From 50cf9c6ca2674459626a8e47c88b8229097b9221 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 28 Oct 2020 23:31:10 +0900 Subject: [PATCH] x86/kprobes: Restore BTF if the single-stepping is cancelled [ Upstream commit 78ff2733ff352175eb7f4418a34654346e1b6cd2 ] Fix to restore BTF if single-stepping causes a page fault and it is cancelled. Usually the BTF flag was restored when the single stepping is done (in resume_execution()). However, if a page fault happens on the single stepping instruction, the fault handler is invoked and the single stepping is cancelled. Thus, the BTF flag is not restored. Fixes: 1ecc798c6764 ("x86: debugctlmsr kprobes") Signed-off-by: Masami Hiramatsu Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/160389546985.106936.12727996109376240993.stgit@devnote2 Signed-off-by: Sasha Levin --- arch/x86/kernel/kprobes/core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 547c7abb39f5..39f7d8c3c064 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -937,6 +937,11 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) * So clear it by resetting the current kprobe: */ regs->flags &= ~X86_EFLAGS_TF; + /* + * Since the single step (trap) has been cancelled, + * we need to restore BTF here. + */ + restore_btf(); /* * If the TF flag was set before the kprobe hit,