linux-kernel - [stable 4.9.y 2/4] scripts/gdb: lx-dmesg: cast log

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Date:   Thu,  7 Jan 2021 14:52:27 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Leonard Crestez <leonard.crestez@....com>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        Jason Wessel <jason.wessel@...driver.com>,
        Kieran Bingham <kieran@...uared.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Kieran Bingham <kieran@...uared.org.uk>,
        André Draszik <git@...red.net>,
        Du Changbin <changbin.du@...il.com>
Subject: [stable 4.9.y 2/4] scripts/gdb: lx-dmesg: cast log_buf to void* for addr fetch

From: Leonard Crestez <leonard.crestez@....com>

commit c454756f47277b651ad41a5a163499294529e35d upstream

In some cases it is possible for the str() conversion here to throw
encoding errors because log_buf might not point to valid ascii.  For
example:

  (gdb) python print str(gdb.parse_and_eval("log_buf"))
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  UnicodeEncodeError: 'ascii' codec can't encode character u'\u0303' in
  	position 24: ordinal not in range(128)

Avoid this by explicitly casting to (void *) inside the gdb expression.

Link: http://lkml.kernel.org/r/ba6f85dbb02ca980ebd0e2399b0649423399b565.1498481469.git.leonard.crestez@nxp.com
Signed-off-by: Leonard Crestez <leonard.crestez@....com>
Reviewed-by: Jan Kiszka <jan.kiszka@...mens.com>
Cc: Jason Wessel <jason.wessel@...driver.com>
Cc: Kieran Bingham <kieran@...uared.org.uk>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 scripts/gdb/linux/dmesg.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py
index 5afd1098e33a..f5a030333dfd 100644
--- a/scripts/gdb/linux/dmesg.py
+++ b/scripts/gdb/linux/dmesg.py
@@ -24,7 +24,7 @@ class LxDmesg(gdb.Command):
 
     def invoke(self, arg, from_tty):
         log_buf_addr = int(str(gdb.parse_and_eval(
-            "'printk.c'::log_buf")).split()[0], 16)
+            "(void *)'printk.c'::log_buf")).split()[0], 16)
         log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx"))
         log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx"))
         log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len"))
-- 
2.25.1