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Subject[PATCH 06/10] comedi: get rid of compat_alloc_user_space() mess in COMEDI_INSNLIST compat
Date
From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
drivers/staging/comedi/comedi_fops.c | 138 ++++++++++++-----------------------
1 file changed, 48 insertions(+), 90 deletions(-)

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index ae0067ab5ead..d80a416e70b2 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1520,34 +1520,19 @@ static int parse_insn(struct comedi_device *dev, struct comedi_insn *insn,
#define MIN_SAMPLES 16
#define MAX_SAMPLES 65536
static int do_insnlist_ioctl(struct comedi_device *dev,
- struct comedi_insnlist __user *arg, void *file)
+ struct comedi_insn *insns,
+ unsigned int n_insns,
+ void *file)
{
- struct comedi_insnlist insnlist;
- struct comedi_insn *insns = NULL;
unsigned int *data = NULL;
unsigned int max_n_data_required = MIN_SAMPLES;
int i = 0;
int ret = 0;

lockdep_assert_held(&dev->mutex);
- if (copy_from_user(&insnlist, arg, sizeof(insnlist)))
- return -EFAULT;
-
- insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
- if (!insns) {
- ret = -ENOMEM;
- goto error;
- }
-
- if (copy_from_user(insns, insnlist.insns,
- sizeof(*insns) * insnlist.n_insns)) {
- dev_dbg(dev->class_dev, "copy_from_user failed\n");
- ret = -EFAULT;
- goto error;
- }

/* Determine maximum memory needed for all instructions. */
- for (i = 0; i < insnlist.n_insns; ++i) {
+ for (i = 0; i < n_insns; ++i) {
if (insns[i].n > MAX_SAMPLES) {
dev_dbg(dev->class_dev,
"number of samples too large\n");
@@ -1565,7 +1550,7 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
goto error;
}

- for (i = 0; i < insnlist.n_insns; ++i) {
+ for (i = 0; i < n_insns; ++i) {
if (insns[i].insn & INSN_MASK_WRITE) {
if (copy_from_user(data, insns[i].data,
insns[i].n * sizeof(unsigned int))) {
@@ -1592,7 +1577,6 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
}

error:
- kfree(insns);
kfree(data);

if (ret < 0)
@@ -2236,11 +2220,30 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
rc = do_cmdtest_ioctl(dev, (struct comedi_cmd __user *)arg,
file);
break;
- case COMEDI_INSNLIST:
- rc = do_insnlist_ioctl(dev,
- (struct comedi_insnlist __user *)arg,
- file);
+ case COMEDI_INSNLIST: {
+ struct comedi_insnlist insnlist;
+ struct comedi_insn *insns = NULL;
+
+ if (copy_from_user(&insnlist, (void __user *)arg,
+ sizeof(insnlist))) {
+ rc = -EFAULT;
+ break;
+ }
+ insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
+ if (!insns) {
+ rc = -ENOMEM;
+ break;
+ }
+ if (copy_from_user(insns, insnlist.insns,
+ sizeof(*insns) * insnlist.n_insns)) {
+ rc = -EFAULT;
+ kfree(insns);
+ break;
+ }
+ rc = do_insnlist_ioctl(dev, insns, insnlist.n_insns, file);
+ kfree(insns);
break;
+ }
case COMEDI_INSN: {
struct comedi_insn insn;
if (copy_from_user(&insn, (void __user *)arg, sizeof(insn)))
@@ -3094,83 +3097,38 @@ static int get_compat_insn(struct comedi_insn *insn,
return 0;
}

-/* Copy 32-bit insn structure to native insn structure. */
-static int __get_compat_insn(struct comedi_insn __user *insn,
- struct comedi32_insn_struct __user *insn32)
-{
- int err;
- union {
- unsigned int uint;
- compat_uptr_t uptr;
- } temp;
-
- /* Copy insn structure. Ignore the unused members. */
- err = 0;
- if (!access_ok(insn32, sizeof(*insn32)) ||
- !access_ok(insn, sizeof(*insn)))
- return -EFAULT;
-
- err |= __get_user(temp.uint, &insn32->insn);
- err |= __put_user(temp.uint, &insn->insn);
- err |= __get_user(temp.uint, &insn32->n);
- err |= __put_user(temp.uint, &insn->n);
- err |= __get_user(temp.uptr, &insn32->data);
- err |= __put_user(compat_ptr(temp.uptr), &insn->data);
- err |= __get_user(temp.uint, &insn32->subdev);
- err |= __put_user(temp.uint, &insn->subdev);
- err |= __get_user(temp.uint, &insn32->chanspec);
- err |= __put_user(temp.uint, &insn->chanspec);
- return err ? -EFAULT : 0;
-}
-
/* Handle 32-bit COMEDI_INSNLIST ioctl. */
static int compat_insnlist(struct file *file, unsigned long arg)
{
- struct combined_insnlist {
- struct comedi_insnlist insnlist;
- struct comedi_insn insn[1];
- } __user *s;
- struct comedi32_insnlist_struct __user *insnlist32;
+ struct comedi_file *cfp = file->private_data;
+ struct comedi_device *dev = cfp->dev;
+ struct comedi32_insnlist_struct insnlist32;
struct comedi32_insn_struct __user *insn32;
- compat_uptr_t uptr;
- unsigned int n_insns, n;
- int err, rc;
-
- insnlist32 = compat_ptr(arg);
-
- /* Get 32-bit insnlist structure. */
- if (!access_ok(insnlist32, sizeof(*insnlist32)))
- return -EFAULT;
-
- err = 0;
- err |= __get_user(n_insns, &insnlist32->n_insns);
- err |= __get_user(uptr, &insnlist32->insns);
- insn32 = compat_ptr(uptr);
- if (err)
- return -EFAULT;
-
- /* Allocate user memory to copy insnlist and insns into. */
- s = compat_alloc_user_space(offsetof(struct combined_insnlist,
- insn[n_insns]));
+ struct comedi_insn *insns;
+ unsigned int n;
+ int rc;

- /* Set native insnlist structure. */
- if (!access_ok(&s->insnlist, sizeof(s->insnlist)))
+ if (copy_from_user(&insnlist32, compat_ptr(arg), sizeof(insnlist32)))
return -EFAULT;

- err |= __put_user(n_insns, &s->insnlist.n_insns);
- err |= __put_user(&s->insn[0], &s->insnlist.insns);
- if (err)
- return -EFAULT;
+ insns = kcalloc(insnlist32.n_insns, sizeof(*insns), GFP_KERNEL);
+ if (!insns)
+ return -ENOMEM;

/* Copy insn structures. */
- for (n = 0; n < n_insns; n++) {
- rc = __get_compat_insn(&s->insn[n], &insn32[n]);
- if (rc)
+ insn32 = compat_ptr(insnlist32.insns);
+ for (n = 0; n < insnlist32.n_insns; n++) {
+ rc = get_compat_insn(insns + n, insn32 + n);
+ if (rc) {
+ kfree(insns);
return rc;
+ }
}

- return comedi_unlocked_ioctl(file, COMEDI_INSNLIST,
- (unsigned long)&s->insnlist);
+ mutex_lock(&dev->mutex);
+ rc = do_insnlist_ioctl(dev, insns, insnlist32.n_insns, file);
+ mutex_unlock(&dev->mutex);
+ return rc;
}

/* Handle 32-bit COMEDI_INSN ioctl. */
--
2.11.0
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