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![Stefano Brivio](/assets/img/avatar_default.png)
smb{2,3}_create_lease_buf() store a lease key in the lease
context for later usage on a lease break.
In most paths, the key is currently sourced from data that
happens to be on the stack near local variables for oplock in
SMB2_open() callers, e.g. from open_shroot(), whereas
smb2_open_file() properly allocates space on its stack for it.
The address of those local variables holding the oplock is then
passed to create_lease_buf handlers via SMB2_open(), and 16
bytes near oplock are used. This causes a stack out-of-bounds
access as reported by KASAN on SMB2.1 and SMB3 mounts (first
out-of-bounds access is shown here):
[ 111.528823] BUG: KASAN: stack-out-of-bounds in smb3_create_lease_buf+0x399/0x3b0 [cifs]
[ 111.530815] Read of size 8 at addr ffff88010829f249 by task mount.cifs/985
[ 111.532838] CPU: 3 PID: 985 Comm: mount.cifs Not tainted 4.18.0-rc3+ #91
[ 111.534656] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[ 111.536838] Call Trace:
[ 111.537528] dump_stack+0xc2/0x16b
[ 111.540890] print_address_description+0x6a/0x270
[ 111.542185] kasan_report+0x258/0x380
[ 111.544701] smb3_create_lease_buf+0x399/0x3b0 [cifs]
[ 111.546134] SMB2_open+0x1ef8/0x4b70 [cifs]
[ 111.575883] open_shroot+0x339/0x550 [cifs]
[ 111.591969] smb3_qfs_tcon+0x32c/0x1e60 [cifs]
[ 111.617405] cifs_mount+0x4f3/0x2fc0 [cifs]
[ 111.674332] cifs_smb3_do_mount+0x263/0xf10 [cifs]
[ 111.677915] mount_fs+0x55/0x2b0
[ 111.679504] vfs_kern_mount.part.22+0xaa/0x430
[ 111.684511] do_mount+0xc40/0x2660
[ 111.698301] ksys_mount+0x80/0xd0
[ 111.701541] do_syscall_64+0x14e/0x4b0
[ 111.711807] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 111.713665] RIP: 0033:0x7f372385b5fa
[ 111.715311] Code: 48 8b 0d 99 78 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 66 78 2c 00 f7 d8 64 89 01 48
[ 111.720330] RSP: 002b:00007ffff27049d8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
[ 111.722601] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f372385b5fa
[ 111.724842] RDX: 000055c2ecdc73b2 RSI: 000055c2ecdc73f9 RDI: 00007ffff270580f
[ 111.727083] RBP: 00007ffff2705804 R08: 000055c2ee976060 R09: 0000000000001000
[ 111.729319] R10: 0000000000000000 R11: 0000000000000206 R12: 00007f3723f4d000
[ 111.731615] R13: 000055c2ee976060 R14: 00007f3723f4f90f R15: 0000000000000000
[ 111.735448] The buggy address belongs to the page:
[ 111.737420] page:ffffea000420a7c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
[ 111.739890] flags: 0x17ffffc0000000()
[ 111.741750] raw: 0017ffffc0000000 0000000000000000 dead000000000200 0000000000000000
[ 111.744216] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[ 111.746679] page dumped because: kasan: bad access detected
[ 111.750482] Memory state around the buggy address:
[ 111.752562] ffff88010829f100: 00 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00
[ 111.754991] ffff88010829f180: 00 00 f2 f2 00 00 00 00 00 00 00 00 00 00 00 00
[ 111.757401] >ffff88010829f200: 00 00 00 00 00 f1 f1 f1 f1 01 f2 f2 f2 f2 f2 f2
[ 111.759801] ^
[ 111.762034] ffff88010829f280: f2 02 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00
[ 111.764486] ffff88010829f300: f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[ 111.766913] ==================================================================
Lease keys are however already generated and stored in fid data
on open and create paths: pass them down to the lease context
creation handlers and use them.
