md/raid10: check slab-out-of-bounds in md_bitmap_get_counter

If we write a large number to md/bitmap_set_bits, md_bitmap_checkpage()
will return -EINVAL because 'page >= bitmap->pages', but the return value
was not checked immediately in md_bitmap_get_counter() in order to set
*blocks value and slab-out-of-bounds occurs.

Move check of 'page >= bitmap->pages' to md_bitmap_get_counter() and
return directly if true.

Fixes: ef4256733506 ("md/bitmap: optimise scanning of empty bitmaps.")
Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230515134808.3936750-2-linan666@huaweicloud.com

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index bc8d7565171d44f3027186fbf5a7b05714e49bda..358a06495902835ba7074ced43b83ef4c6d75024 100644 (file)
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -54,14 +54,7 @@ __acquires(bitmap->lock)
 {
        unsigned char *mappage;
 
-       if (page >= bitmap->pages) {
-               /* This can happen if bitmap_start_sync goes beyond
-                * End-of-device while looking for a whole page.
-                * It is harmless.
-                */
-               return -EINVAL;
-       }
-
+       WARN_ON_ONCE(page >= bitmap->pages);
        if (bitmap->bp[page].hijacked) /* it's hijacked, don't try to alloc */
                return 0;
 
@@ -1387,6 +1380,14 @@ __acquires(bitmap->lock)
        sector_t csize;
        int err;
 
+       if (page >= bitmap->pages) {
+               /*
+                * This can happen if bitmap_start_sync goes beyond
+                * End-of-device while looking for a whole page or
+                * user set a huge number to sysfs bitmap_set_bits.
+                */
+               return NULL;
+       }
        err = md_bitmap_checkpage(bitmap, page, create, 0);
 
        if (bitmap->bp[page].hijacked ||