I4L: fix isdn_ioctl memory overrun vulnerability

Fix possible memory overrun issue in the isdn ioctl code.

Found by ADLAB <adlab@venustech.com.cn>

Signed-off-by: Karsten Keil <kkeil@suse.de>
Cc: ADLAB <adlab@venustech.com.cn>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index c6df2925ebd0..d6952959d72a 100644
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -1515,6 +1515,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
                                         if (copy_from_user(&iocts, argp,
                                              sizeof(isdn_ioctl_struct)))
                                                 return -EFAULT;
+                                        iocts.drvid[sizeof(iocts.drvid)-1] = 0;
                                         if (strlen(iocts.drvid)) {
                                                 if ((p = strchr(iocts.drvid, ',')))
                                                         *p = 0;
@@ -1599,6 +1600,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
                                         if (copy_from_user(&iocts, argp,
                                              sizeof(isdn_ioctl_struct)))
                                                 return -EFAULT;
+                                        iocts.drvid[sizeof(iocts.drvid)-1] = 0;
                                         if (strlen(iocts.drvid)) {
                                                 drvidx = -1;
                                                 for (i = 0; i < ISDN_MAX_DRIVERS; i++)
@@ -1643,7 +1645,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
                                         } else {
                                                 p = (char __user *) iocts.arg;
                                                 for (i = 0; i < 10; i++) {
-                                                        sprintf(bname, "%s%s",
+                                                        snprintf(bname, sizeof(bname), "%s%s",
                                                                 strlen(dev->drv[drvidx]->msn2eaz[i]) ?
                                                                 dev->drv[drvidx]->msn2eaz[i] : "_",
                                                                 (i < 9) ? "," : "\0");
@@ -1673,6 +1675,7 @@ isdn_ioctl(struct inode *inode, struct file *file, uint cmd, ulong arg)
                                         char *p;
                                         if (copy_from_user(&iocts, argp, sizeof(isdn_ioctl_struct)))
                                                 return -EFAULT;
+                                        iocts.drvid[sizeof(iocts.drvid)-1] = 0;
                                         if (strlen(iocts.drvid)) {
                                                 if ((p = strchr(iocts.drvid, ',')))
                                                         *p = 0;