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s390/kprobes: allow kprobes only on known instructions

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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>
This commit is contained in:
Heiko Carstens 2013-09-13 14:14:10 +02:00 committed by Martin Schwidefsky
parent a882b3b067
commit 1ffa11abfe
3 changed files with 9 additions and 1 deletions
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6
arch/s390/include/asm/dis.h
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@ -42,5 +42,11 @@ static inline int insn_length(unsigned char code)
void show_code(struct pt_regs *regs); void show_code(struct pt_regs *regs);
void print_fn_code(unsigned char *code, unsigned long len); void print_fn_code(unsigned char *code, unsigned long len);
int insn_to_mnemonic(unsigned char *instruction, char *buf, unsigned int 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__ */ #endif /* __ASM_S390_DIS_H__ */

2
arch/s390/kernel/dis.c
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@ -1586,7 +1586,7 @@ static unsigned int extract_operand(unsigned char *code,
return val; 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 opfrag = code[1];
unsigned char opmask; unsigned char opmask;

2
arch/s390/kernel/kprobes.c
View File

@ -60,6 +60,8 @@ struct kprobe_insn_cache kprobe_dmainsn_slots = {
static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn) static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
{ {
if (!is_known_insn((unsigned char *)insn))
return -EINVAL;
switch (insn[0] >> 8) { switch (insn[0] >> 8) {
case 0x0c: /* bassm */ case 0x0c: /* bassm */
case 0x0b: /* bsm */ case 0x0b: /* bsm */