From: Yang Erkun <yangerkun@huawei.com> hulk inclusion category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9787 -------------------------------- Lingfeng identified a bug and suggested two solutions, but both appear to have issues. Generally, we cannot release flc_lock while iterating over the file lock list to avoid use-after-free (UAF) problems with file locks. However, functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot adhere to this rule because recover_lock or nfs4_lock_delegation_recall may take a long time. To resolve this, NFS switches to using nfsi->rwsem for the same protection, and nfs_reclaim_locks follows this approach. Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead, this is inadequate since a single inode can have multiple nfs4_state instances. Therefore, the fix is to also use nfsi->rwsem in this case. Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update"), the functions nfs4_locku_done and nfs4_lock_done also break this rule because they call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding this protection could cause many deadlocks, so instead, the call to locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update"), it has been resolved after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering state recovery") because all slots are drained before calling nfs4_do_reclaim, which prevents concurrent stateid changes along this path. Also, nfs_delegation_claim_locks does not cause this concurrency either since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is sent, so nfs4_lock_done is not called. Therefore, nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first time the stateid is set. Reported-by: Li Lingfeng <lilingfeng3@huawei.com> Closes: https://lore.kernel.org/all/20250419085709.1452492-1-lilingfeng3@huawei.com/ Closes: https://lore.kernel.org/all/20250715030559.2906634-1-lilingfeng3@huawei.com/ Fixes: c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update") Signed-off-by: Yang Erkun <yangerkun@huawei.com> Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> --- fs/nfs/delegation.c | 9 ++++++++- fs/nfs/nfs4proc.c | 22 +++++++++++----------- include/linux/nfs_xdr.h | 1 - 3 files changed, 19 insertions(+), 13 deletions(-) diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c index bbd582d8a7dc..fb93b9edb39b 100644 --- a/fs/nfs/delegation.c +++ b/fs/nfs/delegation.c @@ -143,35 +143,42 @@ int nfs4_check_delegation(struct inode *inode, fmode_t flags) } static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid) { struct inode *inode = state->inode; + struct nfs_inode *nfsi = NFS_I(inode); struct file_lock *fl; struct file_lock_context *flctx = locks_inode_context(inode); struct list_head *list; int status = 0; if (flctx == NULL) goto out; list = &flctx->flc_posix; + + /* Guard against delegation returns and new lock/unlock calls */ + down_write(&nfsi->rwsem); spin_lock(&flctx->flc_lock); restart: list_for_each_entry(fl, list, fl_list) { if (nfs_file_open_context(fl->fl_file)->state != state) continue; spin_unlock(&flctx->flc_lock); status = nfs4_lock_delegation_recall(fl, state, stateid); - if (status < 0) + if (status < 0) { + up_write(&nfsi->rwsem); goto out; + } spin_lock(&flctx->flc_lock); } if (list == &flctx->flc_posix) { list = &flctx->flc_flock; goto restart; } spin_unlock(&flctx->flc_lock); + up_write(&nfsi->rwsem); out: return status; } static int nfs_delegation_claim_opens(struct inode *inode, diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 58739de4e793..f7163d9de438 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -6953,11 +6953,10 @@ static void nfs4_locku_done(struct rpc_task *task, void *data) if (!nfs4_sequence_done(task, &calldata->res.seq_res)) return; switch (task->tk_status) { case 0: renew_lease(calldata->server, calldata->timestamp); - locks_lock_inode_wait(calldata->lsp->ls_state->inode, &calldata->fl); if (nfs4_update_lock_stateid(calldata->lsp, &calldata->res.stateid)) break; fallthrough; case -NFS4ERR_ADMIN_REVOKED: @@ -7217,15 +7216,10 @@ static void nfs4_lock_done(struct rpc_task *task, void *calldata) data->rpc_status = task->tk_status; switch (task->tk_status) { case 0: renew_lease(NFS_SERVER(d_inode(data->ctx->dentry)), data->timestamp); - if (data->arg.new_lock && !data->cancelled) { - data->fl.fl_flags &= ~(FL_SLEEP | FL_ACCESS); - if (locks_lock_inode_wait(lsp->ls_state->inode, &data->fl) < 0) - goto out_restart; - } if (data->arg.new_lock_owner != 0) { nfs_confirm_seqid(&lsp->ls_seqid, 0); nfs4_stateid_copy(&lsp->ls_stateid, &data->res.stateid); set_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags); } else if (!nfs4_update_lock_stateid(lsp, &data->res.stateid)) @@ -7330,15 +7324,14 @@ static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *f nfs4_init_sequence(&data->arg.seq_args, &data->res.seq_res, 1, recovery_type > NFS_LOCK_NEW); msg.rpc_argp = &data->arg; msg.rpc_resp = &data->res; task_setup_data.callback_data = data; - if (recovery_type > NFS_LOCK_NEW) { - if (recovery_type == NFS_LOCK_RECLAIM) - data->arg.reclaim = NFS_LOCK_RECLAIM; - } else - data->arg.new_lock = 1; + + if (recovery_type == NFS_LOCK_RECLAIM) + data->arg.reclaim = NFS_LOCK_RECLAIM; + task = rpc_run_task(&task_setup_data); if (IS_ERR(task)) return PTR_ERR(task); ret = rpc_wait_for_completion_task(task); if (ret == 0) { @@ -7446,10 +7439,17 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock goto out; } up_read(&nfsi->rwsem); mutex_unlock(&sp->so_delegreturn_mutex); status = _nfs4_do_setlk(state, cmd, request, NFS_LOCK_NEW); + if (status) + goto out; + + down_read(&nfsi->rwsem); + request->fl_flags &= ~(FL_SLEEP | FL_ACCESS); + status = locks_lock_inode_wait(state->inode, request); + up_read(&nfsi->rwsem); out: request->fl_flags = fl_flags; return status; } diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h index 5d2ad7bd92c3..ed27379ff302 100644 --- a/include/linux/nfs_xdr.h +++ b/include/linux/nfs_xdr.h @@ -561,11 +561,10 @@ struct nfs_lock_args { struct nfs_seqid * open_seqid; nfs4_stateid open_stateid; struct nfs_lowner lock_owner; unsigned char block : 1; unsigned char reclaim : 1; - unsigned char new_lock : 1; unsigned char new_lock_owner : 1; }; struct nfs_lock_res { struct nfs4_sequence_res seq_res; -- 2.52.0