On Fri, Sep 02, 2022 at 08:06:28AM +0000, Christophe Leroy wrote:

Le 01/09/2022 à 21:20, Peter Zijlstra a écrit :

quoted

On Mon, Aug 29, 2022 at 11:22:15AM +0530, Sathvika Vasireddy wrote:

quoted

From: Christophe Leroy <redacted>

find_insn() will return NULL in case of failure. Check insn in order
to avoid a kernel Oops for NULL pointer dereference.

Signed-off-by: Christophe Leroy <redacted>
---
  tools/objtool/check.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 91678252a9b6..ed2fdfeb1d9c 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c

@@ -205,7 +205,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
  		return false;
  
  	insn = find_insn(file, func->sec, func->offset);
-	if (!insn->func)
+	if (!insn || !insn->func)
  		return false;

I suppose this is ok, but how can the lookup for func->sec, func->offset
*not* find an instruction ?!

That happened to me at the begining when the port to powerpc was not 
fully functionnal.

I guess that could also happen with a corrupted object file so better 
safe than sorry.

Fair enough.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>