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Aurelien Aptel 2938651d36 CIFS: fix POSIX lock leak and invalid ptr deref [ Upstream commit `bc31d0cdcf` ] We have a customer reporting crashes in lock_get_status() with many "Leaked POSIX lock" messages preceeding the crash. Leaked POSIX lock on dev=0x0:0x56 ... Leaked POSIX lock on dev=0x0:0x56 ... Leaked POSIX lock on dev=0x0:0x56 ... Leaked POSIX lock on dev=0x0:0x53 ... Leaked POSIX lock on dev=0x0:0x53 ... Leaked POSIX lock on dev=0x0:0x53 ... Leaked POSIX lock on dev=0x0:0x53 ... POSIX: fl_owner=ffff8900e7b79380 fl_flags=0x1 fl_type=0x1 fl_pid=20709 Leaked POSIX lock on dev=0x0:0x4b ino... Leaked locks on dev=0x0:0x4b ino=0xf911400000029: POSIX: fl_owner=ffff89f41c870e00 fl_flags=0x1 fl_type=0x1 fl_pid=19592 stack segment: 0000 [#1] SMP Modules linked in: binfmt_misc msr tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag rpcsec_gss_krb5 arc4 ecb auth_rpcgss nfsv4 md4 nfs nls_utf8 lockd grace cifs sunrpc ccm dns_resolver fscache af_packet iscsi_ibft iscsi_boot_sysfs vmw_vsock_vmci_transport vsock xfs libcrc32c sb_edac edac_core crct10dif_pclmul crc32_pclmul ghash_clmulni_intel drbg ansi_cprng vmw_balloon aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd joydev pcspkr vmxnet3 i2c_piix4 vmw_vmci shpchp fjes processor button ac btrfs xor raid6_pq sr_mod cdrom ata_generic sd_mod ata_piix vmwgfx crc32c_intel drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm serio_raw ahci libahci drm libata vmw_pvscsi sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_mod autofs4 Supported: Yes CPU: 6 PID: 28250 Comm: lsof Not tainted 4.4.156-94.64-default #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016 task: ffff88a345f28740 ti: ffff88c74005c000 task.ti: ffff88c74005c000 RIP: 0010:[<ffffffff8125dcab>] [<ffffffff8125dcab>] lock_get_status+0x9b/0x3b0 RSP: 0018:ffff88c74005fd90 EFLAGS: 00010202 RAX: ffff89bde83e20ae RBX: ffff89e870003d18 RCX: 0000000049534f50 RDX: ffffffff81a3541f RSI: ffffffff81a3544e RDI: ffff89bde83e20ae RBP: 0026252423222120 R08: 0000000020584953 R09: 000000000000ffff R10: 0000000000000000 R11: ffff88c74005fc70 R12: ffff89e5ca7b1340 R13: 00000000000050e5 R14: ffff89e870003d30 R15: ffff89e5ca7b1340 FS: 00007fafd64be800(0000) GS:ffff89f41fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001c80018 CR3: 000000a522048000 CR4: 0000000000360670 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000208 ffffffff81a3d6b6 ffff89e870003d30 ffff89e870003d18 ffff89e5ca7b1340 ffff89f41738d7c0 ffff89e870003d30 ffff89e5ca7b1340 ffffffff8125e08f 0000000000000000 ffff89bc22b67d00 ffff88c74005ff28 Call Trace: [<ffffffff8125e08f>] locks_show+0x2f/0x70 [<ffffffff81230ad1>] seq_read+0x251/0x3a0 [<ffffffff81275bbc>] proc_reg_read+0x3c/0x70 [<ffffffff8120e456>] __vfs_read+0x26/0x140 [<ffffffff8120e9da>] vfs_read+0x7a/0x120 [<ffffffff8120faf2>] SyS_read+0x42/0xa0 [<ffffffff8161cbc3>] entry_SYSCALL_64_fastpath+0x1e/0xb7 When Linux closes a FD (close(), close-on-exec, dup2(), ...) it calls filp_close() which also removes all posix locks. The lock struct is initialized like so in filp_close() and passed down to cifs ... lock.fl_type = F_UNLCK; lock.fl_flags = FL_POSIX \| FL_CLOSE; lock.fl_start = 0; lock.fl_end = OFFSET_MAX; ... Note the FL_CLOSE flag, which hints the VFS code that this unlocking is done for closing the fd. filp_close() locks_remove_posix(filp, id); vfs_lock_file(filp, F_SETLK, &lock, NULL); return filp->f_op->lock(filp, cmd, fl) => cifs_lock() rc = cifs_setlk(file, flock, type, wait_flag, posix_lck, lock, unlock, xid); rc = server->ops->mand_unlock_range(cfile, flock, xid); if (flock->fl_flags & FL_POSIX && !rc) rc = locks_lock_file_wait(file, flock) Notice how we don't call locks_lock_file_wait() which does the generic VFS lock/unlock/wait work on the inode if rc != 0. If we are closing the handle, the SMB