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Luis Chamberlain ff6c472175 coredump: fix crash when umh is disabled 
commit 3740d93e37902b31159a82da2d5c8812ed825404 upstream.

Commit 64e90a8acb859 ("Introduce STATIC_USERMODEHELPER to mediate
call_usermodehelper()") added the optiont to disable all
call_usermodehelper() calls by setting STATIC_USERMODEHELPER_PATH to
an empty string. When this is done, and crashdump is triggered, it
will crash on null pointer dereference, since we make assumptions
over what call_usermodehelper_exec() did.

This has been reported by Sergey when one triggers a a coredump
with the following configuration:

```
CONFIG_STATIC_USERMODEHELPER=y
CONFIG_STATIC_USERMODEHELPER_PATH=""
kernel.core_pattern = |/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %e
```

The way disabling the umh was designed was that call_usermodehelper_exec()
would just return early, without an error. But coredump assumes
certain variables are set up for us when this happens, and calls
ile_start_write(cprm.file) with a NULL file.

[    2.819676] BUG: kernel NULL pointer dereference, address: 0000000000000020
[    2.819859] #PF: supervisor read access in kernel mode
[    2.820035] #PF: error_code(0x0000) - not-present page
[    2.820188] PGD 0 P4D 0
[    2.820305] Oops: 0000 [#1] SMP PTI
[    2.820436] CPU: 2 PID: 89 Comm: a Not tainted 5.7.0-rc1+ #7
[    2.820680] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190711_202441-buildvm-armv7-10.arm.fedoraproject.org-2.fc31 04/01/2014
[    2.821150] RIP: 0010:do_coredump+0xd80/0x1060
[    2.821385] Code: e8 95 11 ed ff 48 c7 c6 cc a7 b4 81 48 8d bd 28 ff
ff ff 89 c2 e8 70 f1 ff ff 41 89 c2 85 c0 0f 84 72 f7 ff ff e9 b4 fe ff
ff <48> 8b 57 20 0f b7 02 66 25 00 f0 66 3d 00 8
0 0f 84 9c 01 00 00 44
[    2.822014] RSP: 0000:ffffc9000029bcb8 EFLAGS: 00010246
[    2.822339] RAX: 0000000000000000 RBX: ffff88803f860000 RCX: 000000000000000a
[    2.822746] RDX: 0000000000000009 RSI: 0000000000000282 RDI: 0000000000000000
[    2.823141] RBP: ffffc9000029bde8 R08: 0000000000000000 R09: ffffc9000029bc00
[    2.823508] R10: 0000000000000001 R11: ffff88803dec90be R12: ffffffff81c39da0
[    2.823902] R13: ffff88803de84400 R14: 0000000000000000 R15: 0000000000000000
[    2.824285] FS:  00007fee08183540(0000) GS:ffff88803e480000(0000) knlGS:0000000000000000
[    2.824767] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    2.825111] CR2: 0000000000000020 CR3: 000000003f856005 CR4: 0000000000060ea0
[    2.825479] Call Trace:
[    2.825790]  get_signal+0x11e/0x720
[    2.826087]  do_signal+0x1d/0x670
[    2.826361]  ? force_sig_info_to_task+0xc1/0xf0
[    2.826691]  ? force_sig_fault+0x3c/0x40
[    2.826996]  ? do_trap+0xc9/0x100
[    2.827179]  exit_to_usermode_loop+0x49/0x90
[    2.827359]  prepare_exit_to_usermode+0x77/0xb0
[    2.827559]  ? invalid_op+0xa/0x30
[    2.827747]  ret_from_intr+0x20/0x20
[    2.827921] RIP: 0033:0x55e2c76d2129
[    2.828107] Code: 2d ff ff ff e8 68 ff ff ff 5d c6 05 18 2f 00 00 01
c3 0f 1f 80 00 00 00 00 c3 0f 1f 80 00 00 00 00 e9 7b ff ff ff 55 48 89
e5 <0f> 0b b8 00 00 00 00 5d c3 66 2e 0f 1f 84 0
0 00 00 00 00 0f 1f 40
[    2.828603] RSP: 002b:00007fffeba5e080 EFLAGS: 00010246
[    2.828801] RAX: 000055e2c76d2125 RBX: 0000000000000000 RCX: 00007fee0817c718
[    2.829034] RDX: 00007fffeba5e188 RSI: 00007fffeba5e178 RDI: 0000000000000001
[    2.829257] RBP: 00007fffeba5e080 R08: 0000000000000000 R09: 00007fee08193c00
[    2.829482] R10: 0000000000000009 R11: 0000000000000000 R12: 000055e2c76d2040
[    2.829727] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[    2.829964] CR2: 0000000000000020
[    2.830149] ---[ end trace ceed83d8c68a1bf1 ]---
```

Cc: <stable@vger.kernel.org> # v4.11+
Fixes: 64e90a8acb85 ("Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper()")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199795
Reported-by: Tony Vroon <chainsaw@gentoo.org>
Reported-by: Sergey Kvachonok <ravenexp@gmail.com>
Tested-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20200416162859.26518-1-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-20 08:16:58 +02:00
..
