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ALSA: rawmidi: fix oops (use after free) when unloading a driver module 

When a driver module is unloaded and the last still open file is a raw
MIDI device, the card and its devices will be actually freed in the
snd_card_file_remove() call when that file is closed.  Afterwards, rmidi
and rmidi->card point into freed memory, so the module pointer is likely
to be garbage.
(This was introduced by commit 9a1b64caac82aa02cb74587ffc798e6f42c6170a.)

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-by: Krzysztof Foltman <wdev@foltman.com>
Cc: 2.6.30-2.6.35 <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2010-10-15 12:06:18 +02:00 committed by Takashi Iwai
parent cd07202cc8
commit aa73aec6c3
1 changed files with 3 additions and 1 deletions
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4
sound/core/rawmidi.c
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@ -535,13 +535,15 @@ static int snd_rawmidi_release(struct inode *inode, struct file *file)
{
struct snd_rawmidi_file *rfile;
struct snd_rawmidi *rmidi;
struct module *module;
rfile = file->private_data;
rmidi = rfile->rmidi;
rawmidi_release_priv(rfile);
kfree(rfile);
module = rmidi->card->module;
snd_card_file_remove(rmidi->card, file);
module_put(rmidi->card->module);
module_put(module);
return 0;
}