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* Re: [kees:format-security 2/3] arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments
       [not found] <531d3b0e.4MeVQMzUoamEWeW7%fengguang.wu@intel.com>
@ 2014-03-10 17:41 ` Kees Cook
  2014-03-11  9:59   ` Matt Fleming
  0 siblings, 1 reply; 3+ messages in thread
From: Kees Cook @ 2014-03-10 17:41 UTC (permalink / raw)
  To: Matt Fleming, Paul Mundt; +Cc: kbuild test robot, LKML

On Sun, Mar 9, 2014 at 9:09 PM, kbuild test robot
<fengguang.wu@intel.com> wrote:
> tree:   git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git format-security
> head:   78ac7178787f348d93ac16cda556265af4b8ce17
> commit: 3aac21c82091399e96c528c8ac4f337757d6e81b [2/3] Make all format string problems fail the build
> config: make ARCH=sh allnoconfig
>
> All error/warnings:
>
>    arch/sh/kernel/dumpstack.c: In function 'print_trace_address':
>>> arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments [-Werror=format-security]
>    cc1: all warnings being treated as errors
>
> vim +118 arch/sh/kernel/dumpstack.c
>
> 4e14dfc7 Matt Fleming 2009-08-07  102                                           context, &graph);
> 4e14dfc7 Matt Fleming 2009-08-07  103           }
> 4e14dfc7 Matt Fleming 2009-08-07  104   }
> 4e14dfc7 Matt Fleming 2009-08-07  105  }
> 4e14dfc7 Matt Fleming 2009-08-07  106
> 4e14dfc7 Matt Fleming 2009-08-07  107  static int print_trace_stack(void *data, char *name)
> 4e14dfc7 Matt Fleming 2009-08-07  108  {
> 4e14dfc7 Matt Fleming 2009-08-07  109   printk("%s <%s> ", (char *)data, name);
> 4e14dfc7 Matt Fleming 2009-08-07  110   return 0;
> 4e14dfc7 Matt Fleming 2009-08-07  111  }
> 4e14dfc7 Matt Fleming 2009-08-07  112
> 4e14dfc7 Matt Fleming 2009-08-07  113  /*
> 4e14dfc7 Matt Fleming 2009-08-07  114   * Print one address/symbol entries per line.
> 4e14dfc7 Matt Fleming 2009-08-07  115   */
> 4e14dfc7 Matt Fleming 2009-08-07  116  static void print_trace_address(void *data, unsigned long addr, int reliable)
> 4e14dfc7 Matt Fleming 2009-08-07  117  {
> 4e14dfc7 Matt Fleming 2009-08-07 @118   printk(data);

This needs to be "printk("%s", data);" so there is no chance of having
"data" interpreted as a format string itself.

Thanks!

-Kees

> 4e14dfc7 Matt Fleming 2009-08-07  119   printk_address(addr, reliable);
> 4e14dfc7 Matt Fleming 2009-08-07  120  }
> 4e14dfc7 Matt Fleming 2009-08-07  121
> 4e14dfc7 Matt Fleming 2009-08-07  122  static const struct stacktrace_ops print_trace_ops = {
> 4e14dfc7 Matt Fleming 2009-08-07  123   .stack = print_trace_stack,
> 4e14dfc7 Matt Fleming 2009-08-07  124   .address = print_trace_address,
> 4e14dfc7 Matt Fleming 2009-08-07  125  };
> 4e14dfc7 Matt Fleming 2009-08-07  126
>
> :::::: The code at line 118 was first introduced by commit
> :::::: 4e14dfc722b8e9e07a355f97aa60a3d9f0739071 sh: Use the generalized stacktrace ops
>
> :::::: TO: Matt Fleming <matt@console-pimps.org>
> :::::: CC: Paul Mundt <lethal@linux-sh.org>
>
> ---
> 0-DAY kernel build testing backend              Open Source Technology Center
> http://lists.01.org/mailman/listinfo/kbuild                 Intel Corporation



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [kees:format-security 2/3] arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments
  2014-03-10 17:41 ` [kees:format-security 2/3] arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments Kees Cook
@ 2014-03-11  9:59   ` Matt Fleming
  2014-03-11 20:01     ` Kees Cook
  0 siblings, 1 reply; 3+ messages in thread
From: Matt Fleming @ 2014-03-11  9:59 UTC (permalink / raw)
  To: Kees Cook; +Cc: Paul Mundt, kbuild test robot, LKML, Andrew Morton

On Mon, 10 Mar, at 10:41:57AM, Kees Cook wrote:
> > 4e14dfc7 Matt Fleming 2009-08-07  113  /*
> > 4e14dfc7 Matt Fleming 2009-08-07  114   * Print one address/symbol entries per line.
> > 4e14dfc7 Matt Fleming 2009-08-07  115   */
> > 4e14dfc7 Matt Fleming 2009-08-07  116  static void print_trace_address(void *data, unsigned long addr, int reliable)
> > 4e14dfc7 Matt Fleming 2009-08-07  117  {
> > 4e14dfc7 Matt Fleming 2009-08-07 @118   printk(data);
> 
> This needs to be "printk("%s", data);" so there is no chance of having
> "data" interpreted as a format string itself.

