From: Gautham Ananthakrishna gautham.ananthakrishna@oracle.com

mainline inclusion from mainline-v5.15 commit 6f1b228529ae49b0f85ab89bcdb6c365df401558 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RDCV CVE: CVE-2021-47493

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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Encountered a race between ocfs2_test_bg_bit_allocatable() and jbd2_journal_put_journal_head() resulting in the below vmcore.

PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3" Call trace: panic oops_end no_context __bad_area_nosemaphore bad_area_nosemaphore __do_page_fault do_page_fault page_fault [exception RIP: ocfs2_block_group_find_clear_bits+316] ocfs2_block_group_find_clear_bits [ocfs2] ocfs2_cluster_group_search [ocfs2] ocfs2_search_chain [ocfs2] ocfs2_claim_suballoc_bits [ocfs2] __ocfs2_claim_clusters [ocfs2] ocfs2_claim_clusters [ocfs2] ocfs2_local_alloc_slide_window [ocfs2] ocfs2_reserve_local_alloc_bits [ocfs2] ocfs2_reserve_clusters_with_limit [ocfs2] ocfs2_reserve_clusters [ocfs2] ocfs2_lock_refcount_allocators [ocfs2] ocfs2_make_clusters_writable [ocfs2] ocfs2_replace_cow [ocfs2] ocfs2_refcount_cow [ocfs2] ocfs2_file_write_iter [ocfs2] lo_rw_aio loop_queue_work kthread_worker_fn kthread ret_from_fork

When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private NULL as jbd2_journal_put_journal_head() raced and released the jounal head from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead' to fix this race.

Link: https://lkml.kernel.org/r/1634820718-6043-1-git-send-email-gautham.ananthakr... Signed-off-by: Gautham Ananthakrishna gautham.ananthakrishna@oracle.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: rajesh.sivaramasubramaniom@oracle.com Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Changwei Ge gechangwei@live.cn Cc: Gang He ghe@suse.com Cc: Jun Piao piaojun@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

Conflicts: fs/ocfs2/suballoc.c Signed-off-by: liwei liwei728@huawei.com --- fs/ocfs2/suballoc.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index f7c972fbed6a..46e226d565ec 100644 --- a/fs/ocfs2/suballoc.c +++ b/fs/ocfs2/suballoc.c @@ -1266,7 +1266,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh, int nr) { struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data; - int ret; + int ret = 1;

if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap)) return 0; @@ -1274,13 +1274,17 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh, if (!buffer_jbd(bg_bh)) return 1;

- jbd_lock_bh_state(bg_bh); - bg = (struct ocfs2_group_desc *) bh2jh(bg_bh)->b_committed_data; - if (bg) - ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap); - else - ret = 1; - jbd_unlock_bh_state(bg_bh); + jbd_lock_bh_journal_head(bg_bh); + if (buffer_jbd(bg_bh)) { + jbd_lock_bh_state(bg_bh); + bg = (struct ocfs2_group_desc *) bh2jh(bg_bh)->b_committed_data; + if (bg) + ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap); + else + ret = 1; + jbd_unlock_bh_state(bg_bh); + } + jbd_unlock_bh_journal_head(bg_bh);

return ret; }