[PATCH 2/8] powerpc/kexec_file: Fix null-ptr-def in extra size calculation

[Jinjie Ruan]

A static Sashiko AI review identified a potential NULL pointer
dereference in kexec_extra_fdt_size_ppc64().

On platforms without any reserved memory regions,
get_reserved_memory_ranges() can return 0 while leaving 'rmem'
unallocated as NULL. Passing it directly leads to a kernel panic when
evaluating 'rmem->nr_ranges'.

Add a NULL check for 'rmem' to prevent this crash.

Cc: Sourabh Jain <sourabhjain at linux.ibm.com>
Cc: Hari Bathini <hbathini at linux.ibm.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: stable at vger.kernel.org
Fixes: 0d3ff067331e ("powerpc/kexec_file: fix extra size calculation for kexec FDT")
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 arch/powerpc/kexec/file_load_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 8c72e12ea44e..6075b1c88511 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -664,7 +664,7 @@ unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image, struct crash_mem *
 		extra_size += (cpu_nodes - boot_cpu_node_count) * cpu_node_size();
 
 	/* Consider extra space for reserved memory ranges if any */
-	if (rmem->nr_ranges > 0)
+	if (rmem && rmem->nr_ranges > 0)
 		extra_size += sizeof(struct fdt_reserve_entry) * rmem->nr_ranges;
 
 	return extra_size + kdump_extra_fdt_size_ppc64(image, cpu_nodes);
-- 
2.34.1