linux_dsm_epyc7002/fs
Linus Torvalds 84c4e1f89f aio: simplify - and fix - fget/fput for io_submit()
Al Viro root-caused a race where the IOCB_CMD_POLL handling of
fget/fput() could cause us to access the file pointer after it had
already been freed:

 "In more details - normally IOCB_CMD_POLL handling looks so:

   1) io_submit(2) allocates aio_kiocb instance and passes it to
      aio_poll()

   2) aio_poll() resolves the descriptor to struct file by req->file =
      fget(iocb->aio_fildes)

   3) aio_poll() sets ->woken to false and raises ->ki_refcnt of that
      aio_kiocb to 2 (bumps by 1, that is).

   4) aio_poll() calls vfs_poll(). After sanity checks (basically,
      "poll_wait() had been called and only once") it locks the queue.
      That's what the extra reference to iocb had been for - we know we
      can safely access it.

   5) With queue locked, we check if ->woken has already been set to
      true (by aio_poll_wake()) and, if it had been, we unlock the
      queue, drop a reference to aio_kiocb and bugger off - at that
      point it's a responsibility to aio_poll_wake() and the stuff
      called/scheduled by it. That code will drop the reference to file
      in req->file, along with the other reference to our aio_kiocb.

   6) otherwise, we see whether we need to wait. If we do, we unlock the
      queue, drop one reference to aio_kiocb and go away - eventual
      wakeup (or cancel) will deal with the reference to file and with
      the other reference to aio_kiocb

   7) otherwise we remove ourselves from waitqueue (still under the
      queue lock), so that wakeup won't get us. No async activity will
      be happening, so we can safely drop req->file and iocb ourselves.

  If wakeup happens while we are in vfs_poll(), we are fine - aio_kiocb
  won't get freed under us, so we can do all the checks and locking
  safely. And we don't touch ->file if we detect that case.

  However, vfs_poll() most certainly *does* touch the file it had been
  given. So wakeup coming while we are still in ->poll() might end up
  doing fput() on that file. That case is not too rare, and usually we
  are saved by the still present reference from descriptor table - that
  fput() is not the final one.

  But if another thread closes that descriptor right after our fget()
  and wakeup does happen before ->poll() returns, we are in trouble -
  final fput() done while we are in the middle of a method:

Al also wrote a patch to take an extra reference to the file descriptor
to fix this, but I instead suggested we just streamline the whole file
pointer handling by submit_io() so that the generic aio submission code
simply keeps the file pointer around until the aio has completed.

