From: Masami Hiramatsu mhiramat@kernel.org
[ Upstream commit 2f706e0e5e263c0d204e37ea496cbb0e98aac2d2 ]
Fix can_boost() to identify indirect jmp and others using range case correctly.
Since the condition in switch statement is opcode & 0xf0, it can not evaluate to 0xff case. This should be under the 0xf0 case. However, there is no reason to use the conbinations of the bit-masked condition and lower bit checking.
Use range case to clean up the switch statement too.
Fixes: 6256e668b7 ("x86/kprobes: Use int3 instead of debug trap for single-step") Reported-by: Colin Ian King colin.king@canonical.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Link: https://lore.kernel.org/r/161666692308.1120877.4675552834049546493.stgit@dev... Signed-off-by: Li Huafei lihuafei1@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/kprobes/core.c | 44 ++++++++++++++++++----------------------- 1 file changed, 20 insertions(+), 24 deletions(-)
--- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -165,32 +165,28 @@ int can_boost(struct insn *insn, void *a
opcode = insn->opcode.bytes[0];
- switch (opcode & 0xf0) { - case 0x60: - /* can't boost "bound" */ - return (opcode != 0x62); - case 0x70: - return 0; /* can't boost conditional jump */ - case 0x90: - return opcode != 0x9a; /* can't boost call far */ - case 0xc0: - /* can't boost software-interruptions */ - return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; - case 0xd0: - /* can boost AA* and XLAT */ - return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); - case 0xe0: - /* can boost in/out and absolute jmps */ - return ((opcode & 0x04) || opcode == 0xea); - case 0xf0: - /* clear and set flags are boostable */ - return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); - case 0xff: - /* indirect jmp is boostable */ + switch (opcode) { + case 0x62: /* bound */ + case 0x70 ... 0x7f: /* Conditional jumps */ + case 0x9a: /* Call far */ + case 0xc0 ... 0xc1: /* Grp2 */ + case 0xcc ... 0xce: /* software exceptions */ + case 0xd0 ... 0xd3: /* Grp2 */ + case 0xd6: /* (UD) */ + case 0xd8 ... 0xdf: /* ESC */ + case 0xe0 ... 0xe3: /* LOOP*, JCXZ */ + case 0xe8 ... 0xe9: /* near Call, JMP */ + case 0xeb: /* Short JMP */ + case 0xf0 ... 0xf4: /* LOCK/REP, HLT */ + case 0xf6 ... 0xf7: /* Grp3 */ + case 0xfe: /* Grp4 */ + /* ... are not boostable */ + return 0; + case 0xff: /* Grp5 */ + /* Only indirect jmp is boostable */ return X86_MODRM_REG(insn->modrm.bytes[0]) == 4; default: - /* call is not boostable */ - return opcode != 0x9a; + return 1; } }