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sound/oss: remove offset from load_patch callbacks 

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>
This commit is contained in:
Dan Rosenberg 2011-03-23 10:53:41 -04:00 committed by Takashi Iwai
parent ce24f58a11
commit b769f49463
5 changed files with 18 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sound/oss/dev_table.h
View File

@ -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);

24
sound/oss/midi_synth.c
View File

@ -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;
@ -491,31 +491,27 @@ midi_synth_load_patch(int dev, int format, const char __user *addr,
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;

2
sound/oss/midi_synth.h
View File

@ -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);

8
sound/oss/opl3.c
View File

@ -820,7 +820,7 @@ static void opl3_hw_control(int dev, unsigned char *event)
}
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;
@ -830,11 +830,7 @@ static int opl3_load_patch(int dev, int format, const char __user *addr,
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)

2
sound/oss/sequencer.c
View File

@ -241,7 +241,7 @@ int sequencer_write(int dev, struct file *file, const char __user *buf, int coun
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;