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kernel_optimize_test/fs
History
Linus Torvalds 4baba6ba56 fget: check that the fd still exists after getting a ref to it 
commit 054aa8d439b9185d4f5eb9a90282d1ce74772969 upstream.

Jann Horn points out that there is another possible race wrt Unix domain
socket garbage collection, somewhat reminiscent of the one fixed in
commit cbcf01128d0a ("af_unix: fix garbage collect vs MSG_PEEK").

See the extended comment about the garbage collection requirements added
to unix_peek_fds() by that commit for details.

The race comes from how we can locklessly look up a file descriptor just
as it is in the process of being closed, and with the right artificial
timing (Jann added a few strategic 'mdelay(500)' calls to do that), the
Unix domain socket garbage collector could see the reference count
decrement of the close() happen before fget() took its reference to the
file and the file was attached onto a new file descriptor.

This is all (intentionally) correct on the 'struct file *' side, with
RCU lookups and lockless reference counting very much part of the
design.  Getting that reference count out of order isn't a problem per
se.

But the garbage collector can get confused by seeing this situation of
having seen a file not having any remaining external references and then
seeing it being attached to an fd.

In commit cbcf01128d0a ("af_unix: fix garbage collect vs MSG_PEEK") the
fix was to serialize the file descriptor install with the garbage
collector by taking and releasing the unix_gc_lock.

That's not really an option here, but since this all happens when we are
in the process of looking up a file descriptor, we can instead simply
just re-check that the file hasn't been closed in the meantime, and just
re-do the lookup if we raced with a concurrent close() of the same file
descriptor.