Fixes: bfe4037e72 ("aio: implement IOCB_CMD_POLL")
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: syzbot+503d4cc169fcec1cb18c@syzkaller.appspotmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-04 10:32:48 -08:00
..
9p Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-11-01 19:58:52 -07:00
adfs adfs: use timespec64 for time conversion 2018-08-22 10:52:51 -07:00
affs affs: fix potential memory leak when parsing option 'prefix' 2018-05-28 12:36:41 +02:00
afs afs: Fix manually set volume location server list 2019-02-25 11:59:07 -08:00
autofs autofs: fix error return in autofs_fill_super() 2019-02-01 15:46:24 -08:00
befs fix a series of Documentation/ broken file name references 2018-06-15 18:10:01 -03:00
bfs bfs: extra sanity checking and static inode bitmap 2019-01-04 13:13:47 -08:00
btrfs for-5.0-rc4-tag 2019-02-03 08:48:33 -08:00
cachefiles fscache, cachefiles: remove redundant variable 'cache' 2018-11-30 16:00:58 +00:00
ceph ceph: avoid repeatedly adding inode to mdsc->snap_flush_list 2019-02-18 18:08:29 +01:00
cifs cifs: update internal module version number 2019-01-31 07:05:06 -06:00
coda vfs: change inode times to use struct timespec64 2018-06-05 16:57:31 -07:00
configfs configfs: fix registered group removal 2018-07-17 06:14:07 -07:00
cramfs Make the Cramfs code more robust against filesystem corruptions, 2018-10-30 12:46:25 -07:00
crypto fscrypt: add Adiantum support 2019-01-06 08:36:21 -05:00
debugfs debugfs: debugfs_lookup() should return NULL if not found 2019-01-30 12:39:49 +01:00
devpts devpts: Convert to new IDA API 2018-08-21 23:54:17 -04:00
dlm dlm: fix invalid cluster name warning 2018-12-03 15:30:24 -06:00
ecryptfs ecryptfs_rename(): verify that lower dentries are still OK after lock_rename() 2018-10-09 23:33:17 -04:00
efivarfs efivars: Call guid_parse() against guid_t type of variable 2018-07-22 14:13:44 +02:00
efs
exofs exofs_mount(): fix leaks on failure exits 2018-12-17 18:36:33 -05:00
exportfs exportfs: do not read dentry after free 2018-11-23 09:08:17 -05:00
ext2 \n 2018-12-27 17:00:35 -08:00
ext4 Revert "ext4: use ext4_write_inode() when fsyncing w/o a journal" 2019-01-31 23:41:11 -05:00
f2fs f2fs-for-4.21-rc1 2018-12-31 09:41:37 -08:00
fat Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
freevxfs freevxfs_lookup(): use d_splice_alias() 2018-05-22 14:27:51 -04:00
fscache fscache: fix race between enablement and dropping of object 2018-11-30 15:57:31 +00:00
fuse fuse: decrement NR_WRITEBACK_TEMP on the right page 2019-01-16 10:27:59 +01:00
gfs2 Revert "gfs2: read journal in large chunks to locate the head" 2019-02-14 09:52:51 -08:00
hfs hfs: do not free node before using 2018-11-30 14:56:14 -08:00
hfsplus hfsplus: return file attributes on statx 2019-01-04 13:13:47 -08:00
hostfs vfs: discard ATTR_ATTR_FLAG 2018-08-17 16:20:28 -07:00
hpfs hpfs: remove unnecessary checks on the value of r when assigning error code 2018-08-25 12:42:33 -07:00
hugetlbfs hugetlbfs: fix races and page leaks during migration 2019-03-01 09:02:33 -08:00
isofs Update email address 2018-09-29 22:47:48 -04:00
jbd2 jbd2: clean up indentation issue, replace spaces with tab 2018-12-04 00:20:10 -05:00
jffs2 jffs2: Fix use of uninitialized delayed_work, lockdep breakage 2018-12-02 09:20:34 +01:00
jfs jfs: remove redundant dquot_initialize() in jfs_evict_inode() 2018-09-20 09:28:49 -05:00
kernfs kernfs: Improve kernfs_notify() poll notification latency 2018-11-27 11:59:33 +01:00
lockd NFS client updates for Linux 4.21 2019-01-02 16:35:23 -08:00
minix minix_lookup: use d_splice_alias() 2018-05-22 14:27:52 -04:00
nfs Merge branch 'fixes-v5.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-02-20 09:09:33 -08:00
nfs_common
nfsd Revert "nfsd4: return default lease period" 2019-02-14 12:33:19 -05:00
nilfs2 nilfs2: Use xa_erase_irq 2018-11-05 14:57:05 -05:00
nls
notify inotify: Fix fd refcount leak in inotify_add_watch(). 2019-01-02 18:28:37 +01:00
ntfs mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
ocfs2 Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
omfs omfs_lookup(): report IO errors, use d_splice_alias() 2018-05-22 14:27:58 -04:00
openpromfs fs/openpromfs: Use of_node_name_eq for node name comparisons 2018-11-18 13:35:19 -08:00
orangefs orangefs: remove two un-needed BUG_ONs... 2019-02-20 15:12:52 -05:00
overlayfs Revert "ovl: relax permission checking on underlying layers" 2018-12-04 11:31:30 +01:00
proc proc, oom: do not report alien mms when setting oom_score_adj 2019-02-21 09:01:00 -08:00
pstore pstore/ram: Avoid allocation and leak of platform data 2019-01-20 14:44:52 -08:00
qnx4 qnx4_lookup: use d_splice_alias() 2018-05-22 14:27:52 -04:00
qnx6 qnx6_lookup: switch to d_splice_alias() 2018-05-22 14:27:54 -04:00
quota quota: Lock s_umount in exclusive mode for Q_XQUOTA{ON,OFF} quotactls. 2018-12-18 18:29:15 +01:00
ramfs
reiserfs reiserfs: remove workaround code for GCC 3.x 2018-10-31 08:54:14 -07:00
romfs romfs_lookup: switch to d_splice_alias() 2018-05-22 14:27:55 -04:00
squashfs Squashfs: Compute expected length from inode size rather than block length 2018-08-02 09:34:02 -07:00
