On Thu, May 25, 2017 at 07:38:17PM +0900, Masami Hiramatsu wrote: > Fix kprobes to set(recover) RWX bits correctly on trampoline > buffer before releasing it. Releasing readonly page to > module_memfree() crash the kernel. > > Without this fix, if kprobes user register a bunch of kprobes > in function body (since kprobes on function entry usually > use ftrace) and unregister it, kernel hits a BUG and crash. > > Signed-off-by: Masami Hiramatsu <[email protected]> > Fixes: d0381c81c2f7 ("kprobes/x86: Set kprobes pages read-only") > --- > arch/x86/kernel/kprobes/core.c | 9 +++++++++ > kernel/kprobes.c | 2 +- > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c > index 5b2bbfb..6b87780 100644 > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -52,6 +52,7 @@ > #include <linux/ftrace.h> > #include <linux/frame.h> > #include <linux/kasan.h> > +#include <linux/moduleloader.h> > > #include <asm/text-patching.h> > #include <asm/cacheflush.h> > @@ -417,6 +418,14 @@ static void prepare_boost(struct kprobe *p, struct insn > *insn) > } > } > > +/* Recover page to RW mode before releasing it */ > +void free_insn_page(void *page) > +{ > + set_memory_nx((unsigned long)page & PAGE_MASK, 1); > + set_memory_rw((unsigned long)page & PAGE_MASK, 1); > + module_memfree(page); > +}
Is this needed for all module_memfree() ? If so should / could it just do it for alloc users ? Luis
