powerpc/mm: Fix null-pointer dereference in pgtable_cache_add

[ 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@csgroup.eu>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231204023223.2447523-1-chentao@kylinos.cn
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/mm/init-common.c b/arch/powerpc/mm/init-common.c
index 119ef49..d3a7726 100644 (file)
--- a/arch/powerpc/mm/init-common.c
+++ b/arch/powerpc/mm/init-common.c
@@ -126,7 +126,7 @@ 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
@@ -139,7 +139,8 @@ 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);