Patch "drivers/md/md-bitmap: check the return value of md_bitmap_get_counter()" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drivers/md/md-bitmap: check the return value of md_bitmap_get_counter()

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drivers-md-md-bitmap-check-the-return-value-of-md_bi.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit abc8c13a93c1cc179f2a2f4d3eeeb9995233b562
Author: Li Zhong <floridsleeves@xxxxxxxxx>
Date:   Fri Sep 16 16:33:05 2022 -0700

    drivers/md/md-bitmap: check the return value of md_bitmap_get_counter()
    
    [ 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@xxxxxxxxx>
    Signed-off-by: Song Liu <song@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index a95e20c3d0d4..72c30c99b29d 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -2200,20 +2200,23 @@ 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;
 		}