Reported-and-tested-by: Jann Horn <jannh@google.com>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-12-08 09:03:21 +01:00
..
9p new helper: inode_wrong_type() 2021-09-08 08:49:01 +02:00
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 fs/affs: release old buffer head on error path 2021-03-04 11:38:37 +01:00
afs afs: Fix updating of i_blocks on file/dir extension 2021-09-30 10:11:01 +02:00
autofs
befs
bfs bfs: don't use WARNING: string when it's just info. 2021-01-06 14:56:52 +01:00
btrfs btrfs: check-integrity: fix a warning on write caching disabled disk 2021-12-08 09:03:19 +01:00
cachefiles fs/cachefiles: Remove wait_bit_key layout dependency 2021-03-30 14:32:07 +02:00
ceph ceph: properly handle statfs on multifs setups 2021-12-01 09:19:08 +01:00
cifs smb3: do not error on fsync when readonly 2021-12-01 09:19:08 +01:00
coda
configfs configfs: fix memleak in configfs_release_bin_file 2021-07-14 16:56:48 +02:00
cramfs
crypto fscrypt: allow 256-bit master keys with AES-256-XTS 2021-11-18 14:03:54 +01:00
debugfs debugfs: debugfs_create_file_size(): use IS_ERR to check for error 2021-10-06 15:55:59 +02:00
devpts
dlm fs: dlm: fix memory leak when fenced 2021-07-14 16:55:59 +02:00
ecryptfs Revert "ecryptfs: replace BUG_ON with error handling code" 2021-05-26 12:06:55 +02:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-11-25 16:55:02 +01:00
efs
erofs erofs: fix deadlock when shrink erofs slab 2021-12-01 09:19:05 +01:00
exfat exfat: fix incorrect loading of i_blocks for large files 2021-11-18 14:03:37 +01:00
exportfs
ext2 ext2: fix sleeping in atomic bugs on error 2021-10-09 14:40:56 +02:00
ext4 ext4: refresh the ext4_ext_path struct after dropping i_data_sem. 2021-11-18 14:03:40 +01:00
f2fs f2fs: set SBI_NEED_FSCK flag when inconsistent node block found 2021-12-01 09:19:08 +01:00
fat
freevxfs
fscache fscache: Fix cookie key hashing 2021-09-18 13:40:15 +02:00
fuse fuse: release pipe buf after last use 2021-12-01 09:19:00 +01:00
gfs2 gfs2: Fix length of holes reported at end-of-file 2021-12-08 09:03:18 +01:00
hfs hfs: add lock nesting notation to hfs_find_init 2021-07-31 08:16:12 +02:00
hfsplus hfsplus: prevent corruption in shrinking truncate 2021-05-19 10:13:10 +02:00
hostfs hostfs: fix memory handling in follow_link() 2021-04-14 08:42:06 +02:00
hpfs
hugetlbfs hugetlbfs: fix mount mode command line processing 2021-07-28 14:35:46 +02:00
iomap treewide: Change list_sort to use const pointers 2021-09-30 10:11:04 +02:00
isofs isofs: Fix out of bound access for corrupted isofs image 2021-11-12 14:58:33 +01:00
jbd2 ext4: fix debug format string warning 2021-05-19 10:13:19 +02:00
jffs2 jffs2: check the validity of dstlen in jffs2_zlib_compress() 2021-05-11 14:47:36 +02:00
jfs JFS: fix memleak in jfs_mount 2021-11-18 14:04:15 +01:00
kernfs kernfs: wire up ->splice_read and ->splice_write 2021-01-27 11:55:29 +01:00
lockd lockd: lockd server-side shouldn't set fl_ops 2021-09-18 13:40:30 +02:00
minix
nfs NFSv42: Fix pagecache invalidation after COPY/CLONE 2021-12-08 09:03:17 +01:00
nfs_common nfs_common: need lock during iterate through the list 2020-12-30 11:53:45 +01:00
nfsd NFSD: Keep existing listeners on portlist error 2021-10-27 09:56:47 +02:00
nilfs2 nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group 2021-09-26 14:09:01 +02:00
nls
notify fanotify: limit number of event merge attempts 2021-09-18 13:40:38 +02:00
ntfs ntfs: fix validity check for file name attribute 2021-07-14 16:55:38 +02:00
ocfs2 ocfs2: fix data corruption on truncate 2021-11-18 14:03:37 +01:00
omfs
openpromfs
orangefs fs: orangefs: fix error return code of orangefs_revalidate_lookup() 2021-11-18 14:04:23 +01:00
overlayfs ovl: fix deadlock in splice write 2021-12-08 09:03:18 +01:00
proc proc/vmcore: fix clearing user buffer by properly using clear_user() 2021-12-01 09:19:02 +01:00
pstore mark pstore-blk as broken 2021-07-14 16:56:12 +02:00
qnx4 qnx4: work around gcc false positive warning bug 2021-09-30 10:11:08 +02:00
qnx6
quota quota: correct error number in free_dqentry() 2021-11-18 14:03:51 +01:00
ramfs
reiserfs reiserfs: check directory items on read from disk 2021-08-12 13:22:19 +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 squashfs: fix divide error in calculate_skip() 2021-05-19 10:13:10 +02:00
sysfs
sysv
