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Eric W. Biederman f7cfd871ae exec: Transform exec_update_mutex into a rw_semaphore
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>
2020-12-10 13:13:32 -06:00
..
9p Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
adfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
affs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
afs afs: Fix speculative status fetch going out of order wrt to modifications 2020-11-22 11:27:03 -08:00
autofs autofs: harden ioctl table 2020-10-16 11:11:22 -07:00
befs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
bfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
btrfs for-5.10-rc5-tag 2020-11-27 12:42:13 -08:00
cachefiles cachefiles: Handle readpage error correctly 2020-10-26 10:42:54 -07:00
ceph ceph: check session state after bumping session->s_seq 2020-11-04 20:55:49 +01:00
cifs cifs: fix potential use-after-free in cifs_echo_request() 2020-11-30 15:23:45 -06:00
coda docs: filesystems: convert coda.txt to ReST 2020-05-05 09:22:21 -06:00
configfs fs: configfs: delete repeated words in comments 2020-10-16 11:11:19 -07:00
cramfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
crypto fscrypt: fix inline encryption not used on new files 2020-11-11 20:59:07 -08:00
debugfs debugfs: remove return value of debugfs_create_devm_seqfile() 2020-10-30 08:37:39 +01:00
devpts
dlm networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
ecryptfs mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-11-25 16:55:02 +01:00
efs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
erofs erofs: fix setting up pcluster for temporary pages 2020-11-04 09:15:48 +08:00
exfat Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
exportfs
ext2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ext4 ext4: fix bogus warning in ext4_update_dx_flag() 2020-11-19 22:41:10 -05:00
f2fs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
fat [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
freevxfs
fscache Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-06-03 16:27:18 -07:00
fuse fuse update for 5.10 2020-10-19 14:28:30 -07:00
gfs2 gfs2: Fix deadlock between gfs2_{create_inode,inode_lookup} and delete_work_func 2020-12-01 00:21:10 +01:00
hfs fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
hfsplus fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
hostfs hostfs: Use kasprintf() instead of fixed buffer formatting 2020-03-29 23:23:00 +02:00
hpfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
hugetlbfs hugetlbfs: prevent filesystem stacking of hugetlbfs 2020-08-12 10:57:56 -07:00
iomap iomap: clean up writeback state logic on writepage error 2020-11-04 08:52:46 -08:00
isofs fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
jbd2 jbd2: fix kernel-doc markups 2020-11-19 22:38:29 -05:00
jffs2 treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
jfs fs: Introduce i_blocks_per_page 2020-09-21 08:59:26 -07:00
kernfs fsnotify: pass dir and inode arguments to fsnotify() 2020-07-27 23:15:48 +02:00
lockd The one new feature this time, from Anna Schumaker, is READ_PLUS, which 2020-10-22 09:44:27 -07:00
minix [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
nfs NFS: Remove unnecessary inode lock in nfs_fsync_dir() 2020-11-12 10:41:26 -05:00
nfs_common NFSv4.2: Fix NFS4ERR_STALE error when doing inter server copy 2020-10-21 10:31:20 -04:00
nfsd NFSD: fix missing refcount in nfsd4_copy by nfsd4_do_async_copy 2020-11-05 17:25:14 -05:00
nilfs2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
nls treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
notify fanotify: fix logic of reporting name info with watched parent 2020-11-09 15:03:08 +01:00
ntfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ocfs2 ocfs2: initialize ip_next_orphan 2020-11-14 11:26:04 -08:00
omfs fs: omfs: use kmemdup() rather than kmalloc+memcpy 2020-09-22 23:39:45 -04:00
openpromfs
orangefs orangefs: remove unnecessary assignment to variable ret 2020-08-04 15:01:58 -04:00
overlayfs ovl: use generic vfs_ioc_setflags_prepare() helper 2020-10-06 15:38:15 +02:00
proc exec: Transform exec_update_mutex into a rw_semaphore 2020-12-10 13:13:32 -06:00
pstore treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
qnx4 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
qnx6 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
quota \n 2020-10-15 14:56:15 -07:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-16 11:11:22 -07:00
reiserfs reiserfs: Fix oops during mount 2020-10-01 11:15:31 +02:00
romfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
squashfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-10-02 12:02:30 +02:00
sysv [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
tracefs
ubifs This pull request contains fixes for UBI and UBIFS 2020-10-18 09:56:50 -07:00
udf Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ufs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
unicode unicode: Add utf8_casefold_hash 2020-09-10 14:03:31 -07:00
vboxsf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2020-10-15 15:11:56 -07:00
