Re: [PATCH 1/3] drivers/staging/cx25821: Use kasprintf

From: walter harms
Date: Mon Oct 18 2010 - 03:15:38 EST



Julia Lawall schrieb:
> Rewrite the initialization of a dev field. In the original code, in each
> case there was a kmalloc followed by a memcpy, as illustrated by the
> semantic patch below. In the case that the provided string was the empty
> string, the allocated memory was then overwritten with a constant string,
> causing a memory leak. Finally, there was no provision for returning
> -ENOMEM in case of failure of the memory allocation. Indeed, the return
> value in an error case was err, a variable that was never initialized to
> anything other than 0.
>
> The following patch rewrites the above code to first select a string based
> on various conditions, and then to copy it into a newly allocated memory
> region, using kasprintf. This decreases subtantially the code size
> and removes the memory leak. The instruction for getting the length of the
> string and the associated variable declaration are also deleted.
>
> The patch also drops err, changes the return value to retval, which in each
> file was already initialized elsewhere to an error code, and initializes
> retval to -ENOMEM when kasprintf fails.
>
> The semantic patch that motivated this transformation is:
> (http://coccinelle.lip6.fr/)
>
> // <smpl>
> @@
> expression a,flag,len;
> expression arg,e1,e2;
> statement S;
> @@
>
> len = strlen(arg)
> ... when != len = e1
> when != arg = e2
> a =
> - \(kmalloc\|kzalloc\)(len+1,flag)
> + kasprintf(flag,"%s",arg)
> <... when != a
> if (a == NULL || ...) S
> ...>
> - memcpy(a,arg,len+1);
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@xxxxxxx>
>
> ---
> This patch makes quite a lot of changes and is only compile tested.
>
> drivers/staging/cx25821/cx25821-audio-upstream.c | 36 +++---------
> drivers/staging/cx25821/cx25821-video-upstream-ch2.c | 57 +++++++------------
> drivers/staging/cx25821/cx25821-video-upstream.c | 56 +++++++-----------
> 3 files changed, 56 insertions(+), 93 deletions(-)
>
> diff --git a/drivers/staging/cx25821/cx25821-audio-upstream.c b/drivers/staging/cx25821/cx25821-audio-upstream.c
> index 27087db..a8f6343 100644
> --- a/drivers/staging/cx25821/cx25821-audio-upstream.c
> +++ b/drivers/staging/cx25821/cx25821-audio-upstream.c
> @@ -723,8 +723,7 @@ int cx25821_audio_upstream_init(struct cx25821_dev *dev, int channel_select)
> {
> struct sram_channel *sram_ch;
> int retval = 0;
> - int err = 0;
> - int str_length = 0;
> + char *filename;
>
> if (dev->_audio_is_running) {
> printk(KERN_WARNING "Audio Channel is still running so return!\n");
> @@ -752,28 +751,15 @@ int cx25821_audio_upstream_init(struct cx25821_dev *dev, int channel_select)
> dev->_audio_lines_count = LINES_PER_AUDIO_BUFFER;
> _line_size = AUDIO_LINE_SIZE;
>
> - if (dev->input_audiofilename) {
> - str_length = strlen(dev->input_audiofilename);
> - dev->_audiofilename = kmalloc(str_length + 1, GFP_KERNEL);
> -
> - if (!dev->_audiofilename)
> - goto error;
> -
> - memcpy(dev->_audiofilename, dev->input_audiofilename,
> - str_length + 1);
> -
> - /* Default if filename is empty string */
> - if (strcmp(dev->input_audiofilename, "") == 0)
> - dev->_audiofilename = "/root/audioGOOD.wav";
> -
> - } else {
> - str_length = strlen(_defaultAudioName);
> - dev->_audiofilename = kmalloc(str_length + 1, GFP_KERNEL);
> -
> - if (!dev->_audiofilename)
> - goto error;
> -
> - memcpy(dev->_audiofilename, _defaultAudioName, str_length + 1);
> + if (dev->input_audiofilename &&
> + strcmp(dev->input_audiofilename, "") != 0)
> + filename = dev->input_audiofilename;
> + else
> + filename = _defaultAudioName;
> + dev->_audiofilename = kasprintf(GFP_KERNEL, "%s", filename);
> + if (!dev->_audiofilename) {
> + retval = -ENOMEM;
> + goto error;
> }
>

