From 4d409ca3e5107a1b300d0f36550d61c5da4fd8a7 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 9 Mar 2022 10:50:32 -0800 Subject: [PATCH] MIPS: boot/compressed: Use array reference for image bounds As done with other image addresses in other architectures, use an explicit flexible array instead of "address of char", which can trip bounds checking done by the compiler. Found when building with -Warray-bounds: In file included from ./include/linux/byteorder/little_endian.h:5, from ./arch/mips/include/uapi/asm/byteorder.h:15, from ./arch/mips/include/asm/bitops.h:21, from ./include/linux/bitops.h:33, from ./include/linux/kernel.h:22, from arch/mips/boot/compressed/decompress.c:13: arch/mips/boot/compressed/decompress.c: In function 'decompress_kernel': ./include/asm-generic/unaligned.h:14:8: warning: array subscript -1 is outside array bounds of 'unsigned char[1]' [-Warray-bounds] 14 | __pptr->x; \ | ~~~~~~^~~ ./include/uapi/linux/byteorder/little_endian.h:35:51: note: in definition of macro '__le32_to_cpu' 35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x)) | ^ ./include/asm-generic/unaligned.h:32:21: note: in expansion of macro '__get_unaligned_t' 32 | return le32_to_cpu(__get_unaligned_t(__le32, p)); | ^~~~~~~~~~~~~~~~~ arch/mips/boot/compressed/decompress.c:29:37: note: while referencing '__image_end' 29 | extern unsigned char __image_begin, __image_end; | ^~~~~~~~~~~ Cc: Thomas Bogendoerfer Cc: Randy Dunlap Cc: linux-mips@vger.kernel.org Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Signed-off-by: Thomas Bogendoerfer --- arch/mips/boot/compressed/decompress.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c index aae1346a509a..5b38a802e101 100644 --- a/arch/mips/boot/compressed/decompress.c +++ b/arch/mips/boot/compressed/decompress.c @@ -26,7 +26,7 @@ unsigned long free_mem_ptr; unsigned long free_mem_end_ptr; /* The linker tells us where the image is. */ -extern unsigned char __image_begin, __image_end; +extern unsigned char __image_begin[], __image_end[]; /* debug interfaces */ #ifdef CONFIG_DEBUG_ZBOOT @@ -91,9 +91,9 @@ void decompress_kernel(unsigned long boot_heap_start) { unsigned long zimage_start, zimage_size; - zimage_start = (unsigned long)(&__image_begin); - zimage_size = (unsigned long)(&__image_end) - - (unsigned long)(&__image_begin); + zimage_start = (unsigned long)(__image_begin); + zimage_size = (unsigned long)(__image_end) - + (unsigned long)(__image_begin); puts("zimage at: "); puthex(zimage_start); @@ -121,7 +121,7 @@ void decompress_kernel(unsigned long boot_heap_start) dtb_size = fdt_totalsize((void *)&__appended_dtb); /* last four bytes is always image size in little endian */ - image_size = get_unaligned_le32((void *)&__image_end - 4); + image_size = get_unaligned_le32((void *)__image_end - 4); /* The device tree's address must be properly aligned */ image_size = ALIGN(image_size, STRUCT_ALIGNMENT);