[PATCH v16 10/20] unwind_user/sframe: Remove .sframe section on detected corruption

[Jens Remus]

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

To avoid continued attempted use of a bad .sframe section, remove it
on demand when the first sign of corruption is detected.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Reviewed-by: Indu Bhagat <ibhagatgnu@xxxxxxxxx>
Signed-off-by: Jens Remus <jremus@xxxxxxxxxxxxx>
---

Notes (jremus):
    Changes in v15:
    - sframe_find(): Align to normalized error code usage and remove .sframe
      for all but ENOENT.  Also remove if user_read_access_begin() fails.

 kernel/unwind/sframe.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 41ece3ca62a1..e0eb2adf5a07 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -371,10 +371,15 @@ int sframe_find(unsigned long ip, struct unwind_user_frame *frame)
 			ret = __find_fre(sec, &fde, ip, frame);
 	}
 
+end:
+	if (ret && ret != -ENOENT)
+		WARN_ON_ONCE(sframe_remove_section(sec->sframe_start));
+
 	return ret;
 
 Efault:
-	return -EFAULT;
+	ret = -EFAULT;
+	goto end;
 }
 
 static void free_section(struct sframe_section *sec)
-- 
2.51.0