[PATCH AUTOSEL 4.9 01/23] media: af9035: prevent buffer overflow on write

Sasha Levin
2018-10-08T15:27:09Z

From: Jozef Balga <jozef.balga@gmail.com>

[ Upstream commit 312f73b648626a0526a3aceebb0a3192aaba05ce ]

When less than 3 bytes are written to the device, memcpy is called with
negative array size which leads to buffer overflow and kernel panic. This
patch adds a condition and returns -EOPNOTSUPP instead.
Fixes bugzilla issue 64871

[mchehab+samsung@kernel.org: fix a merge conflict and changed the
condition to match the patch's comment, e. g. len == 3 could
also be valid]
Signed-off-by: Jozef Balga <jozef.balga@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/media/usb/dvb-usb-v2/af9035.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/dvb-usb-v2/af9035.c b/drivers/media/usb/dvb-usb-v2/af9035.c
index 8961dd732522..64be30d53847 100644
--- a/drivers/media/usb/dvb-usb-v2/af9035.c
+++ b/drivers/media/usb/dvb-usb-v2/af9035.c
@@ -406,8 +406,10 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
msg[0].addr == (state->af9033_i2c_addr[1] >> 1))
reg |= 0x100000;

- ret = af9035_wr_regs(d, reg, &msg[0].buf[3],
- msg[0].len - 3);
+ ret = (msg[0].len >= 3) ? af9035_wr_regs(d, reg,
+ &msg[0].buf[3],
+ msg[0].len - 3)
+ : -EOPNOTSUPP;
} else {
/* I2C write */
u8 buf[MAX_XFER_SIZE];
--
2.17.1