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Eric W. Biederman 117433236a exec: Transform exec_update_mutex into a rw_semaphore 
[ Upstream commit f7cfd871ae ]

Recently syzbot reported[0] that there is a deadlock amongst the users
of exec_update_mutex.  The problematic lock ordering found by lockdep
was:

   perf_event_open  (exec_update_mutex -> ovl_i_mutex)
   chown            (ovl_i_mutex       -> sb_writes)
   sendfile         (sb_writes         -> p->lock)
     by reading from a proc file and writing to overlayfs
   proc_pid_syscall (p->lock           -> exec_update_mutex)

While looking at possible solutions it occured to me that all of the
users and possible users involved only wanted to state of the given
process to remain the same.  They are all readers.  The only writer is
exec.

There is no reason for readers to block on each other.  So fix
this deadlock by transforming exec_update_mutex into a rw_semaphore
named exec_update_lock that only exec takes for writing.

Cc: Jann Horn <jannh@google.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Christopher Yeoh <cyeoh@au1.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Fixes: eea9673250 ("exec: Add exec_update_mutex to replace cred_guard_mutex")
[0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com
Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com
Link: https://lkml.kernel.org/r/87ft4mbqen.fsf@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2021-01-09 13:44:55 +01:00
..
9p 9P: Cast to loff_t before multiplying 2020-11-05 11:43:34 +01:00
adfs Merge branch 'work.adfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 11:33:22 -07:00
affs affs: fix basic permission bits to actually work 2020-09-09 19:12:34 +02:00
afs afs: Fix memory leak when mounting with multiple source parameters 2020-12-30 11:50:54 +01:00
autofs autofs: fix a leak in autofs_expire_indirect() 2019-10-25 00:03:11 -04:00
befs fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
bfs bfs: don't use WARNING: string when it's just info. 2021-01-06 14:48:39 +01:00
btrfs btrfs: fix race when defragmenting leads to unnecessary IO 2021-01-06 14:48:36 +01:00
cachefiles cachefiles: Handle readpage error correctly 2020-11-05 11:43:36 +01:00
ceph ceph: fix race in concurrent __ceph_remove_cap invocations 2020-12-30 11:51:40 +01:00
cifs SMB3: avoid confusing warning message on mount to Azure 2020-12-30 11:51:40 +01:00
coda y2038: add inode timestamp clamping 2019-09-19 09:42:37 -07:00
configfs configfs: fix config_item refcnt leak in configfs_rmdir() 2020-05-27 17:46:30 +02:00
cramfs cramfs: fix usage on non-MTD device 2019-11-23 21:44:49 -05:00
crypto fscrypt: remove kernel-internal constants from UAPI header 2021-01-06 14:48:35 +01:00
debugfs debugfs: Fix module state check condition 2020-09-17 13:47:55 +02:00
devpts devpts_pty_kill(): don't bother with d_delete() 2019-09-03 09:30:56 -04:00
dlm fs: dlm: fix configfs memory leak 2020-10-29 09:58:03 +01:00
ecryptfs ecryptfs: replace BUG_ON with error handling code 2020-02-28 17:22:26 +01:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-12-02 08:49:53 +01:00
efs fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
erofs erofs: avoid using generic_block_bmap 2020-12-30 11:51:23 +01:00
exportfs exportfs_decode_fh(): negative pinned may become positive without the parent locked 2019-11-10 11:56:05 -05:00
ext2 ext2: don't update mtime on COW faults 2020-09-09 19:12:30 +02:00
ext4 ext4: don't remount read-only with errors=continue on reboot 2021-01-06 14:48:36 +01:00
f2fs f2fs: avoid race condition for shrinker count 2021-01-06 14:48:40 +01:00
fat fat: don't allow to mount if the FAT length == 0 2020-06-17 16:40:36 +02:00
freevxfs fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
fscache Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
fuse fuse: fix bad inode 2021-01-09 13:44:54 +01:00
gfs2 gfs2: check for empty rgrp tree in gfs2_ri_update 2020-12-11 13:23:32 +01:00
hfs treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
hfsplus hfsplus: fix crash and filesystem corruption when deleting files 2020-04-17 10:50:22 +02:00
hostfs This pull request contains the following changes for UML: 2019-05-12 17:52:13 -04:00
hpfs fs: hpfs: Initialize filesystem timestamp ranges 2019-08-30 08:11:25 -07:00
hugetlbfs hugetlbfs: prevent filesystem stacking of hugetlbfs 2020-09-03 11:26:48 +02:00
iomap iomap: fix WARN_ON_ONCE() from unprivileged users 2020-10-29 09:58:06 +01:00
isofs y2038: add inode timestamp clamping 2019-09-19 09:42:37 -07:00
