[PATCH] arm64: mm: use u32 for FDT size in fixmap_remap_fdt()

[Sang-Heon Jeon <ekffu200098@gmail.com>]

fixmap_remap_fdt() uses a signed int for the FDT size, so a malformed
totalsize bigger than INT_MAX wrongly passes the MAX_FDT_SIZE check.
Then create_mapping_noalloc() is called with a huge size and triggers
a BUG_ON() in the MMU code, with no diagnostic about the malformed FDT.

Change the FDT size from int to u32, which is the return type of
fdt_totalsize(). So a malformed totalsize no longer wrongly passes the
MAX_FDT_SIZE check, and setup_machine_fdt() prints a pr_crit
diagnostic for it, not a BUG_ON in the MMU code.

Fixes: 61bd93ce801b ("arm64: use fixmap region for permanent FDT mapping")
Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 arch/arm64/include/asm/mmu.h | 2 +-
 arch/arm64/kernel/setup.c    | 4 ++--
 arch/arm64/mm/fixmap.c       | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 5e1211c540ab..a6b388ef4c3f 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -68,7 +68,7 @@ extern void create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 			       unsigned long virt, phys_addr_t size,
 			       pgprot_t prot, bool page_mappings_only);
-extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot);
+extern void *fixmap_remap_fdt(phys_addr_t dt_phys, u32 *size, pgprot_t prot);
 extern void mark_linear_text_alias_ro(void);
 extern int split_kernel_leaf_mapping(unsigned long start, unsigned long end);
 extern void linear_map_maybe_split_to_ptes(void);
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 23c05dc7a8f2..7cabac0546dc 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -169,7 +169,7 @@ static void __init smp_build_mpidr_hash(void)
 
 static void __init setup_machine_fdt(phys_addr_t dt_phys)
 {
-	int size = 0;
+	u32 size = 0;
 	void *dt_virt = fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL);
 	const char *name;
 
@@ -182,7 +182,7 @@ static void __init setup_machine_fdt(phys_addr_t dt_phys)
 	 */
 	if (!early_init_dt_scan(dt_virt, dt_phys)) {
 		pr_crit("\n"
-			"Error: invalid device tree blob: PA=%pa, VA=%px, size=%d bytes\n"
+			"Error: invalid device tree blob: PA=%pa, VA=%px, size=%u bytes\n"
 			"The dtb must be 8-byte aligned and must not exceed 2 MB in size.\n"
 			"\nPlease check your bootloader.\n",
 			&dt_phys, dt_virt, size);
diff --git a/arch/arm64/mm/fixmap.c b/arch/arm64/mm/fixmap.c
index c5c5425791da..c692e6ac2405 100644
--- a/arch/arm64/mm/fixmap.c
+++ b/arch/arm64/mm/fixmap.c
@@ -134,11 +134,11 @@ void __set_fixmap(enum fixed_addresses idx,
 	}
 }
 
-void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
+void *__init fixmap_remap_fdt(phys_addr_t dt_phys, u32 *size, pgprot_t prot)
 {
 	const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
 	phys_addr_t dt_phys_base;
-	int offset;
+	u32 offset;
 	void *dt_virt;
 
 	/*
-- 
2.43.0