From: xiaoshoukui <xiaoshoukui@gmail.com> stable inclusion from stable-v4.19.293 commit 7c93b89cd46636b5e74c12fa21dd86167bc6ea8d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICYJ02 CVE: CVE-2023-53339 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 29eefa6d0d07e185f7bfe9576f91e6dba98189c2 upstream. Pausing and canceling balance can race to interrupt balance lead to BUG_ON panic in btrfs_cancel_balance. The BUG_ON condition in btrfs_cancel_balance does not take this race scenario into account. However, the race condition has no other side effects. We can fix that. Reproducing it with panic trace like this: kernel BUG at fs/btrfs/volumes.c:4618! RIP: 0010:btrfs_cancel_balance+0x5cf/0x6a0 Call Trace: <TASK> ? do_nanosleep+0x60/0x120 ? hrtimer_nanosleep+0xb7/0x1a0 ? sched_core_clone_cookie+0x70/0x70 btrfs_ioctl_balance_ctl+0x55/0x70 btrfs_ioctl+0xa46/0xd20 __x64_sys_ioctl+0x7d/0xa0 do_syscall_64+0x38/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Race scenario as follows:

mutex_unlock(&fs_info->balance_mutex); -------------------- .......issue pause and cancel req in another thread -------------------- ret = __btrfs_balance(fs_info);

mutex_lock(&fs_info->balance_mutex); if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) { btrfs_info(fs_info, "balance: paused"); btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED); }

CC: stable@vger.kernel.org # 4.19+ Signed-off-by: xiaoshoukui <xiaoshoukui@ruijie.com.cn> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> --- fs/btrfs/volumes.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index abda01208a69..2fce0ea3bc99 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4089,8 +4089,7 @@ int btrfs_cancel_balance(struct btrfs_fs_info *fs_info) } } - BUG_ON(fs_info->balance_ctl || - test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)); + ASSERT(!test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)); atomic_dec(&fs_info->balance_cancel_req); mutex_unlock(&fs_info->balance_mutex); return 0; -- 2.39.2