Subject: [PATCH AUTOSEL 5.10 02/10] powerpc/mm: Fix null-pointer dereference in pgtable_cache_add

From: Sasha Levin <[email-masked]>
Date: Mon, 15 Jan 2024 18:27:51 -0500

From: Kunwu Chan <[email-masked]>

[ 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 <[email-masked]>
Suggested-by: Michael Ellerman <[email-masked]>
Signed-off-by: Kunwu Chan <[email-masked]>
Signed-off-by: Michael Ellerman <[email-masked]>
Link: https://msgid.link/[email-masked]
Signed-off-by: Sasha Levin <[email-masked]>
---
 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 8e0d792ac296..52a20c97e46e 100644
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -111,7 +111,7 @@ void pgtable_cache_add(unsigned int shift)
 	 * 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
@@ -124,7 +124,8 @@ void pgtable_cache_add(unsigned int shift)
 
 	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(shift));
+	if (name)
+		new = kmem_cache_create(name, table_size, align, 0, ctor(shift));
 	if (!new)
 		panic("Could not allocate pgtable cache for order %d", shift);
 
-- 
2.43.0