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

[Geert Uytterhoeven]

On Wed, May 29, 2013 at 12:07 PM, Chen Gang <gang.chen@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxxx

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/