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    Subject[PATCH 1/3] drivers/staging/cx25821: Use kasprintf
    Date
    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@diku.dk>

    ---
    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;
    }

    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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