4.16-stable review patch. If anyone has any objections, please let me know.
------------------ From: Masami Hiramatsu <[email protected]> [ 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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Oleg Nesterov <[email protected]> Cc: Ricardo Neri <[email protected]> Cc: Francis Deslauriers <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: "H . Peter Anvin" <[email protected]> Cc: Yonghong Song <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: "David S . Miller" <[email protected]> Link: https://lkml.kernel.org/r/152587072544.17316.5950935243917346341.stgit@devbox Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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
