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

From: Sasha Levin
Date: Mon Jan 15 2024 - 18:40:30 EST


From: Kunwu Chan <chentao@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Kunwu Chan <chentao@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://msgid.link/20231204023223.2447523-1-chentao@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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