tracefs tracefs: Have tracefs directories not set OTH permission bits by default 2021-11-18 14:03:56 +01:00
ubifs treewide: Change list_sort to use const pointers 2021-09-30 10:11:04 +02:00
udf udf: Fix crash after seekdir 2021-11-26 10:39:20 +01:00
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
vboxsf vboxfs: fix broken legacy mount signature checking 2021-10-17 10:43:33 +02:00
verity fs-verity: fix signed integer overflow with i_size near S64_MAX 2021-10-06 15:55:46 +02:00
xfs treewide: Change list_sort to use const pointers 2021-09-30 10:11:04 +02:00
zonefs zonefs: fix to update .i_wr_refcnt correctly in zonefs_open_zone() 2021-03-25 09:04:05 +01:00
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
binfmt_aout.c
binfmt_elf_fdpic.c
binfmt_elf.c elf: don't use MAP_FIXED_NOREPLACE for elf interpreter mappings 2021-10-06 15:55:59 +02:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c binfmt_misc: fix possible deadlock in bm_register_write 2021-03-17 17:06:35 +01:00
binfmt_script.c
block_dev.c block: fix a race between del_gendisk and BLKRRPART 2021-06-03 09:00:45 +02:00
buffer.c
char_dev.c
compat_binfmt_elf.c
coredump.c coredump: fix memleak in dump_vma_snapshot() 2021-09-26 14:08:56 +02:00
d_path.c
dax.c dax: fix ENOMEM handling in grab_mapping_entry() 2021-07-14 16:56:13 +02:00
dcache.c
dcookies.c
direct-io.c fs: direct-io: fix missing sdio->boundary 2021-04-14 08:41:58 +02:00
drop_caches.c
eventfd.c
eventpoll.c fs/epoll: restore waking from ep_done_scan() 2021-05-11 14:47:12 +02:00
exec.c Revert "Add a reference to ucounts for each cred" 2021-09-08 08:49:00 +02:00
fcntl.c fcntl: fix potential deadlock for &fasync_struct.fa_lock 2021-09-15 09:50:27 +02:00
fhandle.c
file_table.c
file.c fget: check that the fd still exists after getting a ref to it 2021-12-08 09:03:21 +01:00
filesystems.c
fs_context.c
fs_parser.c
fs_pin.c
fs_struct.c
fs_types.c
fs-writeback.c writeback: fix obtain a reference to a freeing memcg css 2021-07-14 16:56:31 +02:00
fsopen.c
init.c
inode.c fs: export an inode_update_time helper 2021-11-26 10:39:22 +01:00
internal.h cgroup1: fix leaked context root causing sporadic NULL deref in LTP 2021-07-31 08:16:11 +02:00
io_uring.c Revert "io_uring: reinforce cancel on flush during exit" 2021-11-06 14:10:08 +01:00
io-wq.c io-wq: fix wakeup race when adding new work 2021-09-18 13:40:06 +02:00
io-wq.h io_uring: always batch cancel in *cancel_files() 2021-02-13 13:54:56 +01:00
ioctl.c
Kconfig tmpfs: disallow CONFIG_TMPFS_INODE64 on alpha 2021-02-17 11:02:21 +01:00
Kconfig.binfmt
kernel_read_file.c vfs: check fd has read access in kernel_read_file_from_fd() 2021-10-27 09:56:51 +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 Revert "nfsd4: a client's own opens needn't prevent delegations" 2021-03-20 10:43:44 +01:00
Makefile Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
mbcache.c
mount.h
mpage.c
namei.c LOOKUP_MOUNTPOINT: we are cleaning "jumped" flag too late 2021-04-14 08:41:58 +02:00
namespace.c fs: warn about impending deprecation of mandatory locks 2021-08-26 08:35:57 -04:00
no-block.c
nsfs.c
open.c open: don't silently ignore unknown O-flags in openat2() 2021-07-14 16:55:59 +02:00
pipe.c pipe: do FASYNC notifications for every pipe IO, not just state changes 2021-09-03 10:09:28 +02:00
pnode.c
pnode.h mount: fix mounting of detached mounts onto targets that reside on shared mounts 2021-03-17 17:06:13 +01:00
posix_acl.c
proc_namespace.c proc mountinfo: make splice available again 2020-12-30 11:54:02 +01:00
read_write.c Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
readdir.c readdir: make sure to verify directory entry for legacy interfaces too 2021-04-21 13:00:54 +02:00
remap_range.c
select.c kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data() 2021-03-25 09:04:16 +01:00
seq_file.c seq_file: disallow extremely large seq buffer allocations 2021-07-20 16:05:59 +02:00
signalfd.c
splice.c io_uring-5.10-2020-10-24 2020-10-24 12:40:18 -07:00
stack.c
stat.c fs: fix reporting supported extra file attributes for statx() 2021-05-11 14:47:33 +02:00
statfs.c
super.c vfs: move __sb_{start,end}_write* to fs.h 2020-11-10 16:53:11 -08:00
sync.c
timerfd.c
userfaultfd.c userfaultfd: fix a race between writeprotect and exit_mmap() 2021-10-27 09:56:51 +02:00
utimes.c
xattr.c