4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Masami Hiramatsu mhiramat@kernel.org
[ 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@kernel.org Cc: Ananth N Mavinakayanahalli ananth@linux.vnet.ibm.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Anil S Keshavamurthy anil.s.keshavamurthy@intel.com Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: David S . Miller davem@davemloft.net Cc: Denys Vlasenko dvlasenk@redhat.com Cc: H. Peter Anvin hpa@zytor.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Ye Xiaolong xiaolong.ye@intel.com Link: http://lkml.kernel.org/r/149076340615.22469.14066273186134229909.stgit@devbo... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -199,6 +199,8 @@ 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;