4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> [ Upstream commit bd0b90676c30fe640e7ead919b3e38846ac88ab7 ] Fix the kprobe-booster not to boost far call instruction, because a call may store the address in the single-step execution buffer to the stack, which should be modified after single stepping. Currently, this instruction will be filtered as not boostable in resume_execution(), so this is not a critical issue. Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: David S . Miller <davem@xxxxxxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ye Xiaolong <xiaolong.ye@xxxxxxxxx> Link: http://lkml.kernel.org/r/149076340615.22469.14066273186134229909.stgit@devbox Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/kprobes/core.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -196,6 +196,8 @@ retry: return (opcode != 0x62 && opcode != 0x67); 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;