Suggested-by: Aurélien Aptel <aaptel@suse.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Fixes: b8c32dbb0d
("CIFS: Request SMB2.1 leases")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
283 lines
7.5 KiB
C
283 lines
7.5 KiB
C
/*
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* fs/cifs/smb2file.c
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*
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* Copyright (C) International Business Machines Corp., 2002, 2011
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* Author(s): Steve French (sfrench@us.ibm.com),
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* Pavel Shilovsky ((pshilovsky@samba.org) 2012
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/fs.h>
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#include <linux/stat.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include <asm/div64.h>
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#include "cifsfs.h"
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#include "cifspdu.h"
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#include "cifsglob.h"
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#include "cifsproto.h"
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#include "cifs_debug.h"
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#include "cifs_fs_sb.h"
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#include "cifs_unicode.h"
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#include "fscache.h"
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#include "smb2proto.h"
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int
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smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms,
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__u32 *oplock, FILE_ALL_INFO *buf)
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{
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int rc;
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__le16 *smb2_path;
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struct smb2_file_all_info *smb2_data = NULL;
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__u8 smb2_oplock;
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struct cifs_fid *fid = oparms->fid;
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struct network_resiliency_req nr_ioctl_req;
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smb2_path = cifs_convert_path_to_utf16(oparms->path, oparms->cifs_sb);
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if (smb2_path == NULL) {
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rc = -ENOMEM;
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goto out;
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}
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smb2_data = kzalloc(sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
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GFP_KERNEL);
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if (smb2_data == NULL) {
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rc = -ENOMEM;
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goto out;
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}
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oparms->desired_access |= FILE_READ_ATTRIBUTES;
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smb2_oplock = SMB2_OPLOCK_LEVEL_BATCH;
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rc = SMB2_open(xid, oparms, smb2_path, &smb2_oplock, smb2_data, NULL,
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NULL);
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if (rc)
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goto out;
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if (oparms->tcon->use_resilient) {
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nr_ioctl_req.Timeout = 0; /* use server default (120 seconds) */
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nr_ioctl_req.Reserved = 0;
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rc = SMB2_ioctl(xid, oparms->tcon, fid->persistent_fid,
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fid->volatile_fid, FSCTL_LMR_REQUEST_RESILIENCY,
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true /* is_fsctl */,
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(char *)&nr_ioctl_req, sizeof(nr_ioctl_req),
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NULL, NULL /* no return info */);
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if (rc == -EOPNOTSUPP) {
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cifs_dbg(VFS,
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"resiliency not supported by server, disabling\n");
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oparms->tcon->use_resilient = false;
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} else if (rc)
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cifs_dbg(FYI, "error %d setting resiliency\n", rc);
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rc = 0;
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}
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if (buf) {
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/* open response does not have IndexNumber field - get it */
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rc = SMB2_get_srv_num(xid, oparms->tcon, fid->persistent_fid,
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fid->volatile_fid,
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&smb2_data->IndexNumber);
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if (rc) {
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/* let get_inode_info disable server inode numbers */
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smb2_data->IndexNumber = 0;
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rc = 0;
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}
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move_smb2_info_to_cifs(buf, smb2_data);
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}
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*oplock = smb2_oplock;
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out:
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kfree(smb2_data);
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kfree(smb2_path);
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return rc;
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}
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int
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smb2_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock,
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const unsigned int xid)
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{
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int rc = 0, stored_rc;
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unsigned int max_num, num = 0, max_buf;
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struct smb2_lock_element *buf, *cur;
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struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
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struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
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struct cifsLockInfo *li, *tmp;
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__u64 length = 1 + flock->fl_end - flock->fl_start;
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struct list_head tmp_llist;
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INIT_LIST_HEAD(&tmp_llist);
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/*
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* Accessing maxBuf is racy with cifs_reconnect - need to store value
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* and check it for zero before using.
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*/
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max_buf = tcon->ses->server->maxBuf;
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if (!max_buf)
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return -EINVAL;
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max_num = max_buf / sizeof(struct smb2_lock_element);
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buf = kcalloc(max_num, sizeof(struct smb2_lock_element), GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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cur = buf;
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down_write(&cinode->lock_sem);
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list_for_each_entry_safe(li, tmp, &cfile->llist->locks, llist) {
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if (flock->fl_start > li->offset ||
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(flock->fl_start + length) <
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(li->offset + li->length))
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continue;
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if (current->tgid != li->pid)
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continue;
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if (cinode->can_cache_brlcks) {
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/*
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* We can cache brlock requests - simply remove a lock
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* from the file's list.
