The patch titled
Fix bounds check bug in __register_chrdev_region
has been added to the -mm tree. Its filename is
fix-bounds-check-bug-in-__register_chrdev_region.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Fix bounds check bug in __register_chrdev_region
From: Amos Waterland <apw@xxxxxxxxxx>
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.
I came across this in the context of the Xen virtual console driver, but I
imagine it causes a problem for any driver with the same major number but
different minor numbers as a driver that has registered ahead of it.
Signed-off-by: Amos Waterland <apw@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
diff -puN fs/char_dev.c~fix-bounds-check-bug-in-__register_chrdev_region fs/char_dev.c
--- a/fs/char_dev.c~fix-bounds-check-bug-in-__register_chrdev_region
+++ a/fs/char_dev.c
@@ -109,10 +109,13 @@ __register_chrdev_region(unsigned int ma
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) {
+ (((*cp)->baseminor < baseminor + minorct) ||
+ ((*cp)->baseminor + (*cp)->minorct > baseminor))) {
ret = -EBUSY;
goto out;
}
_
Patches currently in -mm which might be from apw@xxxxxxxxxx are
fix-bounds-check-bug-in-__register_chrdev_region.patch
-
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