Changes do_insn*_ioctl functions to allow for data lengths for each
comedi_insn of up to 2^16. This patch also changes these functions to only
allocate as much memory as is necessary for each comedi_insn, rather than
allocating a fixed-sized scratch space.
In testing some user-space code for the new INSN_DEVICE_CONFIG_GET_ROUTES
facility with some newer hardware, I discovered that do_insn_ioctl and
do_insnlist_ioctl limited the amount of data that can be passed into the
kernel for insn's to a length of 256. For some newer hardware, the number
of routes can be greater than 1000. Working around the old limits (256)
would complicate the user-space/kernel interaction.
The new upper limit is reasonable with current memory available and does
not otherwise impact the memory footprint for any current or otherwise
typical configuration.
Signed-off-by: Spencer E. Olson <olso...@umich.edu>
---
drivers/staging/comedi/comedi_fops.c | 37 +++++++++++++++++-----------
1 file changed, 22 insertions(+), 15 deletions(-)
diff --git a/drivers/staging/comedi/comedi_fops.c
b/drivers/staging/comedi/comedi_fops.c
index c1c6b2b4ab91..a163ec2df872 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1500,7 +1500,7 @@ static int parse_insn(struct comedi_device *dev, struct
comedi_insn *insn,
* data (for reads) to insns[].data pointers
*/
/* arbitrary limits */
-#define MAX_SAMPLES 256
+#define MAX_SAMPLES 65536
static int do_insnlist_ioctl(struct comedi_device *dev,
struct comedi_insnlist __user *arg, void *file)
{
@@ -1513,12 +1513,6 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
if (copy_from_user(&insnlist, arg, sizeof(insnlist)))
return -EFAULT;
- data = kmalloc_array(MAX_SAMPLES, sizeof(unsigned int), GFP_KERNEL);
- if (!data) {
- ret = -ENOMEM;
- goto error;
- }
-
insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
if (!insns) {
ret = -ENOMEM;
@@ -1539,6 +1533,14 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
ret = -EINVAL;
goto error;
}
+
+ data = kmalloc_array(insns[i].n, sizeof(unsigned int),
+ GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
if (insns[i].insn & INSN_MASK_WRITE) {
if (copy_from_user(data, insns[i].data,
insns[i].n * sizeof(unsigned int))) {
@@ -1560,6 +1562,11 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
goto error;
}
}
+
+ /* free up the single-instruction data memory */
+ kfree(data);
+ data = NULL;
+
if (need_resched())
schedule();
}
@@ -1594,20 +1601,20 @@ static int do_insn_ioctl(struct comedi_device *dev,
unsigned int *data = NULL;
int ret = 0;
- data = kmalloc_array(MAX_SAMPLES, sizeof(unsigned int), GFP_KERNEL);
- if (!data) {
- ret = -ENOMEM;
- goto error;
- }
-
if (copy_from_user(&insn, arg, sizeof(insn))) {
- ret = -EFAULT;
- goto error;
+ return -EFAULT;
}
/* This is where the behavior of insn and insnlist deviate. */
if (insn.n > MAX_SAMPLES)
insn.n = MAX_SAMPLES;
+
+ data = kmalloc_array(insn.n, sizeof(unsigned int), GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
if (insn.insn & INSN_MASK_WRITE) {
if (copy_from_user(data,
insn.data,
--
2.17.1
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