[PATCH tip v7 2/7] MIPS: Differentiate between 32 and 64 bit ELF header

From: Daniel Wagner
Date: Fri Jan 29 2016 - 09:03:43 EST


Depending on the configuration either the 32 or 64 bit version of
elf_check_arch() is defined. parse_crash_elf32_headers() does
some basic verification of the ELF header via elf_check_arch().
parse_crash_elf64_headers() does it via vmcore_elf64_check_arch()
which expands to the same elf_check_check().

In file included from include/linux/elf.h:4:0,
from fs/proc/vmcore.c:13:
fs/proc/vmcore.c: In function 'parse_crash_elf64_headers':
>> arch/mips/include/asm/elf.h:228:23: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
struct elfhdr *__h = (hdr); \
^
include/linux/crash_dump.h:41:37: note: in expansion of macro 'elf_check_arch'
#define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
^
fs/proc/vmcore.c:1015:4: note: in expansion of macro 'vmcore_elf64_check_arch'
!vmcore_elf64_check_arch(&ehdr) ||
^

Since the MIPS ELF header for 32 bit and 64 bit differ we need
to check accordingly.

Signed-off-by: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
---
arch/mips/include/asm/elf.h | 68 ++++++++++++++++++++++++---------------------
1 file changed, 37 insertions(+), 31 deletions(-)

diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index b01a6ff..e311d60 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -205,27 +205,10 @@ struct mips_elf_abiflags_v0 {
#define MIPS_ABI_FP_64 6 /* -mips32r2 -mfp64 */
#define MIPS_ABI_FP_64A 7 /* -mips32r2 -mfp64 -mno-odd-spreg */

-#ifdef CONFIG_32BIT
-
-/*
- * In order to be sure that we don't attempt to execute an O32 binary which
- * requires 64 bit FP (FR=1) on a system which does not support it we refuse
- * to execute any binary which has bits specified by the following macro set
- * in its ELF header flags.
- */
-#ifdef CONFIG_MIPS_O32_FP64_SUPPORT
-# define __MIPS_O32_FP64_MUST_BE_ZERO 0
-#else
-# define __MIPS_O32_FP64_MUST_BE_ZERO EF_MIPS_FP64
-#endif
-
-/*
- * This is used to ensure we don't load something for the wrong architecture.
- */
-#define elf_check_arch(hdr) \
+#define elf_check_arch_32(hdr) \
({ \
int __res = 1; \
- struct elfhdr *__h = (hdr); \
+ Elf32_Ehdr *__h = (hdr); \
\
if (__h->e_machine != EM_MIPS) \
__res = 0; \
@@ -242,6 +225,40 @@ struct mips_elf_abiflags_v0 {
__res; \
})

+#define elf_check_arch_64(hdr) \
+({ \
+ int __res = 1; \
+ Elf64_Ehdr *__h = (hdr); \
+ \
+ if (__h->e_machine != EM_MIPS) \
+ __res = 0; \
+ if (__h->e_ident[EI_CLASS] != ELFCLASS64) \
+ __res = 0; \
+ \
+ __res; \
+})
+
+#define vmcore_elf64_check_arch(x) (elf_check_arch_64(x) || vmcore_elf_check_arch_cross(x))
+
+#ifdef CONFIG_32BIT
+
+/*
+ * In order to be sure that we don't attempt to execute an O32 binary which
+ * requires 64 bit FP (FR=1) on a system which does not support it we refuse
+ * to execute any binary which has bits specified by the following macro set
+ * in its ELF header flags.
+ */
+#ifdef CONFIG_MIPS_O32_FP64_SUPPORT
+# define __MIPS_O32_FP64_MUST_BE_ZERO 0
+#else
+# define __MIPS_O32_FP64_MUST_BE_ZERO EF_MIPS_FP64
+#endif
+
+/*
+ * This is used to ensure we don't load something for the wrong architecture.
+ */
+#define elf_check_arch(x) elf_check_arch_32(x)
+
/*
* These are used to set parameters in the core dumps.
*/
@@ -253,18 +270,7 @@ struct mips_elf_abiflags_v0 {
/*
* This is used to ensure we don't load something for the wrong architecture.
*/
-#define elf_check_arch(hdr) \
-({ \
- int __res = 1; \
- struct elfhdr *__h = (hdr); \
- \
- if (__h->e_machine != EM_MIPS) \
- __res = 0; \
- if (__h->e_ident[EI_CLASS] != ELFCLASS64) \
- __res = 0; \
- \
- __res; \
-})
+#define elf_check_arch(x) elf_check_arch_64(x)

/*
* These are used to set parameters in the core dumps.
--
2.5.0