m68k: Process bootinfo records before saving them

[ Upstream commit 7c236d9 ]

The RNG seed boot record is memzeroed after processing, in order to
preserve forward secrecy. By saving the bootinfo for procfs prior to
that, forward secrecy is violated, since it becomes possible to recover
past states. So, save the bootinfo block only after first processing
them.

Fixes: a1ee38a ("m68k: virt: Use RNG seed from bootinfo block")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20220927130835.1629806-1-Jason@zx2c4.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/m68k/kernel/setup_mm.c

@@ -109,10 +109,9 @@ extern void paging_init(void);
 
 static void __init m68k_parse_bootinfo(const struct bi_record *record)
 {
+	const struct bi_record *first_record = record;
 	uint16_t tag;
 
-	save_bootinfo(record);
-
 	while ((tag = be16_to_cpu(record->tag)) != BI_LAST) {
 		int unknown = 0;
 		const void *data = record->data;
@@ -182,6 +181,8 @@ static void __init m68k_parse_bootinfo(const struct bi_record *record)
 		record = (struct bi_record *)((unsigned long)record + size);
 	}
 
+	save_bootinfo(first_record);
+
 	m68k_realnum_memory = m68k_num_memory;
 #ifdef CONFIG_SINGLE_MEMORY_CHUNK
 	if (m68k_num_memory > 1) {