Thread (3 messages) 3 messages, 2 authors, 2023-12-04

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

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2023-12-01 10:17:34
Also in: lkml

Kunwu Chan [off-list ref] writes:
quoted hunk ↗ jump to hunk
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 <redacted>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Kunwu Chan <redacted>
---
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);
It would be nice to avoid two calls to panic. Can you reorganise the
logic so that there's only one? Initialising new to NULL might help.

cheers
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