The patch below does not apply to the 4.14-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 236ebc20d9afc5e9ff52f3cf3f365a91583aac10 Mon Sep 17 00:00:00 2001

From: Filipe Manana fdmanana@suse.com Date: Tue, 10 Mar 2020 12:13:53 +0000 Subject: [PATCH] btrfs: fix log context list corruption after rename whiteout error

During a rename whiteout, if btrfs_whiteout_for_rename() returns an error we can end up returning from btrfs_rename() with the log context object still in the root's log context list - this happens if 'sync_log' was set to true before we called btrfs_whiteout_for_rename() and it is dangerous because we end up with a corrupt linked list (root->log_ctxs) as the log context object was allocated on the stack.

After btrfs_rename() returns, any task that is running btrfs_sync_log() concurrently can end up crashing because that linked list is traversed by btrfs_sync_log() (through btrfs_remove_all_log_ctxs()). That results in the same issue that commit e6c617102c7e4 ("Btrfs: fix log context list corruption after rename exchange operation") fixed.

Fixes: d4682ba03ef618 ("Btrfs: sync log after logging new name") CC: stable@vger.kernel.org # 4.19+ Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 27076ebadb36..d267eb5caa7b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9496,6 +9496,10 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry, ret = btrfs_sync_log(trans, BTRFS_I(old_inode)->root, &ctx); if (ret) commit_transaction = true; + } else if (sync_log) { + mutex_lock(&root->log_mutex); + list_del(&ctx.list); + mutex_unlock(&root->log_mutex); } if (commit_transaction) { ret = btrfs_commit_transaction(trans);