The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 60eb3b9c9f11206996f57cb89521824304b305ad Mon Sep 17 00:00:00 2001 From: Zhihao Cheng chengzhihao1@huawei.com Date: Mon, 27 Dec 2021 11:22:37 +0800 Subject: [PATCH] ubifs: Fix 'ui->dirty' race between do_tmpfile() and writeback work
'ui->dirty' is not protected by 'ui_mutex' in function do_tmpfile() which may race with ubifs_write_inode[wb_workfn] to access/update 'ui->dirty', finally dirty space is released twice.
open(O_TMPFILE) wb_workfn do_tmpfile ubifs_budget_space(ino_req = { .dirtied_ino = 1}) d_tmpfile // mark inode(tmpfile) dirty ubifs_jnl_update // without holding tmpfile's ui_mutex mark_inode_clean(ui) if (ui->dirty) ubifs_release_dirty_inode_budget(ui) // release first time ubifs_write_inode mutex_lock(&ui->ui_mutex) ubifs_release_dirty_inode_budget(ui) // release second time mutex_unlock(&ui->ui_mutex) ui->dirty = 0
Run generic/476 can reproduce following message easily (See reproducer in [Link]):
UBIFS error (ubi0:0 pid 2578): ubifs_assert_failed [ubifs]: UBIFS assert failed: c->bi.dd_growth >= 0, in fs/ubifs/budget.c:554 UBIFS warning (ubi0:0 pid 2578): ubifs_ro_mode [ubifs]: switched to read-only mode, error -22 Workqueue: writeback wb_workfn (flush-ubifs_0_0) Call Trace: ubifs_ro_mode+0x54/0x60 [ubifs] ubifs_assert_failed+0x4b/0x80 [ubifs] ubifs_release_budget+0x468/0x5a0 [ubifs] ubifs_release_dirty_inode_budget+0x53/0x80 [ubifs] ubifs_write_inode+0x121/0x1f0 [ubifs] ... wb_workfn+0x283/0x7b0
Fix it by holding tmpfile ubifs inode lock during ubifs_jnl_update(). Similar problem exists in whiteout renaming, but previous fix("ubifs: Rename whiteout atomically") has solved the problem.
Fixes: 474b93704f32163 ("ubifs: Implement O_TMPFILE") Link: https://bugzilla.kernel.org/show_bug.cgi?id=214765 Signed-off-by: Zhihao Cheng chengzhihao1@huawei.com Signed-off-by: Richard Weinberger richard@nod.at
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index f2a6b45bfdae..faca567ef06b 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -397,6 +397,32 @@ static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry) return ERR_PTR(err); }
+/** + * lock_2_inodes - a wrapper for locking two UBIFS inodes. + * @inode1: first inode + * @inode2: second inode + * + * We do not implement any tricks to guarantee strict lock ordering, because + * VFS has already done it for us on the @i_mutex. So this is just a simple + * wrapper function. + */ +static void lock_2_inodes(struct inode *inode1, struct inode *inode2) +{ + mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1); + mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2); +} + +/** + * unlock_2_inodes - a wrapper for unlocking two UBIFS inodes. + * @inode1: first inode + * @inode2: second inode + */ +static void unlock_2_inodes(struct inode *inode1, struct inode *inode2) +{ + mutex_unlock(&ubifs_inode(inode2)->ui_mutex); + mutex_unlock(&ubifs_inode(inode1)->ui_mutex); +} + static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir, struct dentry *dentry, umode_t mode) { @@ -404,7 +430,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir, struct ubifs_info *c = dir->i_sb->s_fs_info; struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1}; struct ubifs_budget_req ino_req = { .dirtied_ino = 1 }; - struct ubifs_inode *ui, *dir_ui = ubifs_inode(dir); + struct ubifs_inode *ui; int err, instantiated = 0; struct fscrypt_name nm;
@@ -452,18 +478,18 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir, instantiated = 1; mutex_unlock(&ui->ui_mutex);
- mutex_lock(&dir_ui->ui_mutex); + lock_2_inodes(dir, inode); err = ubifs_jnl_update(c, dir, &nm, inode, 1, 0); if (err) goto out_cancel; - mutex_unlock(&dir_ui->ui_mutex); + unlock_2_inodes(dir, inode);
ubifs_release_budget(c, &req);
return 0;
out_cancel: - mutex_unlock(&dir_ui->ui_mutex); + unlock_2_inodes(dir, inode); out_inode: make_bad_inode(inode); if (!instantiated) @@ -690,32 +716,6 @@ static int ubifs_dir_release(struct inode *dir, struct file *file) return 0; }
-/** - * lock_2_inodes - a wrapper for locking two UBIFS inodes. - * @inode1: first inode - * @inode2: second inode - * - * We do not implement any tricks to guarantee strict lock ordering, because - * VFS has already done it for us on the @i_mutex. So this is just a simple - * wrapper function. - */ -static void lock_2_inodes(struct inode *inode1, struct inode *inode2) -{ - mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1); - mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2); -} - -/** - * unlock_2_inodes - a wrapper for unlocking two UBIFS inodes. - * @inode1: first inode - * @inode2: second inode - */ -static void unlock_2_inodes(struct inode *inode1, struct inode *inode2) -{ - mutex_unlock(&ubifs_inode(inode2)->ui_mutex); - mutex_unlock(&ubifs_inode(inode1)->ui_mutex); -} - static int ubifs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) {