[PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[Chen Gang]

When it is kernel symbol, the 'modname' will be NUL, and the 'symname'
contents the valid name.

So for sprintf(), need avoid NUL for '%s'.


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 arch/blackfin/kernel/trace.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/blackfin/kernel/trace.c b/arch/blackfin/kernel/trace.c
index c36efa0..11f98bb 100644
--- a/arch/blackfin/kernel/trace.c
+++ b/arch/blackfin/kernel/trace.c
@@ -51,7 +51,7 @@ void decode_address(char *buf, unsigned long address)
 		if (!modname)
 			modname = delim = "";
 		sprintf(buf, "{ %s%s%s%s + 0x%lx }",
-			delim, modname, delim, symname,
+			delim, modname ? : "kernel", delim, symname,
 			(unsigned long)offset);
 		return;
 	}
-- 
1.7.7.6

[PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[Chen Gang]

When it is kernel symbol, the 'modname' will be NUL, and the 'symname'
contents the valid name.

So for sprintf(), need avoid NUL for '%s'.


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 arch/blackfin/kernel/trace.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/blackfin/kernel/trace.c b/arch/blackfin/kernel/trace.c
index c36efa0..11f98bb 100644
--- a/arch/blackfin/kernel/trace.c
+++ b/arch/blackfin/kernel/trace.c
@@ -51,7 +51,7 @@ void decode_address(char *buf, unsigned long address)
 		if (!modname)
 			modname = delim = "";
 		sprintf(buf, "{ %s%s%s%s + 0x%lx }",
-			delim, modname, delim, symname,
+			delim, modname ? : "kernel", delim, symname,
 			(unsigned long)offset);
 		return;
 	}
-- 
1.7.7.6

[PATCH] arch: blackfin: kernel: memory overflow, 'namebuf' length need be more than 256

[Chen Gang]

The 'name' length in decode_address() may be 255, after call d_path()
successfully.

So for decode_address(), the input 'buf' need be more than 256, or may
memory overflow.

For simply thinking of, use 'namebuf[512]' instead of 'namebuf[150]'
which will pass to decode_address() as input 'buf'.

Also better use macro instead of hard code number when processing
symbols work.


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 arch/blackfin/kernel/trace.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/blackfin/kernel/trace.c b/arch/blackfin/kernel/trace.c
index c36efa0..4fecd3e 100644
--- a/arch/blackfin/kernel/trace.c
+++ b/arch/blackfin/kernel/trace.c
@@ -37,7 +37,7 @@ void decode_address(char *buf, unsigned long address)
 	const char *symname;
 	char *modname;
 	char *delim = ":";
-	char namebuf[128];
+	char namebuf[KSYM_NAME_LEN];
 #endif
 
 	buf += sprintf(buf, "<0x%08lx> ", address);
@@ -845,7 +845,7 @@ void dump_bfin_mem(struct pt_regs *fp)
 
 void show_regs(struct pt_regs *fp)
 {
-	char buf[150];
+	char buf[512];
 	struct irqaction *action;
 	unsigned int i;
 	unsigned long flags = 0;
-- 
1.7.7.6

Re: [PATCH] arch: blackfin: kernel: memory overflow, 'namebuf' length need be more than 256

[Geert Uytterhoeven]

On Wed, May 29, 2013 at 12:07 PM, Chen Gang <gang.chen@asianux.com> wrote:
> The 'name' length in decode_address() may be 255, after call d_path()
> successfully.
>
> So for decode_address(), the input 'buf' need be more than 256, or may
> memory overflow.
>
> For simply thinking of, use 'namebuf[512]' instead of 'namebuf[150]'
> which will pass to decode_address() as input 'buf'.
>
> Also better use macro instead of hard code number when processing
> symbols work.
>
>
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
>  arch/blackfin/kernel/trace.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/blackfin/kernel/trace.c b/arch/blackfin/kernel/trace.c
> index c36efa0..4fecd3e 100644
> --- a/arch/blackfin/kernel/trace.c
> +++ b/arch/blackfin/kernel/trace.c
> @@ -37,7 +37,7 @@ void decode_address(char *buf, unsigned long address)
>         const char *symname;
>         char *modname;
>         char *delim = ":";
> -       char namebuf[128];
> +       char namebuf[KSYM_NAME_LEN];
>  #endif
>
>         buf += sprintf(buf, "<0x%08lx> ", address);
> @@ -845,7 +845,7 @@ void dump_bfin_mem(struct pt_regs *fp)
>
>  void show_regs(struct pt_regs *fp)
>  {
> -       char buf[150];
> +       char buf[512];

This will increase stack usage a lot. And this function calls decode_address(),
which allocates another buffer on the stack.