OMG, I suck. Thanks for the report Kees. Have you got a patch for x86?
I think that's where this code came from.

Including Andrew, because I'm not sure who else is going to take this
patch.

---

>From 2284f3a27f68cec665aa982c0a226cf3fbf96ddf Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt.fleming@intel.com>
Date: Tue, 11 Mar 2014 09:50:26 +0000
Subject: [PATCH] sh: Fix format string bug in stack tracer

Kees reported the following error,

   arch/sh/kernel/dumpstack.c: In function 'print_trace_address':
>> arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments [-Werror=format-security]

Use the "%s" format so that it's impossible to interpret 'data' as a
format string.

Reported-by: Kees Cook <keescook@chromium.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 arch/sh/kernel/dumpstack.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sh/kernel/dumpstack.c b/arch/sh/kernel/dumpstack.c
index b959f5592604..8dfe645bcc4b 100644
--- a/arch/sh/kernel/dumpstack.c
+++ b/arch/sh/kernel/dumpstack.c
@@ -115,7 +115,7 @@ static int print_trace_stack(void *data, char *name)
  */
 static void print_trace_address(void *data, unsigned long addr, int reliable)
 {
-	printk(data);
+	printk("%s", (char *)data);
 	printk_address(addr, reliable);
 }
 
-- 
1.8.5.3

-- 
Matt Fleming, Intel Open Source Technology Center

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [kees:format-security 2/3] arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments
  2014-03-11  9:59   ` Matt Fleming
@ 2014-03-11 20:01     ` Kees Cook
  0 siblings, 0 replies; 3+ messages in thread
From: Kees Cook @ 2014-03-11 20:01 UTC (permalink / raw)
  To: Matt Fleming; +Cc: Paul Mundt, kbuild test robot, LKML, Andrew Morton

On Tue, Mar 11, 2014 at 2:59 AM, Matt Fleming <matt@console-pimps.org> wrote:
> On Mon, 10 Mar, at 10:41:57AM, Kees Cook wrote:
>> > 4e14dfc7 Matt Fleming 2009-08-07  113  /*
>> > 4e14dfc7 Matt Fleming 2009-08-07  114   * Print one address/symbol entries per line.
>> > 4e14dfc7 Matt Fleming 2009-08-07  115   */
>> > 4e14dfc7 Matt Fleming 2009-08-07  116  static void print_trace_address(void *data, unsigned long addr, int reliable)
>> > 4e14dfc7 Matt Fleming 2009-08-07  117  {
>> > 4e14dfc7 Matt Fleming 2009-08-07 @118   printk(data);
>>
>> This needs to be "printk("%s", data);" so there is no chance of having
>> "data" interpreted as a format string itself.
>
> OMG, I suck. Thanks for the report Kees. Have you got a patch for x86?
> I think that's where this code came from.

Your patch looks great, thanks!

-Kees

>
> Including Andrew, because I'm not sure who else is going to take this
> patch.
>
> ---
>
> From 2284f3a27f68cec665aa982c0a226cf3fbf96ddf Mon Sep 17 00:00:00 2001
> From: Matt Fleming <matt.fleming@intel.com>
> Date: Tue, 11 Mar 2014 09:50:26 +0000
> Subject: [PATCH] sh: Fix format string bug in stack tracer
>
> Kees reported the following error,
>
>    arch/sh/kernel/dumpstack.c: In function 'print_trace_address':
>>> arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments [-Werror=format-security]
>
> Use the "%s" format so that it's impossible to interpret 'data' as a
> format string.
>
> Reported-by: Kees Cook <keescook@chromium.org>
> Cc: Paul Mundt <lethal@linux-sh.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
> ---
>  arch/sh/kernel/dumpstack.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/sh/kernel/dumpstack.c b/arch/sh/kernel/dumpstack.c
> index b959f5592604..8dfe645bcc4b 100644
> --- a/arch/sh/kernel/dumpstack.c
> +++ b/arch/sh/kernel/dumpstack.c
> @@ -115,7 +115,7 @@ static int print_trace_stack(void *data, char *name)
>   */
>  static void print_trace_address(void *data, unsigned long addr, int reliable)
>  {
> -       printk(data);
> +       printk("%s", (char *)data);
>         printk_address(addr, reliable);
>  }
>
> --
> 1.8.5.3
>
> --
> Matt Fleming, Intel Open Source Technology Center



-- 
Kees Cook
Chrome OS Security

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-03-11 20:01 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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     [not found] <531d3b0e.4MeVQMzUoamEWeW7%fengguang.wu@intel.com>
2014-03-10 17:41 ` [kees:format-security 2/3] arch/sh/kernel/dumpstack.c:118:2: error: format not a string literal and no format arguments Kees Cook
2014-03-11  9:59   ` Matt Fleming
2014-03-11 20:01     ` Kees Cook

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