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sound/oss: remove offset from load_patch callbacks

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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
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2
sound/oss/sequencer.c
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@@ -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;