server is supposed to remove any locks associated with it. Similarly, cifs.ko frees and wakes up any lock and lock waiter when closing the file: cifs_close() cifsFileInfo_put(file->private_data) /* * Delete any outstanding lock records. We'll lose them when the file * is closed anyway. */ down_write(&cifsi->lock_sem); list_for_each_entry_safe(li, tmp, &cifs_file->llist->locks, llist) { list_del(&li->llist); cifs_del_lock_waiters(li); kfree(li); } list_del(&cifs_file->llist->llist); kfree(cifs_file->llist); up_write(&cifsi->lock_sem); So we can safely ignore unlocking failures in cifs_lock() if they happen with the FL_CLOSE flag hint set as both the server and the client take care of it during the actual closing. This is not a proper fix for the unlocking failure but it's safe and it seems to prevent the lock leakages and crashes the customer experiences. Signed-off-by: Aurelien Aptel <aaptel@suse.com> Signed-off-by: NeilBrown <neil@brown.name> Signed-off-by: Steve French <stfrench@microsoft.com> Acked-by: Pavel Shilovsky <pshilov@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		2019-04-05 22:32:55 +02:00
arch	arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals	2019-04-05 22:32:55 +02:00
block	blk-mq: insert rq with DONTPREP to hctx dispatch list when requeue	2019-03-23 20:09:45 +01:00
certs	export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()	2018-08-22 23:21:44 +09:00
crypto	crypto: testmgr - skip crc32c context test for ahash algorithms	2019-03-23 20:09:55 +01:00
Documentation	KVM: Reject device ioctls from processes other than the VM's creator	2019-04-03 06:26:29 +02:00
drivers	tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped	2019-04-05 22:32:55 +02:00
firmware	kbuild: remove all dummy assignments to obj-	2017-11-18 11:46:06 +09:00
fs	CIFS: fix POSIX lock leak and invalid ptr deref	2019-04-05 22:32:55 +02:00
include	drivers: base: Helpers for adding device connection descriptions	2019-04-03 06:26:30 +02:00
init	Revert "mm: use early_pfn_to_nid in page_ext_init"	2019-03-23 20:09:46 +01:00
ipc	ipc/shm.c: use ERR_CAST() for shm_lock() error return	2018-10-05 16:32:04 -07:00
kernel	bpf: do not restore dst_reg when cur_state is freed	2019-04-03 06:26:30 +02:00
lib	rhashtable: Still do rehash when we get EEXIST	2019-04-03 06:26:17 +02:00
LICENSES	LICENSES: Remove CC-BY-SA-4.0 license text	2018-10-18 11:28:50 +02:00
mm	mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate	2019-04-03 06:26:28 +02:00
net	net: sched: fix cleanup NULL pointer exception in act_mirr	2019-04-03 06:26:19 +02:00
samples	samples: mei: use /dev/mei0 instead of /dev/mei	2019-02-15 08:10:11 +01:00
scripts	kbuild: modversions: Fix relative CRC byte order interpretation	2019-04-03 06:26:23 +02:00
security	security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock	2019-03-23 20:10:06 +01:00
sound	ALSA: hda/realtek - Fix speakers on Acer Predator Helios 500 Ryzen laptops	2019-04-03 06:26:23 +02:00
tools	objtool: Query pkg-config for libelf location	2019-04-03 06:26:28 +02:00
usr	initramfs: move gen_initramfs_list.sh from scripts/ to usr/	2018-08-22 23:21:44 +09:00
virt	KVM: Reject device ioctls from processes other than the VM's creator	2019-04-03 06:26:29 +02:00
.clang-format	clang-format: Set IndentWrappedFunctionNames false	2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	libnvdimm-for-4.19_misc	2018-08-25 18:13:10 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	9p: remove Ron Minnich from MAINTAINERS	2018-08-17 16:20:26 -07:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt	2018-08-02 08:06:55 +09:00
MAINTAINERS	MAINTAINERS: Add Sasha as a stable branch maintainer	2018-12-01 09:37:25 +01:00
Makefile	Linux 4.19.33	2019-04-03 06:26:31 +02:00
README	Docs: Added a pointer to the formatted docs to README	2018-03-21 09:02:53 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.