verity fs-verity: use smp_load_acquire() for ->i_verity_info 2020-07-21 16:02:41 -07:00
xfs xfs: revert "xfs: fix rmap key and record comparison functions" 2020-11-19 15:17:50 -08:00
zonefs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
Kconfig tmpfs: support 64-bit inums per-sb 2020-08-07 11:33:24 -07:00
Kconfig.binfmt treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
aio.c vfs: separate __sb_start_write into blocking and non-blocking helpers 2020-11-10 16:53:07 -08:00
anon_inodes.c
attr.c
bad_inode.c fs: move the fiemap definitions out of fs.h 2020-06-03 23:16:55 -04:00
binfmt_aout.c exec: Rename flush_old_exec begin_new_exec 2020-05-07 16:55:47 -05:00
binfmt_elf.c fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
binfmt_elf_fdpic.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
binfmt_em86.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-08-24 08:49:13 +10:00
binfmt_misc.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_script.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
block_dev.c block: add a bdget_part helper 2020-10-05 10:38:33 -06:00
buffer.c mm, memcg: rework remote charging API to support nesting 2020-10-18 09:27:09 -07:00
char_dev.c vfs: allow unprivileged whiteout creation 2020-05-14 16:44:23 +02:00
compat_binfmt_elf.c Split the old READ_IMPLIES_EXEC workaround from executable PT_GNU_STACK 2020-06-05 13:45:21 -07:00
coredump.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-14 14:54:45 -07:00
dax.c fuse update for 5.10 2020-10-19 14:28:30 -07:00
dcache.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
dcookies.c
direct-io.c \n 2020-10-15 15:03:10 -07:00
drop_caches.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
eventfd.c eventfd: convert to f_op->read_iter() 2020-05-06 22:33:43 -04:00
eventpoll.c ep_create_wakeup_source(): dentry name can change under you... 2020-09-24 19:41:58 -04:00
exec.c exec: Transform exec_update_mutex into a rw_semaphore 2020-12-10 13:13:32 -06:00
fcntl.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fhandle.c
file.c io_uring: don't rely on weak ->files references 2020-09-30 20:32:32 -06:00
file_table.c task_work: cleanup notification modes 2020-10-17 15:05:30 -06:00
filesystems.c fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() 2020-04-10 15:36:22 -07:00
fs-writeback.c block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
fs_context.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fs_parser.c fs_parse: mark fs_param_bad_value() as static 2020-10-13 18:38:27 -07:00
fs_pin.c
fs_struct.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
fs_types.c
fsopen.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
init.c init: add an init_dup helper 2020-08-04 21:02:38 -04:00
inode.c fs: add a filesystem flag for THPs 2020-10-16 11:11:15 -07:00
internal.h fs: remove compat_sys_mount 2020-09-22 23:45:57 -04:00
io-wq.c io-wq: cancel request if it's asking for files and we don't have them 2020-11-04 10:22:56 -07:00
io-wq.h io_uring: unify fsize with def->work_flags 2020-10-20 16:03:13 -06:00
io_uring.c io_uring: fix files grab/cancel race 2020-11-26 08:50:21 -07:00
ioctl.c fs: remove ksys_ioctl 2020-07-31 08:16:01 +02:00
kernel_read_file.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
libfs.c libfs: fix error cast of negative value in simple_attr_write() 2020-11-22 10:48:22 -08:00
locks.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
mbcache.c
mount.h proc/mounts: add cursor 2020-05-14 16:44:24 +02:00
mpage.c fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
namei.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
namespace.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
no-block.c
nsfs.c nsproxy: attach to namespaces via pidfds 2020-05-13 11:41:22 +02:00
open.c exec: move S_ISREG() check earlier 2020-08-12 10:58:01 -07:00
pipe.c Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-11 11:11:35 -07:00
pnode.c propagate_one(): mnt_set_mountpoint() needs mount_lock 2020-04-27 10:37:14 -04:00
pnode.h
posix_acl.c vfs: clean up posix_acl_permission() logic aroudn MAY_NOT_BLOCK 2020-06-08 11:04:19 -07:00
proc_namespace.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
read_write.c Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
readdir.c fs: remove ksys_getdents64 2020-07-31 08:16:00 +02:00
remap_range.c vfs: move the remap range helpers to remap_range.c 2020-10-15 09:48:49 -07:00
select.c fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
seq_file.c seq_file: add seq_read_iter 2020-11-06 10:05:18 -08:00
signalfd.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
splice.c io_uring-5.10-2020-10-24 2020-10-24 12:40:18 -07:00
stack.c
stat.c fs: remove KSTAT_QUERY_FLAGS 2020-09-26 22:55:05 -04:00
statfs.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
super.c vfs: move __sb_{start,end}_write* to fs.h 2020-11-10 16:53:11 -08:00
sync.c overlayfs update for 5.8 2020-06-09 15:40:50 -07:00
timerfd.c
userfaultfd.c mm: remove the now-unnecessary mmget_still_valid() hack 2020-10-16 11:11:22 -07:00
utimes.c fs: expose utimes_common 2020-07-31 08:16:01 +02:00
xattr.c fs/xattr.c: fix kernel-doc warnings for setxattr & removexattr 2020-10-13 18:38:27 -07:00