9p
9p: avoid attaching writeback_fid on mmap with type PRIVATE
2019-10-11 18:18:38 +02:00
adfs
fs/adfs: super: fix use-after-free bug
2019-08-06 19:05:21 +02:00
affs
affs: fix a memory leak in affs_remount
2020-01-27 14:46:52 +01:00
afs
afs: Fix some tracing details
2020-04-02 16:34:33 +02:00
autofs4
autofs: fix a leak in autofs_expire_indirect()
2019-12-17 20:37:24 +01:00
befs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
bfs
bfs: add sanity check at bfs_fill_super()
2018-12-01 09:42:51 +01:00
btrfs
btrfs: fix partial loss of prealloc extent past i_size after fsync
2020-05-05 19:15:49 +02:00
cachefiles
fscache, cachefiles: remove redundant variable 'cache'
2018-12-17 09:28:53 +01:00
ceph
ceph: don't skip updating wanted caps when cap is stale
2020-05-02 17:24:13 +02:00
cifs
cifs: protect updating server->dstaddr with a spinlock
2020-05-10 10:29:00 +02:00
coda
coda: add error handling for fget
2019-08-06 19:05:23 +02:00
configfs
configfs: fix a deadlock in configfs_symlink()
2019-11-12 19:18:18 +01:00
cramfs
Cramfs: fix abad comparison when wrap-arounds occur
2018-11-13 11:15:12 -08:00
crypto
fscrypt: clean up some BUG_ON()s in block encryption/decryption
2019-07-31 07:28:22 +02:00
debugfs
debugfs: fix use-after-free on symlink traversal
2019-05-08 07:20:49 +02:00
devpts
fs/devpts: always delete dcache dentry-s in dput()
2019-03-23 14:35:21 +01:00
dlm
dlm: fix invalid cluster name warning
2019-12-17 20:38:33 +01:00
ecryptfs
ecryptfs: Fix up bad backport of fe2e082f5da5b4a0a92ae32978f81507ef37ec66
2020-03-11 18:02:51 +01:00
efivarfs
VFS: Kill off s_options and helpers
2017-07-11 06:09:21 -04:00
efs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
exofs
exofs_mount(): fix leaks on failure exits
2019-12-05 15:37:28 +01:00
exportfs
exportfs: fix 'passing zero to ERR_PTR()' warning
2020-01-27 14:46:06 +01:00
ext2
ext2: fix debug reference to ext2_xattr_cache
2020-04-24 08:01:22 +02:00
ext4
ext4: fix special inode number checks in __ext4_iget()
2020-05-05 19:15:47 +02:00
f2fs
f2fs: fix memleak of kobject
2020-02-28 16:36:05 +01:00
fat
fat: fix uninit-memory access for partial initialized inode
2020-03-11 18:03:03 +01:00
freevxfs
…
fscache
fscache: fix race between enablement and dropping of object
2018-12-17 09:28:53 +01:00
fuse
fuse: verify attributes
2019-12-17 20:38:44 +01:00
gfs2
gfs2: Don't demote a glock until its revokes are written
2020-04-24 08:00:27 +02:00
hfs
fs/hfs/extent.c: fix array out of bounds read of array extent
2019-12-01 09:13:57 +01:00
hfsplus
hfsplus: fix crash and filesystem corruption when deleting files
2020-04-24 08:00:45 +02:00
hostfs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
hpfs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
hugetlbfs
hugetlb: use same fault hash key for shared and private mappings
2019-05-31 06:47:12 -07:00
isofs
isofs: reject hardware sector size > 2048 bytes
2018-10-03 17:00:57 -07:00
jbd2
jbd2: improve comments about freeing data buffers whose page mapping is NULL
2020-04-24 08:00:54 +02:00
jffs2
jffs2: fix use-after-free on symlink traversal
2019-05-08 07:20:49 +02:00
jfs
jfs: fix bogus variable self-initialization
2020-01-27 14:46:26 +01:00
kernfs
kernfs: fix ino wrap-around detection
2019-12-17 20:38:50 +01:00
lockd
lockd: fix decoding of TEST results
2019-12-17 20:38:15 +01:00
minix
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
ncpfs
staging: ncpfs: memory corruption in ncp_read_kernel()
2018-03-28 18:24:43 +02:00
nfs
nfs: Fix potential posix_acl refcnt leak in nfs3_set_acl
2020-05-05 19:15:52 +02:00
nfs_common
lockd: fix "list_add double add" caused by legacy signal interface
