This is a note to let you know that I've just added the patch titled
staging: comedi: dt3000: Fix signed integer overflow 'divider * base'
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From b4d98bc3fc93ec3a58459948a2c0e0c9b501cd88 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@xxxxxxxxx>
Date: Mon, 12 Aug 2019 12:15:17 +0100
Subject: staging: comedi: dt3000: Fix signed integer overflow 'divider * base'
In `dt3k_ns_to_timer()` the following lines near the end of the function
result in a signed integer overflow:
prescale = 15;
base = timer_base * (1 << prescale);
divider = 65535;
*nanosec = divider * base;
(`divider`, `base` and `prescale` are type `int`, `timer_base` and
`*nanosec` are type `unsigned int`. The value of `timer_base` will be
either 50 or 100.)
The main reason for the overflow is that the calculation for `base` is
completely wrong. It should be:
base = timer_base * (prescale + 1);
which matches an earlier instance of this calculation in the same
function.
Reported-by: David Binderman <dcb314@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Link: https://lore.kernel.org/r/20190812111517.26803-1-abbotti@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/dt3000.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/comedi/drivers/dt3000.c b/drivers/staging/comedi/drivers/dt3000.c
index 2edf3ee91300..4ad176fc14ad 100644
--- a/drivers/staging/comedi/drivers/dt3000.c
+++ b/drivers/staging/comedi/drivers/dt3000.c
@@ -368,7 +368,7 @@ static int dt3k_ns_to_timer(unsigned int timer_base, unsigned int *nanosec,
}
prescale = 15;
- base = timer_base * (1 << prescale);
+ base = timer_base * (prescale + 1);
divider = 65535;
*nanosec = divider * base;
return (prescale << 16) | (divider);
--
2.22.0
