From: Zhang Shurong zhang_shurong@foxmail.com

stable inclusion from stable-v4.19.295 commit fa58d9db5cad4bb7bb694b6837e3b96d87554f2b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAPHC5 CVE: CVE-2023-52915

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit 7bf744f2de0a848fb1d717f5831b03db96feae89 ]

In af9035_i2c_master_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 af9035_i2c_master_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()")

Signed-off-by: Zhang Shurong zhang_shurong@foxmail.com Signed-off-by: Hans Verkuil hverkuil-cisco@xs4all.nl Signed-off-by: Sasha Levin sashal@kernel.org [ moved variable declaration to fix build issues in older kernels - gregkh ] Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Ye Bin yebin10@huawei.com --- drivers/media/usb/dvb-usb-v2/af9035.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/media/usb/dvb-usb-v2/af9035.c b/drivers/media/usb/dvb-usb-v2/af9035.c index 1f6c1eefe389..8a83f27875ec 100644 --- a/drivers/media/usb/dvb-usb-v2/af9035.c +++ b/drivers/media/usb/dvb-usb-v2/af9035.c @@ -284,6 +284,7 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap, struct dvb_usb_device *d = i2c_get_adapdata(adap); struct state *state = d_to_priv(d); int ret; + u32 reg;

if (mutex_lock_interruptible(&d->i2c_mutex) < 0) return -EAGAIN; @@ -336,8 +337,10 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap, ret = -EOPNOTSUPP; } else if ((msg[0].addr == state->af9033_i2c_addr[0]) || (msg[0].addr == state->af9033_i2c_addr[1])) { + if (msg[0].len < 3 || msg[1].len < 1) + return -EOPNOTSUPP; /* demod access via firmware interface */ - u32 reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 | + reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 | msg[0].buf[2];

if (msg[0].addr == state->af9033_i2c_addr[1]) @@ -395,17 +398,16 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap, ret = -EOPNOTSUPP; } else if ((msg[0].addr == state->af9033_i2c_addr[0]) || (msg[0].addr == state->af9033_i2c_addr[1])) { + if (msg[0].len < 3) + return -EOPNOTSUPP; /* demod access via firmware interface */ - u32 reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 | + reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 | msg[0].buf[2];

if (msg[0].addr == state->af9033_i2c_addr[1]) reg |= 0x100000;

- ret = (msg[0].len >= 3) ? af9035_wr_regs(d, reg, - &msg[0].buf[3], - msg[0].len - 3) - : -EOPNOTSUPP; + ret = af9035_wr_regs(d, reg, &msg[0].buf[3], msg[0].len - 3); } else { /* I2C write */ u8 buf[MAX_XFER_SIZE];