[PATCH RESEND 2/2] pps: fix padding issue with PPS_FETCH for ioctl_compat

From: Matt Ranostay
Date: Fri Mar 10 2017 - 18:21:38 EST


Issue is that x86 32-bit aligns to 4-bytes instead of 8-bytes
so this patchset works around the issue and corrects the data
returned in pps_fdata_compat.

Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Acked-by: Rodolfo Giometti <giometti@xxxxxxxxxxxx>
Signed-off-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
---
drivers/pps/pps.c | 110 ++++++++++++++++++++++++++++++++++-------------
include/uapi/linux/pps.h | 19 ++++++++
2 files changed, 98 insertions(+), 31 deletions(-)

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 452ead5a5e52..6eb0db37dd88 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -64,6 +64,43 @@ static int pps_cdev_fasync(int fd, struct file *file, int on)
return fasync_helper(fd, file, on, &pps->async_queue);
}

+static int pps_cdev_pps_fetch(struct pps_device *pps, struct pps_fdata *fdata)
+{
+ unsigned int ev = pps->last_ev;
+ int err = 0;
+
+ /* Manage the timeout */
+ if (fdata->timeout.flags & PPS_TIME_INVALID)
+ err = wait_event_interruptible(pps->queue,
+ ev != pps->last_ev);
+ else {
+ unsigned long ticks;
+
+ dev_dbg(pps->dev, "timeout %lld.%09d\n",
+ (long long) fdata->timeout.sec,
+ fdata->timeout.nsec);
+ ticks = fdata->timeout.sec * HZ;
+ ticks += fdata->timeout.nsec / (NSEC_PER_SEC / HZ);
+
+ if (ticks != 0) {
+ err = wait_event_interruptible_timeout(
+ pps->queue,
+ ev != pps->last_ev,
+ ticks);
+ if (err == 0)
+ return -ETIMEDOUT;
+ }
+ }
+
+ /* Check for pending signals */
+ if (err == -ERESTARTSYS) {
+ dev_dbg(pps->dev, "pending signal caught\n");
+ return -EINTR;
+ }
+
+ return 0;
+}
+
static long pps_cdev_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
@@ -144,7 +181,6 @@ static long pps_cdev_ioctl(struct file *file,

case PPS_FETCH: {
struct pps_fdata fdata;
- unsigned int ev;

dev_dbg(pps->dev, "PPS_FETCH\n");

@@ -152,36 +188,9 @@ static long pps_cdev_ioctl(struct file *file,
if (err)
return -EFAULT;

- ev = pps->last_ev;
-
- /* Manage the timeout */
- if (fdata.timeout.flags & PPS_TIME_INVALID)
- err = wait_event_interruptible(pps->queue,
- ev != pps->last_ev);
- else {
- unsigned long ticks;
-
- dev_dbg(pps->dev, "timeout %lld.%09d\n",
- (long long) fdata.timeout.sec,
- fdata.timeout.nsec);
- ticks = fdata.timeout.sec * HZ;
- ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
-
- if (ticks != 0) {
- err = wait_event_interruptible_timeout(
- pps->queue,
- ev != pps->last_ev,
- ticks);
- if (err == 0)
- return -ETIMEDOUT;
- }
- }
-
- /* Check for pending signals */
- if (err == -ERESTARTSYS) {
- dev_dbg(pps->dev, "pending signal caught\n");
- return -EINTR;
- }
+ err = pps_cdev_pps_fetch(pps, &fdata);
+ if (err)
+ return err;

/* Return the fetched timestamp */
spin_lock_irq(&pps->lock);
@@ -246,8 +255,47 @@ static long pps_cdev_ioctl(struct file *file,
static long pps_cdev_compat_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
+ struct pps_device *pps = file->private_data;
+ void __user *uarg = (void __user *) arg;
+
cmd = _IOC(_IOC_DIR(cmd), _IOC_TYPE(cmd), _IOC_NR(cmd), sizeof(void *));

+ if (cmd == PPS_FETCH) {
+ struct pps_fdata_compat compat;
+ struct pps_fdata fdata;
+ int err;
+
+ dev_dbg(pps->dev, "PPS_FETCH\n");
+
+ err = copy_from_user(&compat, uarg, sizeof(struct pps_fdata_compat));
+ if (err)
+ return -EFAULT;
+
+ memcpy(&fdata.timeout, &compat.timeout,
+ sizeof(struct pps_ktime_compat));
+
+ err = pps_cdev_pps_fetch(pps, &fdata);
+ if (err)
+ return err;
+
+ /* Return the fetched timestamp */
+ spin_lock_irq(&pps->lock);
+
+ compat.info.assert_sequence = pps->assert_sequence;
+ compat.info.clear_sequence = pps->clear_sequence;
+ compat.info.current_mode = pps->current_mode;
+
+ memcpy(&compat.info.assert_tu, &pps->assert_tu,
+ sizeof(struct pps_ktime_compat));
+ memcpy(&compat.info.clear_tu, &pps->clear_tu,
+ sizeof(struct pps_ktime_compat));
+
+ spin_unlock_irq(&pps->lock);
+
+ return copy_to_user(uarg, &compat,
+ sizeof(struct pps_fdata_compat)) ? -EFAULT : 0;
+ }
+
return pps_cdev_ioctl(file, cmd, arg);
}
#else
diff --git a/include/uapi/linux/pps.h b/include/uapi/linux/pps.h
index a9bb1d93451a..c1cb3825a8bc 100644
--- a/include/uapi/linux/pps.h
+++ b/include/uapi/linux/pps.h
@@ -55,6 +55,12 @@ struct pps_ktime {
__s32 nsec;
__u32 flags;
};
+
+struct pps_ktime_compat {
+ __s64 sec;
+ __s32 nsec;
+ __u32 flags;
+} __attribute__((packed, aligned(4)));
#define PPS_TIME_INVALID (1<<0) /* used to specify timeout==NULL */

struct pps_kinfo {
@@ -65,6 +71,14 @@ struct pps_kinfo {
int current_mode; /* current mode bits */
};

+struct pps_kinfo_compat {
+ __u32 assert_sequence; /* seq. num. of assert event */
+ __u32 clear_sequence; /* seq. num. of clear event */
+ struct pps_ktime_compat assert_tu; /* time of assert event */
+ struct pps_ktime_compat clear_tu; /* time of clear event */
+ int current_mode; /* current mode bits */
+};
+
struct pps_kparams {
int api_version; /* API version # */
int mode; /* mode bits */
@@ -114,6 +128,11 @@ struct pps_fdata {
struct pps_ktime timeout;
};

+struct pps_fdata_compat {
+ struct pps_kinfo_compat info;
+ struct pps_ktime_compat timeout;
+};
+
struct pps_bind_args {
int tsformat; /* format of time stamps */
int edge; /* selected event type */
--
2.10.2