[alsa-devel] [PATCH] SOUND: usb/endpoint, fix dangling pointer use

Jiri Slaby jslaby at suse.cz
Mon Jun 21 17:03:21 CEST 2010

Stanse found that in snd_usb_parse_audio_endpoints, there is a
dangling pointer dereference. When snd_usb_parse_audio_format fails,
fp is freed, and continue invoked. On the next loop, there is
"fp && fp->altsetting == 1 && fp->channels == 1" test, but fp is set
from the last iteration (but is bogus) and thus ilegally dereferenced.

Set fp to NULL before "continue".

Signed-off-by: Jiri Slaby <jslaby at suse.cz>
Cc: Daniel Mack <daniel at caiaq.de>
Cc: Clemens Ladisch <clemens at ladisch.de>
Cc: Takashi Iwai <tiwai at suse.de>
 sound/usb/endpoint.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 9593b91..6f6596c 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -427,6 +427,7 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
 		if (snd_usb_parse_audio_format(chip, fp, format, fmt, stream, alts) < 0) {
+			fp = NULL;

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