From: Li Zhong <floridsleeves@gmail.com> stable inclusion from stable-v4.19.270 commit 21e9aac9a74d30907d44bae0d24c036cb3819406 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICYQP9 CVE: CVE-2022-50402 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ------------------ [ 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> Signed-off-by: Zheng Qixing <zhengqixing@huawei.com> --- 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 37d6fefd4c6e..3c89be54c2f6 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -2194,20 +2194,23 @@ 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; } -- 2.39.2