4.16-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
[ 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@kernel.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Oleg Nesterov oleg@redhat.com Cc: Ricardo Neri ricardo.neri-calderon@linux.intel.com Cc: Francis Deslauriers francis.deslauriers@efficios.com Cc: Alexei Starovoitov ast@kernel.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Andy Lutomirski luto@kernel.org Cc: "H . Peter Anvin" hpa@zytor.com Cc: Yonghong Song yhs@fb.com Cc: Borislav Petkov bp@suse.de Cc: Linus Torvalds torvalds@linux-foundation.org Cc: "David S . Miller" davem@davemloft.net Link: https://lkml.kernel.org/r/152587072544.17316.5950935243917346341.stgit@devbo... Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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