Messages in this thread Patch in this message | | | Date | Mon, 3 Sep 2018 06:15:55 -0700 | From | tip-bot for Jann Horn <> | Subject | [tip:x86/core] x86/kprobes: Refactor kprobes_fault() like kprobe_exceptions_notify() |
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Commit-ID: a980c0ef9f6d8c45445d6ed0f5836bb6941c8c91 Gitweb: https://git.kernel.org/tip/a980c0ef9f6d8c45445d6ed0f5836bb6941c8c91 Author: Jann Horn <jannh@google.com> AuthorDate: Tue, 28 Aug 2018 22:14:15 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Mon, 3 Sep 2018 15:12:08 +0200
x86/kprobes: Refactor kprobes_fault() like kprobe_exceptions_notify()
This is an extension of commit b506a9d08bae ("x86: code clarification patch to Kprobes arch code"). As that commit explains, even though kprobe_running() can't be called with preemption enabled, preemption does not need to be disabled. If preemption is enabled, then this can't be originate from a kprobe.
Also, use X86_TRAP_PF instead of 14.
Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Kees Cook <keescook@chromium.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: kernel-hardening@lists.openwall.com Cc: dvyukov@google.com Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: Borislav Petkov <bp@alien8.de> Link: https://lkml.kernel.org/r/20180828201421.157735-2-jannh@google.com
--- arch/x86/mm/fault.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 47bebfe6efa7..d99edb2d567b 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -44,17 +44,19 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr) static nokprobe_inline int kprobes_fault(struct pt_regs *regs) { - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (kprobes_built_in() && !user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, 14)) - ret = 1; - preempt_enable(); - } - - return ret; + if (!kprobes_built_in()) + return 0; + if (user_mode(regs)) + return 0; + /* + * To be potentially processing a kprobe fault and to be allowed to call + * kprobe_running(), we have to be non-preemptible. + */ + if (preemptible()) + return 0; + if (!kprobe_running()) + return 0; + return kprobe_fault_handler(regs, X86_TRAP_PF); } /*
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