[PATCH 6.4 033/800] md/raid10: check slab-out-of-bounds in md_bitmap_get_counter

Greg Kroah-Hartman
2023-07-16T19:54:21Z

From: Li Nan <linan122@huawei.com>

[ Upstream commit 301867b1c16805aebbc306aafa6ecdc68b73c7e5 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/md-bitmap.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index bc8d7565171d4..358a064959028 100644
--- 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 ||
--
2.39.2