2018-02-03 17:39:08 +01:00
nfsd
nfsd: memory corruption in nfsd4_lock()
2020-05-02 17:24:41 +02:00
nilfs2
do d_instantiate/unlock_new_inode combinations safely
2018-05-30 07:51:47 +02:00
nls
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
notify
fs: avoid softlockups in s_inodes iterators
2020-01-12 12:11:59 +01:00
ntfs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
ocfs2
ocfs2: no need try to truncate file beyond i_size
2020-04-24 08:00:43 +02:00
omfs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
openpromfs
…
orangefs
help_next should increase position index
2020-02-28 16:36:08 +01:00
overlayfs
ovl: relax WARN_ON() on rename to self
2019-12-17 20:39:21 +01:00
proc
vmalloc: fix remap_vmalloc_range() bounds checks
2020-05-02 17:24:21 +02:00
pstore
pstore/ram: Write new dumps to start of recycled zones
2020-01-09 10:17:55 +01:00
qnx4
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
qnx6
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
quota
fs: avoid softlockups in s_inodes iterators
2020-01-12 12:11:59 +01:00
ramfs
mm: make pagevec_lookup() update index
2017-09-06 17:27:26 -07:00
reiserfs
reiserfs: prevent NULL pointer dereference in reiserfs_insert_item()
2020-02-28 16:36:08 +01:00
romfs
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
squashfs
Squashfs: Compute expected length from inode size rather than block length
2018-09-05 09:26:32 +02:00
sysfs
scsi: sysfs: Introduce sysfs_{un,}break_active_protection()
2018-09-05 09:26:41 +02:00
sysv
sysv: return 'err' instead of 0 in __sysv_write_inode
2018-12-17 09:28:48 +01:00
tracefs
VFS: Don't use save/replace_mount_options if not using generic_show_options
2017-07-06 03:31:46 -04:00
ubifs
ubifs: don't trigger assertion on invalid no-key filename
2020-02-14 16:32:11 -05:00
udf
udf: Fix free space reporting for metadata and virtual partitions
2020-02-28 16:36:02 +01:00
ufs
ufs: fix braino in ufs_get_inode_gid() for solaris UFS flavour
2019-05-25 18:25:36 +02:00
xfs
xfs: fix partially uninitialized structure in xfs_reflink_remap_extent
2020-05-02 17:24:43 +02:00
aio.c
aio: fix spectre gadget in lookup_ioctx
2018-12-21 14:13:04 +01:00
anon_inodes.c
…
attr.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
bad_inode.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
binfmt_aout.c
fs: fix kernel_read prototype
2017-09-04 19:05:15 -04:00
binfmt_elf_fdpic.c
Merge branch 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2017-09-14 18:13:32 -07:00
binfmt_elf.c
binfmt_elf: Do not move brk for INTERP-less ET_EXEC
2019-10-05 12:48:06 +02:00
binfmt_em86.c
…
binfmt_flat.c
fs/binfmt_flat.c: make load_flat_shared_library() work
2019-07-03 13:15:59 +02:00
binfmt_misc.c
fs/binfmt_misc.c: do not allow offset overflow
2018-06-26 08:06:33 +08:00
binfmt_script.c
exec: load_script: Do not exec truncated interpreter path
2019-11-06 12:42:59 +01:00
block_dev.c
block: fix the return errno for direct IO
2019-04-17 08:37:53 +02:00
buffer.c
ext4: use non-movable memory for superblock readahead
2020-04-24 08:01:00 +02:00
char_dev.c
chardev: Avoid potential use-after-free in 'chrdev_open()'
2020-01-14 20:05:39 +01:00
compat_binfmt_elf.c
…
compat_ioctl.c
fix compat handling of FICLONERANGE, FIDEDUPERANGE and FS_IOC_FIEMAP
2020-01-09 10:17:58 +01:00
compat.c
…
coredump.c
coredump: fix crash when umh is disabled
2020-05-20 08:16:58 +02:00
dax.c
dax: pass NOWAIT flag to iomap_apply
2020-03-11 18:02:43 +01:00
dcache.c
fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache_sb()
2019-02-06 17:31:34 +01:00
dcookies.c
…
direct-io.c
iomap: report collisions between directio and buffered writes to userspace
