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authorChristophe JAILLET <christophe.jaillet@wanadoo.fr>2022-03-26 15:50:46 +0100
committerJens Axboe <axboe@kernel.dk>2022-03-28 06:34:30 -0600
commitd1868328dec5ae2cf210111025fcbc71f78dd5ca (patch)
tree8dbb62158a9b259e4f838401fcffeb08e6c707c9 /block/genhd.c
parent15583a563cd5a7358e975599b7de7caacd9e9ce9 (diff)
block: Fix the maximum minor value is blk_alloc_ext_minor()
ida_alloc_range(..., min, max, ...) returns values from min to max, inclusive. So, NR_EXT_DEVT is a valid idx returned by blk_alloc_ext_minor(). This is an issue because in device_add_disk(), this value is used in: ddev->devt = MKDEV(disk->major, disk->first_minor); and NR_EXT_DEVT is '(1 << MINORBITS)'. So, should 'disk->first_minor' be NR_EXT_DEVT, it would overflow. Fixes: 22ae8ce8b892 ("block: simplify bdev/disk lookup in blkdev_get") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/cc17199798312406b90834e433d2cefe8266823d.1648306232.git.christophe.jaillet@wanadoo.fr Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/genhd.c')
-rw-r--r--block/genhd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/block/genhd.c b/block/genhd.c
index 8244f09e058d..19b8a6e7a13b 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -335,7 +335,7 @@ int blk_alloc_ext_minor(void)
{
int idx;
- idx = ida_alloc_range(&ext_devt_ida, 0, NR_EXT_DEVT, GFP_KERNEL);
+ idx = ida_alloc_range(&ext_devt_ida, 0, NR_EXT_DEVT - 1, GFP_KERNEL);
if (idx == -ENOSPC)
return -EBUSY;
return idx;