6.1-stable review patch. If anyone has any objections, please let me know.
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From: Jiaming Zhang r772577952@gmail.com
[ Upstream commit 28412b489b088fb88dff488305fd4e56bd47f6e4 ]
In try_to_register_card(), the return value of usb_ifnum_to_if() is passed directly to usb_interface_claimed() without a NULL check, which will lead to a NULL pointer dereference when creating an invalid USB audio device. Fix this by adding a check to ensure the interface pointer is valid before passing it to usb_interface_claimed().
Fixes: 39efc9c8a973 ("ALSA: usb-audio: Fix last interface check for registration") Closes: https://lore.kernel.org/all/CANypQFYtQxHL5ghREs-BujZG413RPJGnO5TH=xjFBKpPts3... Signed-off-by: Jiaming Zhang r772577952@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/usb/card.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/sound/usb/card.c b/sound/usb/card.c index 5f539a1baef3d..d7fe1c22a48bb 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -753,10 +753,16 @@ get_alias_quirk(struct usb_device *dev, unsigned int id) */ static int try_to_register_card(struct snd_usb_audio *chip, int ifnum) { + struct usb_interface *iface; + if (check_delayed_register_option(chip) == ifnum || - chip->last_iface == ifnum || - usb_interface_claimed(usb_ifnum_to_if(chip->dev, chip->last_iface))) + chip->last_iface == ifnum) + return snd_card_register(chip->card); + + iface = usb_ifnum_to_if(chip->dev, chip->last_iface); + if (iface && usb_interface_claimed(iface)) return snd_card_register(chip->card); + return 0; }