Is filename needed here at all ?
The if statement looks strange this looks more familar to me:
if (!dev->input_audiofilename || *dev->input_audiofilename==0)
filename = _defaultAudioName;
else
filename = dev->input_audiofilename;

re
wh


> retval =
> @@ -802,5 +788,5 @@ int cx25821_audio_upstream_init(struct cx25821_dev *dev, int channel_select)
> error:
> cx25821_dev_unregister(dev);
>
> - return err;
> + return retval;
> }
> diff --git a/drivers/staging/cx25821/cx25821-video-upstream-ch2.c b/drivers/staging/cx25821/cx25821-video-upstream-ch2.c
> index d12dbb5..531e0c4 100644
> --- a/drivers/staging/cx25821/cx25821-video-upstream-ch2.c
> +++ b/drivers/staging/cx25821/cx25821-video-upstream-ch2.c
> @@ -747,10 +747,9 @@ int cx25821_vidupstream_init_ch2(struct cx25821_dev *dev, int channel_select,
> struct sram_channel *sram_ch;
> u32 tmp;
> int retval = 0;
> - int err = 0;
> int data_frame_size = 0;
> int risc_buffer_size = 0;
> - int str_length = 0;
> + char *filename;
>
> if (dev->_is_running_ch2) {
> printk("Video Channel is still running so return!\n");
> @@ -789,38 +788,26 @@ int cx25821_vidupstream_init_ch2(struct cx25821_dev *dev, int channel_select,
> dev->_isNTSC_ch2 ? NTSC_RISC_BUF_SIZE : PAL_RISC_BUF_SIZE;
>
> if (dev->input_filename_ch2) {
> - str_length = strlen(dev->input_filename_ch2);
> - dev->_filename_ch2 = kmalloc(str_length + 1, GFP_KERNEL);
> -
> - if (!dev->_filename_ch2)
> - goto error;
> -
> - memcpy(dev->_filename_ch2, dev->input_filename_ch2,
> - str_length + 1);
> - } else {
> - str_length = strlen(dev->_defaultname_ch2);
> - dev->_filename_ch2 = kmalloc(str_length + 1, GFP_KERNEL);
> -
> - if (!dev->_filename_ch2)
> - goto error;
> -
> - memcpy(dev->_filename_ch2, dev->_defaultname_ch2,
> - str_length + 1);
> - }
> -
> - /* Default if filename is empty string */
> - if (strcmp(dev->input_filename_ch2, "") == 0) {
> - if (dev->_isNTSC_ch2) {
> - dev->_filename_ch2 =
> - (dev->_pixel_format_ch2 ==
> - PIXEL_FRMT_411) ? "/root/vid411.yuv" :
> - "/root/vidtest.yuv";
> - } else {
> - dev->_filename_ch2 =
> - (dev->_pixel_format_ch2 ==
> - PIXEL_FRMT_411) ? "/root/pal411.yuv" :
> - "/root/pal422.yuv";
> - }
> + /* Default if filename is empty string */
> + if (strcmp(dev->input_filename_ch2, "") == 0) {
> + if (dev->_isNTSC_ch2)
> + filename =
> + (dev->_pixel_format_ch2 ==
> + PIXEL_FRMT_411) ? "/root/vid411.yuv" :
> + "/root/vidtest.yuv";
> + else
> + filename =
> + (dev->_pixel_format_ch2 ==
> + PIXEL_FRMT_411) ? "/root/pal411.yuv" :
> + "/root/pal422.yuv";
> + } else
> + filename = dev->input_filename_ch2;
> + } else
> + filename = dev->_defaultname_ch2;
> + dev->_filename_ch2 = kasprintf(GFP_KERNEL, "%s", filename);
> + if (!dev->_filename_ch2) {
