Remove arbitrary limit in do_insnlist_ioctl() and do_insn_ioctl().

Remove the arbitrary limit on number of samples per instruction.  It
will still be limited by the maximum size of a kmalloc() buffer.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>

diff --git a/comedi/comedi_fops.c b/comedi/comedi_fops.c
index ff09458a704085af71ede960fae06854f0054f23..1adc1db42c205f2208dfe5d55b3d272991eb3c6d 100644 (file)
--- a/comedi/comedi_fops.c
+++ b/comedi/comedi_fops.c
@@ -681,26 +681,18 @@ static int parse_insn(comedi_device * dev, comedi_insn * insn, lsampl_t * data,
  *     writes:
  *             data (for reads)
  */
-/* arbitrary limits */
-#define MAX_SAMPLES 256
 static int do_insnlist_ioctl(comedi_device * dev, void *arg, void *file)
 {
        comedi_insnlist insnlist;
        comedi_insn *insns = NULL;
        lsampl_t *data = NULL;
-       int i = 0;
+       unsigned int max_samples;
+       int i;
        int ret = 0;
 
        if (copy_from_user(&insnlist, arg, sizeof(comedi_insnlist)))
                return -EFAULT;
 
-       data = kmalloc(sizeof(lsampl_t) * MAX_SAMPLES, GFP_KERNEL);
-       if (!data) {
-               DPRINTK("kmalloc failed\n");
-               ret = -ENOMEM;
-               goto error;
-       }
-
        if (insnlist.n_insns <= ULONG_MAX / sizeof(comedi_insn))
                insns = kmalloc(sizeof(comedi_insn) * insnlist.n_insns,
                                GFP_KERNEL);
@@ -717,12 +709,24 @@ static int do_insnlist_ioctl(comedi_device * dev, void *arg, void *file)
                goto error;
        }
 
+       max_samples = 0;
        for (i = 0; i < insnlist.n_insns; i++) {
-               if (insns[i].n > MAX_SAMPLES) {
-                       DPRINTK("number of samples too large\n");
-                       ret = -EINVAL;
+               if (max_samples < insns[i].n)
+                       max_samples = insns[i].n;
+       }
+
+       if (max_samples) {
+               if (max_samples <= ULONG_MAX / sizeof(lsampl_t))
+                       data = kmalloc(sizeof(lsampl_t) * max_samples,
+                                       GFP_KERNEL);
+               if (!data) {
+                       DPRINTK("kmalloc failed\n");
+                       ret = -ENOMEM;
                        goto error;
                }
+       }
+
+       for (i = 0; i < insnlist.n_insns; i++) {
                if (insns[i].insn & INSN_MASK_WRITE) {
                        if (copy_from_user(data, insns[i].data,
                                        insns[i].n * sizeof(lsampl_t))) {
@@ -1001,20 +1005,20 @@ static int do_insn_ioctl(comedi_device * dev, void *arg, void *file)
        lsampl_t *data = NULL;
        int ret = 0;
 
-       data = kmalloc(sizeof(lsampl_t) * MAX_SAMPLES, GFP_KERNEL);
-       if (!data) {
-               ret = -ENOMEM;
-               goto error;
-       }
-
        if (copy_from_user(&insn, arg, sizeof(comedi_insn))) {
                ret = -EFAULT;
                goto error;
        }
 
-       /* This is where the behavior of insn and insnlist deviate. */
-       if (insn.n > MAX_SAMPLES)
-               insn.n = MAX_SAMPLES;
+       if (insn.n) {
+               if (insn.n <= ULONG_MAX / sizeof(lsampl_t))
+                       data = kmalloc(sizeof(lsampl_t) * insn.n, GFP_KERNEL);
+               if (!data) {
+                       ret = -ENOMEM;
+                       goto error;
+               }
+       }
+
        if (insn.insn & INSN_MASK_WRITE) {
                if (copy_from_user(data, insn.data, insn.n * sizeof(lsampl_t))) {
                        ret = -EFAULT;