2019-04-27 09:35:41 +02:00
drop_caches.c
fs: avoid softlockups in s_inodes iterators
2020-01-12 12:11:59 +01:00
eventfd.c
There has been a fair amount of activity in the docs tree this time
2017-07-03 21:13:25 -07:00
eventpoll.c
fs/epoll: drop ovflist branch prediction
2019-02-12 19:46:10 +01:00
exec.c
signal: Extend exec_id to 64bits
2020-04-24 08:00:38 +02:00
fcntl.c
fcntl: don't cap l_start and l_end values for F_GETLK64 in compat syscall
2017-12-17 15:07:59 +01:00
fhandle.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
file_table.c
fput: Don't reinvent the wheel but use existing llist API
2017-08-28 00:50:23 -04:00
file.c
fs/file.c: initialize init_files.resize_wait
2019-04-05 22:31:28 +02:00
filesystems.c
fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once()
2020-04-24 08:00:43 +02:00
fs_pin.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
fs_struct.c
…
fs-writeback.c
cgroup,writeback: don't switch wbs immediately on dead wbs if the memcg is dead
2019-11-12 19:18:47 +01:00
inode.c
futex: Fix inode life-time issue
2020-04-02 16:34:21 +02:00
internal.h
Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
2017-09-13 09:11:44 -07:00
ioctl.c
vfs: swap names of {do,vfs}_clone_file_range()
2018-11-10 07:48:33 -08:00
iomap.c
iomap: Fix pipe page leakage during splicing
2019-12-17 20:38:57 +01:00
Kconfig
fs/Kconfig: kill CONFIG_PERCPU_RWSEM some more
2017-07-12 16:26:00 -07:00
Kconfig.binfmt
…
libfs.c
libfs: fix infoleak in simple_attr_read()
2020-04-02 16:34:35 +02:00
locks.c
locks: print unsigned ino in /proc/locks
2020-01-09 10:17:55 +01:00
Makefile
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
mbcache.c
mbcache: initialize entry->e_referenced in mb_cache_entry_create()
2018-02-22 15:42:25 +01:00
mount.h
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
mpage.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
namei.c
namei: only return -ECHILD from follow_dotdot_rcu()
2020-03-11 18:02:53 +01:00
namespace.c
fs/namespace.c: fix mountpoint reference counter race
2020-05-02 17:24:20 +02:00
no-block.c
…
nsfs.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
open.c
cifs_atomic_open(): fix double-put on late allocation failure
2020-03-20 10:54:16 +01:00
pipe.c
fs: prevent page refcount overflow in pipe_buf_get
2019-05-04 09:15:18 +02:00
pnode.c
propagate_one(): mnt_set_mountpoint() needs mount_lock
2020-05-02 17:24:47 +02:00
pnode.h
…
posix_acl.c
…
proc_namespace.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
read_write.c
vfs: avoid problematic remapping requests into partial EOF block
2019-12-01 09:13:51 +01:00
readdir.c
filldir[64]: remove WARN_ON_ONCE() for bad directory entries
2020-01-04 14:00:04 +01:00
select.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
seq_file.c
seq_file: fix incomplete reset on read from zero offset
2018-02-22 15:42:28 +01:00
signalfd.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
splice.c
fs: prevent page refcount overflow in pipe_buf_get
2019-05-04 09:15:18 +02:00
stack.c
…
stat.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
statfs.c
vfs: Fix EOVERFLOW testing in put_compat_statfs64
2019-10-11 18:18:48 +02:00
super.c
fs: don't scan the inode cache before SB_BORN is set
2018-05-30 07:51:47 +02:00
sync.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
timerfd.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
userfaultfd.c
userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK
2020-01-04 13:59:58 +01:00
utimes.c
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
2017-11-02 11:10:55 +01:00
xattr.c
sysfs: Do not return POSIX ACL xattrs via listxattr
2018-10-10 08:54:27 +02:00