> + retval = -ENOMEM;
> + goto error;
> }
>
> retval =
> @@ -851,5 +838,5 @@ int cx25821_vidupstream_init_ch2(struct cx25821_dev *dev, int channel_select,
> error:
> cx25821_dev_unregister(dev);
>
> - return err;
> + return retval;
> }
> diff --git a/drivers/staging/cx25821/cx25821-video-upstream.c b/drivers/staging/cx25821/cx25821-video-upstream.c
> index 756a820..040f795 100644
> --- a/drivers/staging/cx25821/cx25821-video-upstream.c
> +++ b/drivers/staging/cx25821/cx25821-video-upstream.c
> @@ -800,10 +800,9 @@ int cx25821_vidupstream_init_ch1(struct cx25821_dev *dev, int channel_select,
> struct sram_channel *sram_ch;
> u32 tmp;
> int retval = 0;
> - int err = 0;
> int data_frame_size = 0;
> int risc_buffer_size = 0;
> - int str_length = 0;
> + char *filename;
>
> if (dev->_is_running) {
> printk(KERN_INFO "Video Channel is still running so return!\n");
> @@ -841,36 +840,27 @@ int cx25821_vidupstream_init_ch1(struct cx25821_dev *dev, int channel_select,
> dev->_isNTSC ? NTSC_RISC_BUF_SIZE : PAL_RISC_BUF_SIZE;
>
> if (dev->input_filename) {
> - str_length = strlen(dev->input_filename);
> - dev->_filename = kmalloc(str_length + 1, GFP_KERNEL);
> -
> - if (!dev->_filename)
> - goto error;
> -
> - memcpy(dev->_filename, dev->input_filename, str_length + 1);
> - } else {
> - str_length = strlen(dev->_defaultname);
> - dev->_filename = kmalloc(str_length + 1, GFP_KERNEL);
> -
> - if (!dev->_filename)
> - goto error;
> -
> - memcpy(dev->_filename, dev->_defaultname, str_length + 1);
> - }
> -
> - /* Default if filename is empty string */
> - if (strcmp(dev->input_filename, "") == 0) {
> - if (dev->_isNTSC) {
> - dev->_filename =
> - (dev->_pixel_format ==
> - PIXEL_FRMT_411) ? "/root/vid411.yuv" :
> - "/root/vidtest.yuv";
> - } else {
> - dev->_filename =
> - (dev->_pixel_format ==
> - PIXEL_FRMT_411) ? "/root/pal411.yuv" :
> - "/root/pal422.yuv";
> - }
> + /* Default if filename is empty string */
> + if (strcmp(dev->input_filename, "") == 0) {
> + if (dev->_isNTSC)
> + filename =
> + (dev->_pixel_format ==
> + PIXEL_FRMT_411) ? "/root/vid411.yuv" :
> + "/root/vidtest.yuv";
> + else
> + filename =
> + (dev->_pixel_format ==
> + PIXEL_FRMT_411) ? "/root/pal411.yuv" :
> + "/root/pal422.yuv";
> + } else
> + filename = dev->input_filename;
> + } else
> + filename = dev->_defaultname;
> +
> + dev->_filename = kasprintf(GFP_KERNEL, "%s", filename);
> + if (!dev->_filename) {
> + retval = -ENOMEM;
> + goto error;
> }
>
> dev->_is_running = 0;
> @@ -908,5 +898,5 @@ int cx25821_vidupstream_init_ch1(struct cx25821_dev *dev, int channel_select,
> error:
> cx25821_dev_unregister(dev);
>
> - return err;
> + return retval;
> }
>
> --
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