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*/
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list_del(&li->llist);
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cifs_del_lock_waiters(li);
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kfree(li);
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continue;
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}
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cur->Length = cpu_to_le64(li->length);
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cur->Offset = cpu_to_le64(li->offset);
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cur->Flags = cpu_to_le32(SMB2_LOCKFLAG_UNLOCK);
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/*
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* We need to save a lock here to let us add it again to the
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* file's list if the unlock range request fails on the server.
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*/
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list_move(&li->llist, &tmp_llist);
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if (++num == max_num) {
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stored_rc = smb2_lockv(xid, tcon,
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cfile->fid.persistent_fid,
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cfile->fid.volatile_fid,
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current->tgid, num, buf);
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if (stored_rc) {
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/*
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* We failed on the unlock range request - add
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* all locks from the tmp list to the head of
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* the file's list.
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*/
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cifs_move_llist(&tmp_llist,
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&cfile->llist->locks);
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rc = stored_rc;
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} else
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/*
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* The unlock range request succeed - free the
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* tmp list.
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*/
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cifs_free_llist(&tmp_llist);
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cur = buf;
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num = 0;
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} else
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cur++;
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}
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if (num) {
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stored_rc = smb2_lockv(xid, tcon, cfile->fid.persistent_fid,
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cfile->fid.volatile_fid, current->tgid,
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num, buf);
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if (stored_rc) {
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cifs_move_llist(&tmp_llist, &cfile->llist->locks);
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rc = stored_rc;
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} else
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cifs_free_llist(&tmp_llist);
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}
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up_write(&cinode->lock_sem);
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kfree(buf);
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return rc;
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}
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static int
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smb2_push_mand_fdlocks(struct cifs_fid_locks *fdlocks, const unsigned int xid,
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struct smb2_lock_element *buf, unsigned int max_num)
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{
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int rc = 0, stored_rc;
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struct cifsFileInfo *cfile = fdlocks->cfile;
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struct cifsLockInfo *li;
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unsigned int num = 0;
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struct smb2_lock_element *cur = buf;
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struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
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list_for_each_entry(li, &fdlocks->locks, llist) {
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cur->Length = cpu_to_le64(li->length);
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cur->Offset = cpu_to_le64(li->offset);
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cur->Flags = cpu_to_le32(li->type |
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SMB2_LOCKFLAG_FAIL_IMMEDIATELY);
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if (++num == max_num) {
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stored_rc = smb2_lockv(xid, tcon,
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cfile->fid.persistent_fid,
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cfile->fid.volatile_fid,
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current->tgid, num, buf);
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if (stored_rc)
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rc = stored_rc;
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cur = buf;
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num = 0;
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} else
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cur++;
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}
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if (num) {
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stored_rc = smb2_lockv(xid, tcon,
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cfile->fid.persistent_fid,
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cfile->fid.volatile_fid,
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current->tgid, num, buf);
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if (stored_rc)
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rc = stored_rc;
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}
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return rc;
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}
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int
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smb2_push_mandatory_locks(struct cifsFileInfo *cfile)
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{
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int rc = 0, stored_rc;
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unsigned int xid;
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unsigned int max_num, max_buf;
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struct smb2_lock_element *buf;
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struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
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struct cifs_fid_locks *fdlocks;
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xid = get_xid();
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/*
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* Accessing maxBuf is racy with cifs_reconnect - need to store value
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* and check it for zero before using.
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*/
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max_buf = tlink_tcon(cfile->tlink)->ses->server->maxBuf;
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if (max_buf < sizeof(struct smb2_lock_element)) {
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free_xid(xid);
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return -EINVAL;
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}
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max_num = max_buf / sizeof(struct smb2_lock_element);
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buf = kcalloc(max_num, sizeof(struct smb2_lock_element), GFP_KERNEL);
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if (!buf) {
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free_xid(xid);
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return -ENOMEM;
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}
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list_for_each_entry(fdlocks, &cinode->llist, llist) {
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stored_rc = smb2_push_mand_fdlocks(fdlocks, xid, buf, max_num);
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if (stored_rc)
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rc = stored_rc;
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}
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kfree(buf);
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free_xid(xid);
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return rc;
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}
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