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authorAmos Waterland <apw@us.ibm.com>2006-09-29 02:00:08 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-29 09:18:12 -0700
commit01d553d0fe9f90a132c5ff494872be8d4126be1e (patch)
tree64d21c1cc1073822c594a57e72aececd5248f1f2
parentf400e198b2ed26ce55b22a1412ded0896e7516ac (diff)
downloadlinaro-lsk-01d553d0fe9f90a132c5ff494872be8d4126be1e.tar.gz
[PATCH] Chardev checking of overlapping ranges
The code in __register_chrdev_region checks that if the driver wishing to register has the same major as an existing driver the new minor range is strictly less than the existing minor range. However, it does not also check that the new minor range is strictly greater than the existing minor range. That is, if driver X has registered with major=x and minor=0-3, __register_chrdev_region will allow driver Y to register with major=x and minor=1-4. Signed-off-by: Amos Waterland <apw@us.ibm.com> Cc: Linas Vepstas <linas@austin.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/char_dev.c28
1 files changed, 23 insertions, 5 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 0009346d827..33b95af89da 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -128,13 +128,31 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
if ((*cp)->major > major ||
- ((*cp)->major == major && (*cp)->baseminor >= baseminor))
+ ((*cp)->major == major &&
+ (((*cp)->baseminor >= baseminor) ||
+ ((*cp)->baseminor + (*cp)->minorct > baseminor))))
break;
- if (*cp && (*cp)->major == major &&
- (*cp)->baseminor < baseminor + minorct) {
- ret = -EBUSY;
- goto out;
+
+ /* Check for overlapping minor ranges. */
+ if (*cp && (*cp)->major == major) {
+ int old_min = (*cp)->baseminor;
+ int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
+ int new_min = baseminor;
+ int new_max = baseminor + minorct - 1;
+
+ /* New driver overlaps from the left. */
+ if (new_max >= old_min && new_max <= old_max) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ /* New driver overlaps from the right. */
+ if (new_min <= old_max && new_min >= old_min) {
+ ret = -EBUSY;
+ goto out;
+ }
}
+
cd->next = *cp;
*cp = cd;
mutex_unlock(&chrdevs_lock);