sysfs sysfs: convert BUG_ON to WARN_ON 2019-01-07 08:53:32 +01:00
sysv sysv: return 'err' instead of 0 in __sysv_write_inode 2018-11-10 08:02:40 -05:00
tracefs tracefs: Annotate tracefs_ops with __ro_after_init 2018-07-31 11:32:44 -04:00
ubifs mm: migrate: drop unused argument of migrate_page_move_mapping() 2018-12-28 12:11:51 -08:00
udf \n 2018-12-27 17:00:35 -08:00
ufs fs/ufs: use ktime_get_real_seconds for sb and cg timestamps 2018-08-17 16:20:27 -07:00
xfs xfs: set buffer ops when repair probes for btree type 2019-02-03 14:03:59 -08:00
aio.c aio: simplify - and fix - fget/fput for io_submit() 2019-03-04 10:32:48 -08:00
anon_inodes.c anon_inode_getfile(): switch to alloc_file_pseudo() 2018-07-12 10:04:27 -04:00
attr.c fs: Fix attr.c kernel-doc 2018-07-03 16:44:45 -04:00
bad_inode.c get rid of 'opened' argument of ->atomic_open() - part 3 2018-07-12 10:04:20 -04:00
binfmt_aout.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
binfmt_elf_fdpic.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
binfmt_elf.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c turn filp_clone_open() into inline wrapper for dentry_open() 2018-07-10 23:29:03 -04:00
binfmt_script.c exec: load_script: Do not exec truncated interpreter path 2019-02-18 16:49:36 -08:00
block_dev.c blockdev: Fix livelocks on loop device 2019-01-15 07:30:56 -07:00
buffer.c fs: ratelimit __find_get_block_slow() failure message. 2019-02-06 12:58:56 -07:00
char_dev.c
compat_binfmt_elf.c y2038: globally rename compat_time to old_time32 2018-08-27 14:48:48 +02:00
compat_ioctl.c media updates for v4.20-rc1 2018-10-29 14:29:58 -07:00
compat.c ncpfs: remove compat functionality 2018-06-05 19:23:26 +02:00
coredump.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
d_path.c
dax.c dax fix 4.21 2018-12-31 09:46:39 -08:00
dcache.c fs/dcache: Track & report number of negative dentries 2019-01-30 11:02:11 -08:00
dcookies.c
direct-io.c direct-io: allow direct writes to empty inodes 2019-01-22 08:26:44 -07:00
drop_caches.c fs/drop_caches.c: avoid softlockups in drop_pagecache_sb() 2019-02-01 15:46:24 -08:00
eventfd.c Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
eventpoll.c Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
exec.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:18:59 -08:00
fcntl.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
fhandle.c
file_table.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
file.c Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -08:00
filesystems.c
fs_pin.c
fs_struct.c
fs-writeback.c writeback: synchronize sync(2) against cgroup writeback membership switches 2019-01-22 14:39:38 -07:00
inode.c Revert "mm: don't reclaim inodes with many attached pages" 2019-02-12 16:33:18 -08:00
internal.h overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
ioctl.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
iomap.c iomap: fix a use after free in iomap_dio_rw 2019-01-27 08:47:42 -08:00
Kconfig autofs: remove left-over autofs4 stubs 2018-06-11 08:22:34 -07:00
Kconfig.binfmt kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
libfs.c
locks.c locks: fix error in locks_move_blocks() 2019-01-02 20:14:50 -05:00
Makefile autofs: remove left-over autofs4 stubs 2018-06-11 08:22:34 -07:00
mbcache.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
mount.h
mpage.c mpage: mpage_readpages() should submit IO as read-ahead 2018-08-17 16:20:29 -07:00
namei.c Revert "vfs: Allow userns root to call mknod on owned filesystems." 2018-12-22 14:18:34 -08:00
namespace.c Revert "x86/fault: BUG() when uaccess helpers fault on kernel addresses" 2019-02-25 09:10:51 -08:00
no-block.c
nsfs.c
open.c overlayfs update for 4.19 2018-08-21 18:19:09 -07:00
pipe.c Merge branch 'work.open3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-08-13 19:58:36 -07:00
pnode.c vfs: Suppress MS_* flag defs within the kernel unless explicitly enabled 2018-12-20 16:32:56 +00:00
pnode.h
posix_acl.c
proc_namespace.c
read_write.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
readdir.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
select.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
seq_file.c fs/seq_file.c: simplify seq_file iteration code and interface 2018-08-17 16:20:28 -07:00
signalfd.c signal: Distinguish between kernel_siginfo and siginfo 2018-10-03 16:47:43 +02:00
splice.c splice: don't read more than available pipe space 2018-12-04 08:50:49 -08:00
stack.c
stat.c y2038: Remove newstat family from default syscall set 2018-08-29 15:42:20 +02:00
statfs.c kernel: add kcompat_sys_{f,}statfs64() 2018-07-12 14:49:48 +01:00
super.c mount_fs: suppress MAC on MS_SUBMOUNT as well as MS_KERNMOUNT 2018-12-21 11:51:23 -05:00
sync.c
timerfd.c y2038: globally rename compat_time to old_time32 2018-08-27 14:48:48 +02:00
userfaultfd.c userfaultfd: clear flag if remap event not enabled 2018-12-28 12:11:51 -08:00
utimes.c y2038: utimes: Rework #ifdef guards for compat syscalls 2018-08-29 15:42:23 +02:00
xattr.c sysfs: Do not return POSIX ACL xattrs via listxattr 2018-09-18 07:30:48 -04:00