[PATCH 5.15 653/731] drivers/md/md-bitmap: check the return value of md_bitmap_get_counter()

Greg Kroah-Hartman
2022-12-28T15:54:05Z

From: Li Zhong <floridsleeves@gmail.com>

[ Upstream commit 3bd548e5b819b8c0f2c9085de775c5c7bff9052f ]

Check the return value of md_bitmap_get_counter() in case it returns
NULL pointer, which will result in a null pointer dereference.

v2: update the check to include other dereference

Signed-off-by: Li Zhong <floridsleeves@gmail.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/md-bitmap.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 8cc11b1987ec..650bfccd066f 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -2196,20 +2196,23 @@ int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks,

if (set) {
bmc_new = md_bitmap_get_counter(&bitmap->counts, block, &new_blocks, 1);
- if (*bmc_new == 0) {
- /* need to set on-disk bits too. */
- sector_t end = block + new_blocks;
- sector_t start = block >> chunkshift;
- start <<= chunkshift;
- while (start < end) {
- md_bitmap_file_set_bit(bitmap, block);
- start += 1 << chunkshift;
+ if (bmc_new) {
+ if (*bmc_new == 0) {
+ /* need to set on-disk bits too. */
+ sector_t end = block + new_blocks;
+ sector_t start = block >> chunkshift;
+
+ start <<= chunkshift;
+ while (start < end) {
+ md_bitmap_file_set_bit(bitmap, block);
+ start += 1 << chunkshift;
+ }
+ *bmc_new = 2;
+ md_bitmap_count_page(&bitmap->counts, block, 1);
+ md_bitmap_set_pending(&bitmap->counts, block);
}
- *bmc_new = 2;
- md_bitmap_count_page(&bitmap->counts, block, 1);
- md_bitmap_set_pending(&bitmap->counts, block);
+ *bmc_new |= NEEDED_MASK;
}
- *bmc_new |= NEEDED_MASK;
if (new_blocks < old_blocks)
old_blocks = new_blocks;
}
--
2.35.1