jbd2 jbd2: fix up sparse warnings in checkpoint code 2020-11-18 19:20:30 +01:00
jffs2 jffs2: Fix NULL pointer dereference in rp_size fs option parsing 2021-01-06 14:48:37 +01:00
jfs jfs: Fix array index bounds check in dbAdjTree 2020-12-30 11:51:40 +01:00
kernfs kernfs: do not call fsnotify() with name without a parent 2020-08-19 08:16:12 +02:00
lockd lockd: don't use interval-based rebinding over TCP 2020-12-30 11:51:16 +01:00
minix fs/minix: remove expected error message in block_to_path() 2020-08-21 13:05:37 +02:00
nfs NFSv4: Fix a pNFS layout related use-after-free race when freeing the inode 2021-01-06 14:48:40 +01:00
nfs_common nfs_common: need lock during iterate through the list 2020-12-30 11:51:22 +01:00
nfsd nfsd: Fix message level for normal termination 2020-12-30 11:51:22 +01:00
nilfs2 nilfs2: fix null pointer dereference at nilfs_segctor_do_construct() 2020-06-17 16:40:29 +02:00
nls treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
notify fanotify: fix ignore mask logic for events on child and on dir 2020-06-17 16:40:24 +02:00
ntfs ntfs: add check for mft record size in superblock 2020-10-29 09:58:03 +01:00
ocfs2 ocfs2: initialize ip_next_orphan 2020-11-18 19:20:30 +01:00
omfs fs: omfs: Initialize filesystem timestamp ranges 2019-08-30 08:11:25 -07:00
openpromfs Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
orangefs orangefs: get rid of knob code... 2020-08-21 13:05:29 +02:00
overlayfs ovl: fix unneeded call to ovl_change_flags() 2020-07-22 09:33:12 +02:00
proc exec: Transform exec_update_mutex into a rw_semaphore 2021-01-09 13:44:55 +01:00
pstore pstore: Fix linking when crypto API disabled 2020-08-19 08:16:27 +02:00
qnx4 fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
qnx6 fs: Fill in max and min timestamps in superblock 2019-08-30 07:27:17 -07:00
quota quota: Don't overflow quota file offsets 2021-01-06 14:48:39 +01:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-29 09:57:53 +01:00
reiserfs reiserfs: add check for an invalid ih_entry_count 2021-01-06 14:48:38 +01:00
romfs romfs: fix uninitialized memory leak in romfs_dev_read() 2020-08-26 10:40:51 +02:00
squashfs Merge branch 'work.mount2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-09-19 10:06:57 -07:00
sysfs Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
sysv fs: sysv: Initialize filesystem timestamp ranges 2019-08-30 07:27:18 -07:00
tracefs tracing: Do not create tracefs files if tracefs lockdown is in effect 2019-10-12 20:49:07 -04:00
ubifs ubifs: prevent creating duplicate encrypted filenames 2021-01-06 14:48:35 +01:00
udf udf: Fix memory leak when mounting 2020-11-05 11:43:29 +01:00
ufs fs/ufs: avoid potential u32 multiplication overflow 2020-08-21 13:05:37 +02:00
unicode unicode: make array 'token' static const, makes object smaller 2019-09-17 11:48:24 -04:00
verity fs-verity: support builtin file signatures 2019-08-12 19:33:50 -07:00
xfs xfs: revert "xfs: fix rmap key and record comparison functions" 2020-11-24 13:29:18 +01:00
Kconfig fs-verity for 5.4 2019-09-18 16:59:14 -07:00
Kconfig.binfmt binfmt_flat: make support for old format binaries optional 2019-06-24 09:16:47 +10:00
Makefile fs-verity for 5.4 2019-09-18 16:59:14 -07:00
aio.c aio: fix async fsync creds 2020-06-17 16:40:24 +02:00
anon_inodes.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
attr.c utimes: Clamp the timestamps in notify_change() 2020-02-11 04:35:12 -08:00
bad_inode.c
…
binfmt_aout.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
binfmt_elf.c fs/binfmt_elf.c: allocate initialized memory in fill_thread_core_info() 2020-06-03 08:21:27 +02:00
binfmt_elf_fdpic.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
binfmt_em86.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-09-03 11:26:39 +02:00
binfmt_misc.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
binfmt_script.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
block_dev.c bdev: Reduce time holding bd_mutex in sync in blkdev_close() 2020-10-01 13:17:55 +02:00
buffer.c fs: Don't invalidate page buffers in block_write_full_page() 2020-11-05 11:43:24 +01:00
char_dev.c chardev: Avoid potential use-after-free in 'chrdev_open()' 2020-01-14 20:08:18 +01:00
compat.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
compat_binfmt_elf.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193 2019-05-30 11:29:21 -07:00
compat_ioctl.c fix compat handling of FICLONERANGE, FIDEDUPERANGE and FS_IOC_FIEMAP 2020-01-09 10:20:05 +01:00
