diff options
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 48 |
1 files changed, 39 insertions, 9 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 70982e725fd7..c65ca556005a 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -252,7 +252,28 @@ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long add return __recover_probed_insn(buf, addr); } -/* Check if paddr is at an instruction boundary */ +/* Check if insn is INT or UD */ +static inline bool is_exception_insn(struct insn *insn) +{ + /* UD uses 0f escape */ + if (insn->opcode.bytes[0] == 0x0f) { + /* UD0 / UD1 / UD2 */ + return insn->opcode.bytes[1] == 0xff || + insn->opcode.bytes[1] == 0xb9 || + insn->opcode.bytes[1] == 0x0b; + } + + /* INT3 / INT n / INTO / INT1 */ + return insn->opcode.bytes[0] == 0xcc || + insn->opcode.bytes[0] == 0xcd || + insn->opcode.bytes[0] == 0xce || + insn->opcode.bytes[0] == 0xf1; +} + +/* + * Check if paddr is at an instruction boundary and that instruction can + * be probed + */ static bool can_probe(unsigned long paddr) { unsigned long addr, __addr, offset = 0; @@ -291,6 +312,22 @@ static bool can_probe(unsigned long paddr) #endif addr += insn.length; } + + /* Check if paddr is at an instruction boundary */ + if (addr != paddr) + return false; + + __addr = recover_probed_instruction(buf, addr); + if (!__addr) + return false; + + if (insn_decode_kernel(&insn, (void *)__addr) < 0) + return false; + + /* INT and UD are special and should not be kprobed */ + if (is_exception_insn(&insn)) + return false; + if (IS_ENABLED(CONFIG_CFI_CLANG)) { /* * The compiler generates the following instruction sequence @@ -305,13 +342,6 @@ static bool can_probe(unsigned long paddr) * Also, these movl and addl are used for showing expected * type. So those must not be touched. */ - __addr = recover_probed_instruction(buf, addr); - if (!__addr) - return false; - - if (insn_decode_kernel(&insn, (void *)__addr) < 0) - return false; - if (insn.opcode.value == 0xBA) offset = 12; else if (insn.opcode.value == 0x3) @@ -325,7 +355,7 @@ static bool can_probe(unsigned long paddr) } out: - return (addr == paddr); + return true; } /* If x86 supports IBT (ENDBR) it must be skipped. */ |