4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> [ Upstream commit 13ebe18c94f5b0665c01ae7fad2717ae959f4212 ] Since MOV SS and POP SS instructions will delay the exceptions until the next instruction is executed, single-stepping on it by uprobes must be prohibited. uprobe already rejects probing on POP SS (0x1f), but allows probing on MOV SS (0x8e and reg == 2). This checks the target instruction and if it is MOV SS or POP SS, returns -ENOTSUPP to reject probing. Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx> Cc: Francis Deslauriers <francis.deslauriers@xxxxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: "H . Peter Anvin" <hpa@xxxxxxxxx> Cc: Yonghong Song <yhs@xxxxxx> Cc: Borislav Petkov <bp@xxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: "David S . Miller" <davem@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/152587072544.17316.5950935243917346341.stgit@devbox Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/uprobes.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -299,6 +299,10 @@ static int uprobe_init_insn(struct arch_ if (is_prefix_bad(insn)) return -ENOTSUPP; + /* We should not singlestep on the exception masking instructions */ + if (insn_masking_exception(insn)) + return -ENOTSUPP; + if (x86_64) good_insns = good_insns_64; else
