[PATCH] x86/dumpstack: Don't mention RIP in "Code:"

From: Jiri Slaby
Date: Tue Sep 06 2022 - 03:11:34 EST


Commit 238c91115cd0 ("x86/dumpstack: Fix misleading instruction pointer
error message") changed the "Code:" line in bug reports when RIP is an
invalid pointer. In particular, the report currently says (for example):

BUG: kernel NULL pointer dereference, address: 0000000000000000
...
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.

That "Unable to access opcode bytes at RIP 0xffffffffffffffd6." is
quite confusing as RIP value is 0, not -42. That -42 comes from
"regs->ip - PROLOGUE_SIZE", because Code is dumped with some prologue
(and epilogue).

So do not mention "RIP" on this line in this context.

Cc: Mark Mossberg <mark.mossberg@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
arch/x86/kernel/dumpstack.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index afae4dd77495..b3dba35f466e 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -128,7 +128,7 @@ void show_opcodes(struct pt_regs *regs, const char *loglvl)
/* No access to the user space stack of other tasks. Ignore. */
break;
default:
- printk("%sCode: Unable to access opcode bytes at RIP 0x%lx.\n",
+ printk("%sCode: Unable to access opcode bytes at 0x%lx.\n",
loglvl, prologue);
break;
}
--
2.37.3