this was a BUILD_BUG_ON(), but at the
 	 * moment, gcc doesn't seem to recognize is_power_of_2 as a
@@ -78,7 +78,8 @@ void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
 
 	align = max_t(unsigned long, align, minalign);
 	name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
-	new = kmem_cache_create(name, table_size, align, 0, ctor);
+	if (name)
+		new = kmem_cache_create(name, table_size, align, 0, ctor);
 	if (!new)
 		panic("Could not allocate pgtable cache for order %d", shift);
 
-- 
2.43.0