Re: drivers/net/hamradio: divide error in hdlcdrv_ioctl
From: Andrey Konovalov <hidden>
Date: 2017-05-19 00:29:27
Also in:
lkml
On Wed, May 17, 2017 at 10:07 PM, Alan Cox [off-list ref] wrote:
On Tue, 16 May 2017 17:05:32 +0200 Andrey Konovalov [off-list ref] wrote:quoted
Hi, I've got the following error report while fuzzing the kernel with syzkaller. On commit 2ea659a9ef488125eb46da6eb571de5eae5c43f6 (4.12-rc1). A reproducer and .config are attached.This should fix it.
Hi Alan, Someone else has already sent a couple of versions of a similar fix. https://patchwork.ozlabs.org/patch/763832/ Thanks!
quoted hunk ↗ jump to hunk
commit 37b3fa4b617681f00cfa1f76d6d7716cc6d9f79a Author: Alan Cox [off-list ref] Date: Wed May 17 21:04:27 2017 +0100 hdlcdrv: Fix division by zero when bitrate is unset The code attempts to check for out of range calibration. What it forgets to do is check for the 0 bitrate case. As a result the range check itself oopses the kernel. Found by Andrey Konovalov using Syzkaller. Signed-off-by: Alan Cox [off-list ref]diff --git a/drivers/net/hamradio/hdlcdrv.c b/drivers/net/hamradio/hdlcdrv.c index 8c3633c..9f34a48 100644 --- a/drivers/net/hamradio/hdlcdrv.c +++ b/drivers/net/hamradio/hdlcdrv.c@@ -576,7 +576,7 @@ static int hdlcdrv_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) case HDLCDRVCTL_CALIBRATE: if(!capable(CAP_SYS_RAWIO)) return -EPERM; - if (bi.data.calibrate > INT_MAX / s->par.bitrate) + if (!s->par.bitrate || bi.data.calibrate > INT_MAX / s->par.bitrate) return -EINVAL; s->hdlctx.calibrate = bi.data.calibrate * s->par.bitrate / 16; return 0;