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authorMatthew Leach <matthew.leach@arm.com>2013-10-11 14:52:14 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2013-10-25 15:59:37 +0100
commita1d5ebaf8ccdd100f45042ce32c591867de04ac3 (patch)
tree8f47a40eabb63ca19ec96936fd808537824c0b25
parent55b89540b0d8d031f90e3d711ec0df3f797ecc61 (diff)
arm64: big-endian: don't treat code as data when copying sigret code
Currently the sigreturn compat code is copied to an offset in the vectors table. When using a BE kernel this data will be stored in the wrong endianess so when returning from a signal on a 32-bit BE system, arbitrary code will be executed. Instead of declaring the code inside a struct and copying that, use the assembler's .byte directives to store the code in the correct endianess regardless of platform endianess. Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Matthew Leach <matthew.leach@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/kernel/kuser32.S42
-rw-r--r--arch/arm64/kernel/signal32.c28
-rw-r--r--arch/arm64/kernel/vdso.c5
3 files changed, 46 insertions, 29 deletions
diff --git a/arch/arm64/kernel/kuser32.S b/arch/arm64/kernel/kuser32.S
index 8b69ecb1d8bc..1e4905d52d30 100644
--- a/arch/arm64/kernel/kuser32.S
+++ b/arch/arm64/kernel/kuser32.S
@@ -27,6 +27,9 @@
*
* See Documentation/arm/kernel_user_helpers.txt for formal definitions.
*/
+
+#include <asm/unistd32.h>
+
.align 5
.globl __kuser_helper_start
__kuser_helper_start:
@@ -75,3 +78,42 @@ __kuser_helper_version: // 0xffff0ffc
.word ((__kuser_helper_end - __kuser_helper_start) >> 5)
.globl __kuser_helper_end
__kuser_helper_end:
+
+/*
+ * AArch32 sigreturn code
+ *
+ * For ARM syscalls, the syscall number has to be loaded into r7.
+ * We do not support an OABI userspace.
+ *
+ * For Thumb syscalls, we also pass the syscall number via r7. We therefore
+ * need two 16-bit instructions.
+ */
+ .globl __aarch32_sigret_code_start
+__aarch32_sigret_code_start:
+
+ /*
+ * ARM Code
+ */
+ .byte __NR_compat_sigreturn, 0x70, 0xa0, 0xe3 // mov r7, #__NR_compat_sigreturn
+ .byte __NR_compat_sigreturn, 0x00, 0x00, 0xef // svc #__NR_compat_sigreturn
+
+ /*
+ * Thumb code
+ */
+ .byte __NR_compat_sigreturn, 0x27 // svc #__NR_compat_sigreturn
+ .byte __NR_compat_sigreturn, 0xdf // mov r7, #__NR_compat_sigreturn
+
+ /*
+ * ARM code
+ */
+ .byte __NR_compat_rt_sigreturn, 0x70, 0xa0, 0xe3 // mov r7, #__NR_compat_rt_sigreturn
+ .byte __NR_compat_rt_sigreturn, 0x00, 0x00, 0xef // svc #__NR_compat_rt_sigreturn
+
+ /*
+ * Thumb code
+ */
+ .byte __NR_compat_rt_sigreturn, 0x27 // svc #__NR_compat_rt_sigreturn
+ .byte __NR_compat_rt_sigreturn, 0xdf // mov r7, #__NR_compat_rt_sigreturn
+
+ .globl __aarch32_sigret_code_end
+__aarch32_sigret_code_end:
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index e393174fe859..e8772c07cf5c 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -100,34 +100,6 @@ struct compat_rt_sigframe {
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
-/*
- * For ARM syscalls, the syscall number has to be loaded into r7.
- * We do not support an OABI userspace.
- */
-#define MOV_R7_NR_SIGRETURN (0xe3a07000 | __NR_compat_sigreturn)
-#define SVC_SYS_SIGRETURN (0xef000000 | __NR_compat_sigreturn)
-#define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | __NR_compat_rt_sigreturn)
-#define SVC_SYS_RT_SIGRETURN (0xef000000 | __NR_compat_rt_sigreturn)
-
-/*
- * For Thumb syscalls, we also pass the syscall number via r7. We therefore
- * need two 16-bit instructions.
- */
-#define SVC_THUMB_SIGRETURN (((0xdf00 | __NR_compat_sigreturn) << 16) | \
- 0x2700 | __NR_compat_sigreturn)
-#define SVC_THUMB_RT_SIGRETURN (((0xdf00 | __NR_compat_rt_sigreturn) << 16) | \
- 0x2700 | __NR_compat_rt_sigreturn)
-
-const compat_ulong_t aarch32_sigret_code[6] = {
- /*
- * AArch32 sigreturn code.
- * We don't construct an OABI SWI - instead we just set the imm24 field
- * to the EABI syscall number so that we create a sane disassembly.
- */
- MOV_R7_NR_SIGRETURN, SVC_SYS_SIGRETURN, SVC_THUMB_SIGRETURN,
- MOV_R7_NR_RT_SIGRETURN, SVC_SYS_RT_SIGRETURN, SVC_THUMB_RT_SIGRETURN,
-};
-
static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
{
compat_sigset_t cset;
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 6a389dc1bd49..65d40cf6945a 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -58,7 +58,10 @@ static struct page *vectors_page[1];
static int alloc_vectors_page(void)
{
extern char __kuser_helper_start[], __kuser_helper_end[];
+ extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
+
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
+ int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
unsigned long vpage;
vpage = get_zeroed_page(GFP_ATOMIC);
@@ -72,7 +75,7 @@ static int alloc_vectors_page(void)
/* sigreturn code */
memcpy((void *)vpage + AARCH32_KERN_SIGRET_CODE_OFFSET,
- aarch32_sigret_code, sizeof(aarch32_sigret_code));
+ __aarch32_sigret_code_start, sigret_sz);
flush_icache_range(vpage, vpage + PAGE_SIZE);
vectors_page[0] = virt_to_page(vpage);