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    Subject[PATCH AUTOSEL 6.0 36/73] drivers/md/md-bitmap: check the return value of md_bitmap_get_counter()
    Date
    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 bf6dffadbe6f..63ece30114e5 100644
    --- a/drivers/md/md-bitmap.c
    +++ b/drivers/md/md-bitmap.c
    @@ -2195,20 +2195,23 @@ 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
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