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Subject[PATCH v3 1/4] chardev: add additional check for minor range overlap
Date
Current overlap checking cannot correctly handle
a case which is baseminor < existing baseminor &&
baseminor + minorct > existing baseminor + minorct.

Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
---
v1->v2:
- Split fix and cleanup patches.
- Remove printing minor range in chrdev_show().

fs/char_dev.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/char_dev.c b/fs/char_dev.c
index a279c58fe360..8a63cfa29005 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -159,6 +159,12 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
ret = -EBUSY;
goto out;
}
+
+ if (new_min < old_min && new_max > old_max) {
+ ret = -EBUSY;
+ goto out;
+ }
+
}

cd->next = *cp;
--
2.20.1
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