From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 30 Nov 2011 18:34:16 +0000 (-0500)
Subject: lttng lib: ring buffer move null pointer check to open
X-Git-Tag: v3.3-rc1~152^2~101^2~112
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eeb34e2113576aea782094d1e30f22b445355fe8;p=pandora-kernel.git

lttng lib: ring buffer move null pointer check to open

* Dan Carpenter <dan.carpenter@oracle.com> wrote:
> The patch c844b2f5cfea: "lttng lib: ring buffer" from Nov 28, 2011,
> leads to the following Smatch complaint:
>
> drivers/staging/lttng/lib/ringbuffer/ring_buffer_mmap.c +86
> +lib_ring_buffer_mmap_buf()
>          warn: variable dereferenced before check 'buf' (see line 79)
>
> drivers/staging/lttng/lib/ringbuffer/ring_buffer_mmap.c
>     78          unsigned long length = vma->vm_end - vma->vm_start;
>     79          struct channel *chan = buf->backend.chan;
>                                        ^^^^^^^^^^^^^^^^^
> Dereference.
>
>     80          const struct lib_ring_buffer_config *config = chan->backend.config;
>     81          unsigned long mmap_buf_len;
>     82
>     83          if (config->output != RING_BUFFER_MMAP)
>     84                  return -EINVAL;
>     85
>     86          if (!buf)
>                     ^^^^
> Check.
>
>     87                  return -EBADF;
>     88

Let's move the NULL buf check to the file "open", where it belongs. The
"open" file operation is the actual interface between lib ring buffer
and the modules using it.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

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