s390/kprobes: allow kprobes only on known instructions
Since we have an in-kernel disassembler we can make sure that
there won't be any kprobes set on random data.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/dis.h b/arch/s390/include/asm/dis.h
index 4d0dffc..04a83f5 100644
--- a/arch/s390/include/asm/dis.h
+++ b/arch/s390/include/asm/dis.h
@@ -42,5 +42,11 @@
void show_code(struct pt_regs *regs);
void print_fn_code(unsigned char *code, unsigned long len);
int insn_to_mnemonic(unsigned char *instruction, char *buf, unsigned int len);
+struct s390_insn *find_insn(unsigned char *code);
+
+static inline int is_known_insn(unsigned char *code)
+{
+ return !!find_insn(code);
+}
#endif /* __ASM_S390_DIS_H__ */
diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c
index ce554f3..993efe6 100644
--- a/arch/s390/kernel/dis.c
+++ b/arch/s390/kernel/dis.c
@@ -1586,7 +1586,7 @@
return val;
}
-static struct s390_insn *find_insn(unsigned char *code)
+struct s390_insn *find_insn(unsigned char *code)
{
unsigned char opfrag = code[1];
unsigned char opmask;
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index c52fdf2..59a9c35 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -60,6 +60,8 @@
static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
{
+ if (!is_known_insn((unsigned char *)insn))
+ return -EINVAL;
switch (insn[0] >> 8) {
case 0x0c: /* bassm */
case 0x0b: /* bsm */