kprobes/x86: Fix to set RWX bits correctly before releasing trampoline (c93f5cf5) · Commits · 戴 / test

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. Link: http://lkml.kernel.org/r/149570868652.3518.14120169373590420503.stgit@devbox Signed-off-by:

Masami Hiramatsu <mhiramat@kernel.org> Fixes: ("kprobes/x86: Set kprobes pages read-only") Signed-off-by:

Steven Rostedt (VMware) <rostedt@goodmis.org>

arch/x86/kernel/kprobes/core.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}

		static int arch_copy_kprobe(struct kprobe *p)
		{
		struct insn insn;

kernel/kprobes.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -122,7 +122,7 @@ static void *alloc_insn_page(void)
		return module_alloc(PAGE_SIZE);
		}

		static void free_insn_page(void *page)
		void __weak free_insn_page(void *page)
		{
		module_memfree(page);
		}

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