However, as this is in debug code which is (never?) called concurrently, both
buffers can be made static?

>         struct irqaction *action;
>         unsigned int i;
>         unsigned long flags = 0;

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] arch: blackfin: kernel: memory overflow, 'namebuf' length need be more than 256

[Chen Gang]

On 05/29/2013 07:30 PM, Geert Uytterhoeven wrote:
>>  void show_regs(struct pt_regs *fp)
>> >  {
>> > -       char buf[150];
>> > +       char buf[512];
> This will increase stack usage a lot. And this function calls decode_address(),
> which allocates another buffer on the stack.
> 

Can it have a risk to cause the related stack used up ? (excuse me, I
don't know the system or thread stack size of blackfin).

If so, we really need save some byes (e.g. buf[300] ...), at least. But
I'm not sure whether it still has the risk too.


> However, as this is in debug code which is (never?) called concurrently, both
> buffers can be made static?
> 

trap_c() may call show_regs(), and can multiple traps occur at the same
time ?

It seems it can (but I am not quite sure): for trap_c() only use stack
variables, and "cpu = raw_smp_processor_id()".



Thanks.
-- 
Chen Gang

Asianux Corporation

Re: [PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[Mike Frysinger]

i think you mean NULL instead of NUL

that said, the kernel is smart enough to replace NULL with "(null)",
so i don't see much point in this patch
-mike

On Wed, May 29, 2013 at 5:43 AM, Chen Gang <gang.chen@asianux.com> wrote:
>
> When it is kernel symbol, the 'modname' will be NUL, and the 'symname'
> contents the valid name.
>
> So for sprintf(), need avoid NUL for '%s'.
>
>
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
>  arch/blackfin/kernel/trace.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/blackfin/kernel/trace.c b/arch/blackfin/kernel/trace.c
> index c36efa0..11f98bb 100644
> --- a/arch/blackfin/kernel/trace.c
> +++ b/arch/blackfin/kernel/trace.c
> @@ -51,7 +51,7 @@ void decode_address(char *buf, unsigned long address)
>                 if (!modname)
>                         modname = delim = "";
>                 sprintf(buf, "{ %s%s%s%s + 0x%lx }",
> -                       delim, modname, delim, symname,
> +                       delim, modname ? : "kernel", delim, symname,
>                         (unsigned long)offset);
>                 return;
>         }
> --
> 1.7.7.6
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[Mike Frysinger]

i think you mean NULL instead of NUL

that said, the kernel is smart enough to replace NULL with "(null)",
so i don't see much point in this patch
-mike

On Wed, May 29, 2013 at 5:43 AM, Chen Gang <gang.chen@asianux.com> wrote:
>
> When it is kernel symbol, the 'modname' will be NUL, and the 'symname'
> contents the valid name.
>
> So for sprintf(), need avoid NUL for '%s'.
>
>
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
>  arch/blackfin/kernel/trace.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/blackfin/kernel/trace.c b/arch/blackfin/kernel/trace.c
> index c36efa0..11f98bb 100644
> --- a/arch/blackfin/kernel/trace.c
> +++ b/arch/blackfin/kernel/trace.c
> @@ -51,7 +51,7 @@ void decode_address(char *buf, unsigned long address)
>                 if (!modname)
>                         modname = delim = "";
>                 sprintf(buf, "{ %s%s%s%s + 0x%lx }",
> -                       delim, modname, delim, symname,
> +                       delim, modname ? : "kernel", delim, symname,
>                         (unsigned long)offset);
>                 return;
>         }
> --
> 1.7.7.6
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[Chen Gang]

On 06/16/2013 11:02 AM, Mike Frysinger wrote:
> i think you mean NULL instead of NUL
> 
> that said, the kernel is smart enough to replace NULL with "(null)",
> so i don't see much point in this patch

Oh, really it is, it is my fault (originally, I did not know about it).

Thanks.
-- 
Chen Gang

Asianux Corporation

Re: [PATCH] arch: blackfin: kernel: sprintf(), need avoid NUL for '%s'

[Chen Gang]

On 06/16/2013 11:02 AM, Mike Frysinger wrote:
> i think you mean NULL instead of NUL
> 
> that said, the kernel is smart enough to replace NULL with "(null)",
> so i don't see much point in this patch

Oh, really it is, it is my fault (originally, I did not know about it).

Thanks.
-- 
Chen Gang

Asianux Corporation