[tip: core/kprobes] kprobes: Prevent probes in .noinstr.text section

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the core/kprobes branch of tip:

Commit-ID:     66e9b0717102507e64f638790eaece88765cc9e5
Gitweb:        https://git.kernel.org/tip/66e9b0717102507e64f638790eaece88765cc9e5
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Tue, 10 Mar 2020 14:04:34 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 19 May 2020 15:56:20 +02:00

kprobes: Prevent probes in .noinstr.text section

Instrumentation is forbidden in the .noinstr.text section. Make kprobes
respect this.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200505134100.179862032@xxxxxxxxxxxxx

---
 include/linux/module.h |  2 ++
 kernel/kprobes.c       | 18 ++++++++++++++++++
 kernel/module.c        |  3 +++
 3 files changed, 23 insertions(+)

diff --git a/include/linux/module.h b/include/linux/module.h
index 1192097..d849d06 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -458,6 +458,8 @@ struct module {
 	void __percpu *percpu;
 	unsigned int percpu_size;
 #endif
+	void *noinstr_text_start;
+	unsigned int noinstr_text_size;
 
 #ifdef CONFIG_TRACEPOINTS
 	unsigned int num_tracepoints;
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9eb5acf..3f310df 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2229,6 +2229,12 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
 	/* Symbols in __kprobes_text are blacklisted */
 	ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
 					(unsigned long)__kprobes_text_end);
+	if (ret)
+		return ret;
+
+	/* Symbols in noinstr section are blacklisted */
+	ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
+					(unsigned long)__noinstr_text_end);
 
 	return ret ? : arch_populate_kprobe_blacklist();
 }
@@ -2248,6 +2254,12 @@ static void add_module_kprobe_blacklist(struct module *mod)
 		end = start + mod->kprobes_text_size;
 		kprobe_add_area_blacklist(start, end);
 	}
+
+	start = (unsigned long)mod->noinstr_text_start;
+	if (start) {
+		end = start + mod->noinstr_text_size;
+		kprobe_add_area_blacklist(start, end);
+	}
 }
 
 static void remove_module_kprobe_blacklist(struct module *mod)
@@ -2265,6 +2277,12 @@ static void remove_module_kprobe_blacklist(struct module *mod)
 		end = start + mod->kprobes_text_size;
 		kprobe_remove_area_blacklist(start, end);
 	}
+
+	start = (unsigned long)mod->noinstr_text_start;
+	if (start) {
+		end = start + mod->noinstr_text_size;
+		kprobe_remove_area_blacklist(start, end);
+	}
 }
 
 /* Module notifier call back, checking kprobes on the module */
diff --git a/kernel/module.c b/kernel/module.c
index faf7337..72ed2b3 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3150,6 +3150,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
 	}
 #endif
 
+	mod->noinstr_text_start = section_objs(info, ".noinstr.text", 1,
+						&mod->noinstr_text_size);
+
 #ifdef CONFIG_TRACEPOINTS
 	mod->tracepoints_ptrs = section_objs(info, "__tracepoints_ptrs",
 					     sizeof(*mod->tracepoints_ptrs),