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    Subject[50/71] sound/oss: remove offset from load_patch callbacks
    2.6.33-longterm review patch.  If anyone has any objections, please let us know.

    ------------------

    From: Dan Rosenberg <drosenberg@vsecurity.com>

    commit b769f49463711205d57286e64cf535ed4daf59e9 upstream.

    Was: [PATCH] sound/oss/midi_synth: prevent underflow, use of
    uninitialized value, and signedness issue

    The offset passed to midi_synth_load_patch() can be essentially
    arbitrary. If it's greater than the header length, this will result in
    a copy_from_user(dst, src, negative_val). While this will just return
    -EFAULT on x86, on other architectures this may cause memory corruption.
    Additionally, the length field of the sysex_info structure may not be
    initialized prior to its use. Finally, a signed comparison may result
    in an unintentionally large loop.

    On suggestion by Takashi Iwai, version two removes the offset argument
    from the load_patch callbacks entirely, which also resolves similar
    issues in opl3. Compile tested only.

    v3 adjusts comments and hopefully gets copy offsets right.

    Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    sound/oss/dev_table.h | 2 +-
    sound/oss/midi_synth.c | 30 +++++++++++++-----------------
    sound/oss/midi_synth.h | 2 +-
    sound/oss/opl3.c | 8 ++------
    sound/oss/sequencer.c | 2 +-
    5 files changed, 18 insertions(+), 26 deletions(-)

    --- a/sound/oss/dev_table.h
    +++ b/sound/oss/dev_table.h
    @@ -271,7 +271,7 @@ struct synth_operations
    void (*reset) (int dev);
    void (*hw_control) (int dev, unsigned char *event);
    int (*load_patch) (int dev, int format, const char __user *addr,
    - int offs, int count, int pmgr_flag);
    + int count, int pmgr_flag);
    void (*aftertouch) (int dev, int voice, int pressure);
    void (*controller) (int dev, int voice, int ctrl_num, int value);
    void (*panning) (int dev, int voice, int value);
    --- a/sound/oss/midi_synth.c
    +++ b/sound/oss/midi_synth.c
    @@ -476,7 +476,7 @@ EXPORT_SYMBOL(midi_synth_hw_control);

    int
    midi_synth_load_patch(int dev, int format, const char __user *addr,
    - int offs, int count, int pmgr_flag)
    + int count, int pmgr_flag)
    {
    int orig_dev = synth_devs[dev]->midi_dev;

    @@ -491,33 +491,29 @@ midi_synth_load_patch(int dev, int forma
    if (!prefix_cmd(orig_dev, 0xf0))
    return 0;

    + /* Invalid patch format */
    if (format != SYSEX_PATCH)
    - {
    -/* printk("MIDI Error: Invalid patch format (key) 0x%x\n", format);*/
    return -EINVAL;
    - }
    +
    + /* Patch header too short */
    if (count < hdr_size)
    - {
    -/* printk("MIDI Error: Patch header too short\n");*/
    return -EINVAL;
    - }
    +
    count -= hdr_size;

    /*
    - * Copy the header from user space but ignore the first bytes which have
    - * been transferred already.
    + * Copy the header from user space
    */

    - if(copy_from_user(&((char *) &sysex)[offs], &(addr)[offs], hdr_size - offs))
    + if (copy_from_user(&sysex, addr, hdr_size))
    return -EFAULT;
    -
    - if (count < sysex.len)
    - {
    -/* printk(KERN_WARNING "MIDI Warning: Sysex record too short (%d<%d)\n", count, (int) sysex.len);*/
    +
    + /* Sysex record too short */
    + if ((unsigned)count < (unsigned)sysex.len)
    sysex.len = count;
    - }
    - left = sysex.len;
    - src_offs = 0;
    +
    + left = sysex.len;
    + src_offs = 0;

    for (i = 0; i < left && !signal_pending(current); i++)
    {
    --- a/sound/oss/midi_synth.h
    +++ b/sound/oss/midi_synth.h
    @@ -8,7 +8,7 @@ int midi_synth_open (int dev, int mode);
    void midi_synth_close (int dev);
    void midi_synth_hw_control (int dev, unsigned char *event);
    int midi_synth_load_patch (int dev, int format, const char __user * addr,
    - int offs, int count, int pmgr_flag);
    + int count, int pmgr_flag);
    void midi_synth_panning (int dev, int channel, int pressure);
    void midi_synth_aftertouch (int dev, int channel, int pressure);
    void midi_synth_controller (int dev, int channel, int ctrl_num, int value);
    --- a/sound/oss/opl3.c
    +++ b/sound/oss/opl3.c
    @@ -819,7 +819,7 @@ static void opl3_hw_control(int dev, uns
    }

    static int opl3_load_patch(int dev, int format, const char __user *addr,
    - int offs, int count, int pmgr_flag)
    + int count, int pmgr_flag)
    {
    struct sbi_instrument ins;

    @@ -829,11 +829,7 @@ static int opl3_load_patch(int dev, int
    return -EINVAL;
    }

    - /*
    - * What the fuck is going on here? We leave junk in the beginning
    - * of ins and then check the field pretty close to that beginning?
    - */
    - if(copy_from_user(&((char *) &ins)[offs], addr + offs, sizeof(ins) - offs))
    + if (copy_from_user(&ins, addr, sizeof(ins)))
    return -EFAULT;

    if (ins.channel < 0 || ins.channel >= SBFM_MAXINSTR)
    --- a/sound/oss/sequencer.c
    +++ b/sound/oss/sequencer.c
    @@ -241,7 +241,7 @@ int sequencer_write(int dev, struct file
    return -ENXIO;

    fmt = (*(short *) &event_rec[0]) & 0xffff;
    - err = synth_devs[dev]->load_patch(dev, fmt, buf, p + 4, c, 0);
    + err = synth_devs[dev]->load_patch(dev, fmt, buf + p, c, 0);
    if (err < 0)
    return err;




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