On Fri May 17 08:58:00 2024 -0700, Nikita Zhandarovich wrote:
> Syzbot reports [1] an uninitialized value issue found by KMSAN in
> dib3000_read_reg().
>
> Local u8 rb[2] is used in i2c_transfer() as a read buffer; in case
> that call fails, the buffer may end up with some undefined values.
>
> Since no elaborate error handling is expected in dib3000_write_reg(),
> simply zero out rb buffer to mitigate the problem.
>
> [1] Syzkaller report
> dvb-usb: bulk message failed: -22 (6/0)
> =====================================================
> BUG: KMSAN: uninit-value in dib3000mb_attach+0x2d8/0x3c0
> drivers/media/dvb-frontends/dib3000mb.c:758
> dib3000mb_attach+0x2d8/0x3c0 drivers/media/dvb-frontends/dib3000mb.c:758
> dibusb_dib3000mb_frontend_attach+0x155/0x2f0
> drivers/media/usb/dvb-usb/dibusb-mb.c:31
> dvb_usb_adapter_frontend_init+0xed/0x9a0
> drivers/media/usb/dvb-usb/dvb-usb-dvb.c:290
> dvb_usb_adapter_init drivers/media/usb/dvb-usb/dvb-usb-init.c:90 [inline]
> dvb_usb_init drivers/media/usb/dvb-usb/dvb-usb-init.c:186 [inline]
> dvb_usb_device_init+0x25a8/0x3760
> drivers/media/usb/dvb-usb/dvb-usb-init.c:310
> dibusb_probe+0x46/0x250 drivers/media/usb/dvb-usb/dibusb-mb.c:110
> ...
> Local variable rb created at:
> dib3000_read_reg+0x86/0x4e0 drivers/media/dvb-frontends/dib3000mb.c:54
> dib3000mb_attach+0x123/0x3c0 drivers/media/dvb-frontends/dib3000mb.c:758
> ...
>
> Fixes: 74340b0a8bc6 ("V4L/DVB (4457): Remove dib3000-common-module")
> Reported-by: syzbot+c88fc0ebe0d5935c7...@syzkaller.appspotmail.com
> Signed-off-by: Nikita Zhandarovich <n.zhandarov...@fintech.ru>
> Link:
> https://lore.kernel.org/r/20240517155800.9881-1-n.zhandarov...@fintech.ru
> Signed-off-by: Mauro Carvalho Chehab <mche...@kernel.org>
Patch committed.
Thanks,
Mauro Carvalho Chehab
drivers/media/dvb-frontends/dib3000mb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/drivers/media/dvb-frontends/dib3000mb.c
b/drivers/media/dvb-frontends/dib3000mb.c
index 822639f11c04..63bc7b74bc8b 100644
--- a/drivers/media/dvb-frontends/dib3000mb.c
+++ b/drivers/media/dvb-frontends/dib3000mb.c
@@ -51,7 +51,7 @@ MODULE_PARM_DESC(debug, "set debugging level
(1=info,2=xfer,4=setfe,8=getfe (|-a
static int dib3000_read_reg(struct dib3000_state *state, u16 reg)
{
u8 wb[] = { ((reg >> 8) | 0x80) & 0xff, reg & 0xff };
- u8 rb[2];
+ u8 rb[2] = {};
struct i2c_msg msg[] = {
{ .addr = state->config.demod_address, .flags = 0, .buf
= wb, .len = 2 },
{ .addr = state->config.demod_address, .flags = I2C_M_RD, .buf
= rb, .len = 2 },
