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    Subject[PATCH AUTOSEL 6.3 20/67] media: dvb-usb: digitv: fix null-ptr-deref in digitv_i2c_xfer()
    Date
    From: Wei Chen <harperchen1110@gmail.com>

    [ Upstream commit 9ded5bd2a49ce3015b7c936743eec0a0e6e11f0c ]

    In digitv_i2c_xfer, msg is controlled by user. When msg[i].buf
    is null and msg[i].len is zero, former checks on msg[i].buf would be
    passed. Malicious data finally reach digitv_i2c_xfer. If accessing
    msg[i].buf[0] without sanity check, null ptr deref would happen. We add
    check on msg[i].len to prevent crash.

    Similar commit:
    commit 0ed554fd769a ("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()")

    Link: https://lore.kernel.org/linux-media/20230313095008.1039689-1-harperchen1110@gmail.com
    Signed-off-by: Wei Chen <harperchen1110@gmail.com>
    Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/media/usb/dvb-usb/digitv.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/drivers/media/usb/dvb-usb/digitv.c b/drivers/media/usb/dvb-usb/digitv.c
    index 2756815a780bc..32134be169148 100644
    --- a/drivers/media/usb/dvb-usb/digitv.c
    +++ b/drivers/media/usb/dvb-usb/digitv.c
    @@ -63,6 +63,10 @@ static int digitv_i2c_xfer(struct i2c_adapter *adap,struct i2c_msg msg[],int num
    warn("more than 2 i2c messages at a time is not handled yet. TODO.");

    for (i = 0; i < num; i++) {
    + if (msg[i].len < 1) {
    + i = -EOPNOTSUPP;
    + break;
    + }
    /* write/read request */
    if (i+1 < num && (msg[i+1].flags & I2C_M_RD)) {
    if (digitv_ctrl_msg(d, USB_READ_COFDM, msg[i].buf[0], NULL, 0,
    --
    2.39.2
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