coredump.c coredump: fix core_pattern parse error 2020-12-11 13:23:30 +01:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-29 09:57:45 +01:00
dax.c dax: pass NOWAIT flag to iomap_apply 2020-03-05 16:43:36 +01:00
dcache.c fix dget_parent() fastpath race 2020-10-01 13:17:19 +02:00
dcookies.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
direct-io.c fs/direct-io.c: fix kernel-doc warning 2019-10-14 15:04:01 -07:00
drop_caches.c fs: avoid softlockups in s_inodes iterators 2020-01-12 12:21:37 +01:00
eventfd.c eventfd: track eventfd_signal() recursion depth 2020-02-11 04:35:37 -08:00
eventpoll.c ep_create_wakeup_source(): dentry name can change under you... 2020-10-07 08:01:31 +02:00
exec.c exec: Transform exec_update_mutex into a rw_semaphore 2021-01-09 13:44:55 +01:00
fcntl.c fcntl: Fix potential deadlock in send_sig{io, urg}() 2021-01-06 14:48:39 +01:00
fhandle.c fs/handle.c - fix up kerneldoc 2019-08-07 21:51:47 -04:00
file.c fix multiplication overflow in copy_fdtable() 2020-05-27 17:46:12 +02:00
file_table.c vfs: Export flush_delayed_fput for use by knfsd. 2019-08-19 11:00:39 -04:00
filesystems.c fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() 2020-04-17 10:50:21 +02:00
fs-writeback.c writeback: Fix sync livelock due to b_dirty_time processing 2020-09-03 11:27:04 +02:00
fs_context.c vfs: subtype handling moved to fuse 2019-09-06 21:28:49 +02:00
fs_parser.c vfs: Make fs_parse() handle fs_param_is_fd-type params better 2019-09-12 21:06:14 -04:00
fs_pin.c switch the remnants of releasing the mountpoint away from fs_pin 2019-07-16 22:52:37 -04:00
fs_struct.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
fs_types.c
…
fsopen.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
inode.c futex: Fix inode life-time issue 2020-03-25 08:25:58 +01:00
internal.h fs: move guard_bio_eod() after bio_set_op_attrs 2020-01-17 19:48:21 +01:00
io_uring.c io_uring: Fix double list add in io_queue_async_work() 2020-10-14 10:32:57 +02:00
ioctl.c compat_ioctl: add compat_ptr_ioctl() 2019-12-17 19:55:30 +01:00
libfs.c libfs: fix error cast of negative value in simple_attr_write() 2020-11-24 13:29:19 +01:00
locks.c locks: reinstate locks_delete_block optimization 2020-03-25 08:25:41 +01:00
mbcache.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
mount.h switch the remnants of releasing the mountpoint away from fs_pin 2019-07-16 22:52:37 -04:00
mpage.c fs: move guard_bio_eod() after bio_set_op_attrs 2020-01-17 19:48:21 +01:00
namei.c namei: only return -ECHILD from follow_dotdot_rcu() 2020-03-05 16:43:48 +01:00
namespace.c fs/namespace.c: WARN if mnt_count has become negative 2021-01-06 14:48:40 +01:00
no-block.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
nsfs.c vfs: Convert nsfs to use the new mount API 2019-05-25 18:00:06 -04:00
open.c cifs_atomic_open(): fix double-put on late allocation failure 2020-03-18 07:17:51 +01:00
pipe.c vfs: Convert pipe to use the new mount API 2019-05-25 18:00:07 -04:00
pnode.c propagate_one(): mnt_set_mountpoint() needs mount_lock 2020-05-02 08:48:44 +02:00
pnode.h fs/namespace.c: WARN if mnt_count has become negative 2021-01-06 14:48:40 +01:00
posix_acl.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
proc_namespace.c vfs: subtype handling moved to fuse 2019-09-06 21:28:49 +02:00
read_write.c fs: allow deduplication of eof block into the end of the destination file 2020-02-11 04:35:23 -08:00
readdir.c readdir: be more conservative with directory entry names 2020-01-29 16:45:31 +01:00
select.c fs/select.c: use struct_size() in kmalloc() 2019-07-16 19:23:25 -07:00
seq_file.c seq_file: fix problem when seeking mid-record 2019-08-13 16:06:52 -07:00
signalfd.c fs/signalfd.c: fix inconsistent return codes for signalfd4 2020-08-26 10:40:58 +02:00
splice.c splice: only read in as much information as there is pipe buffer space 2019-12-17 19:56:52 +01:00
stack.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
stat.c
…
statfs.c vfs: Fix EOVERFLOW testing in put_compat_statfs64 2019-10-03 14:21:35 -07:00
super.c vfs: remove lockdep bogosity in __sb_start_write 2020-11-24 13:29:01 +01:00
sync.c fs/sync.c: sync_file_range(2) may use WB_SYNC_ALL writeback 2019-05-14 09:47:50 -07:00
timerfd.c timerfd: Prepare for PREEMPT_RT 2019-08-01 20:51:23 +02:00
userfaultfd.c userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK 2020-01-04 19:18:32 +01:00
utimes.c utimes: Clamp the timestamps in notify_change() 2020-02-11 04:35:12 -08:00
xattr.c xattr: break delegations in {set,remove}xattr 2020-08-11 15:33:39 +02:00