linux/fs
Jeff Layton ce2ac52105 cifs: ensure that cifs_get_root() only traverses directories
Kjell Braden reported this oops:

[  833.211970] BUG: unable to handle kernel NULL pointer dereference at           (null)
[  833.212816] IP: [<          (null)>]           (null)
[  833.213280] PGD 1b9b2067 PUD e9f7067 PMD 0
[  833.213874] Oops: 0010 [#1] SMP
[  833.214344] CPU 0
[  833.214458] Modules linked in: des_generic md4 nls_utf8 cifs vboxvideo drm snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq bnep rfcomm snd_timer bluetooth snd_seq_device ppdev snd vboxguest parport_pc joydev mac_hid soundcore snd_page_alloc psmouse i2c_piix4 serio_raw lp parport usbhid hid e1000
[  833.215629]
[  833.215629] Pid: 1752, comm: mount.cifs Not tainted 3.0.0-rc7-bisectcifs-fec11dd9a0+ #18 innotek GmbH VirtualBox/VirtualBox
[  833.215629] RIP: 0010:[<0000000000000000>]  [<          (null)>]           (null)
[  833.215629] RSP: 0018:ffff8800119c9c50  EFLAGS: 00010282
[  833.215629] RAX: ffffffffa02186c0 RBX: ffff88000c427780 RCX: 0000000000000000
[  833.215629] RDX: 0000000000000000 RSI: ffff88000c427780 RDI: ffff88000c4362e8
[  833.215629] RBP: ffff8800119c9c88 R08: ffff88001fc15e30 R09: 00000000d69515c7
[  833.215629] R10: ffffffffa0201972 R11: ffff88000e8f6a28 R12: ffff88000c4362e8
[  833.215629] R13: 0000000000000000 R14: 0000000000000000 R15: ffff88001181aaa6
[  833.215629] FS:  00007f2986171700(0000) GS:ffff88001fc00000(0000) knlGS:0000000000000000
[  833.215629] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  833.215629] CR2: 0000000000000000 CR3: 000000001b982000 CR4: 00000000000006f0
[  833.215629] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  833.215629] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  833.215629] Process mount.cifs (pid: 1752, threadinfo ffff8800119c8000, task ffff88001c1c16f0)
[  833.215629] Stack:
[  833.215629]  ffffffff8116a9b5 ffff8800119c9c88 ffffffff81178075 0000000000000286
[  833.215629]  0000000000000000 ffff88000c4276c0 ffff8800119c9ce8 ffff8800119c9cc8
[  833.215629]  ffffffff8116b06e ffff88001bc6fc00 ffff88000c4276c0 ffff88000c4276c0
[  833.215629] Call Trace:
[  833.215629]  [<ffffffff8116a9b5>] ? d_alloc_and_lookup+0x45/0x90
[  833.215629]  [<ffffffff81178075>] ? d_lookup+0x35/0x60
[  833.215629]  [<ffffffff8116b06e>] __lookup_hash.part.14+0x9e/0xc0
[  833.215629]  [<ffffffff8116b1d6>] lookup_one_len+0x146/0x1e0
[  833.215629]  [<ffffffff815e4f7e>] ? _raw_spin_lock+0xe/0x20
[  833.215629]  [<ffffffffa01eef0d>] cifs_do_mount+0x26d/0x500 [cifs]
[  833.215629]  [<ffffffff81163bd3>] mount_fs+0x43/0x1b0
[  833.215629]  [<ffffffff8117d41a>] vfs_kern_mount+0x6a/0xd0
[  833.215629]  [<ffffffff8117e584>] do_kern_mount+0x54/0x110
[  833.215629]  [<ffffffff8117fdc2>] do_mount+0x262/0x840
[  833.215629]  [<ffffffff81108a0e>] ? __get_free_pages+0xe/0x50
[  833.215629]  [<ffffffff8117f9ca>] ? copy_mount_options+0x3a/0x180
[  833.215629]  [<ffffffff8118075d>] sys_mount+0x8d/0xe0
[  833.215629]  [<ffffffff815ece82>] system_call_fastpath+0x16/0x1b
[  833.215629] Code:  Bad RIP value.
[  833.215629] RIP  [<          (null)>]           (null)
[  833.215629]  RSP <ffff8800119c9c50>
[  833.215629] CR2: 0000000000000000
[  833.238525] ---[ end trace ec00758b8d44f529 ]---

When walking down the path on the server, it's possible to hit a
symlink. The path walking code assumes that the caller will handle that
situation properly, but cifs_get_root() isn't set up for it. This patch
prevents the oops by simply returning an error.

A better solution would be to try and chase the symlinks here, but that's
fairly complicated to handle.

Fixes:

    https://bugzilla.kernel.org/show_bug.cgi?id=53221

Reported-and-tested-by: Kjell Braden <afflux@pentabarf.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2013-02-27 16:35:23 -06:00
..
9p Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
adfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
affs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
afs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
autofs4 fs: change return values from -EACCES to -EPERM 2013-02-26 02:46:14 -05:00
befs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
bfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
cachefiles
ceph Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
cifs cifs: ensure that cifs_get_root() only traverses directories 2013-02-27 16:35:23 -06:00
coda Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
configfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
cramfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
debugfs
devpts userns: Allow the userns root to mount of devpts 2013-01-26 22:22:21 -08:00
dlm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
ecryptfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
efs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
exofs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
exportfs
ext2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
ext3 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
ext4 This fixes a real brown paper bag bug which causes ext4 to choke on 2013-02-27 12:22:30 -08:00
f2fs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
fat new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
freevxfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
fscache
fuse Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
gfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
hfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
hfsplus new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
hostfs hostfs: directory methods have no business in non-directory inode_operations 2013-02-22 23:31:37 -05:00
hpfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
hppfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
hugetlbfs hugetlb_file_setup(): use d_alloc_pseudo() 2013-02-26 02:45:52 -05:00
isofs fs: encode_fh: return FILEID_INVALID if invalid fid_type 2013-02-26 02:46:10 -05:00
jbd
jbd2 jbd2: use module parameters instead of debugfs for jbd_debug 2013-02-09 16:29:20 -05:00
jffs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
jfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
lockd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
logfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
minix new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
ncpfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
nfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
nfs_common nfs_common: Update the translation between nfsv3 acls linux posix acls 2013-02-13 06:15:14 -08:00
nfsd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
nilfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
nls
notify Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
ntfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
ocfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
omfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
openpromfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
proc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
pstore A few fixes to reduce places where pstore might hang 2013-02-21 09:38:18 -08:00
qnx4 new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
qnx6 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
quota
ramfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
reiserfs fs: encode_fh: return FILEID_INVALID if invalid fid_type 2013-02-26 02:46:10 -05:00
romfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
squashfs new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
sysfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
sysv new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
ubifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
udf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
ufs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
xfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
aio.c mm: make do_mmap_pgoff return populate as a size in bytes, not as a bool 2013-02-23 17:50:11 -08:00
anon_inodes.c get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero 2013-02-26 02:46:11 -05:00
attr.c
bad_inode.c
binfmt_aout.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
binfmt_elf_fdpic.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
binfmt_elf.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
binfmt_em86.c
binfmt_flat.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
binfmt_misc.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
binfmt_script.c
binfmt_som.c
bio-integrity.c
bio.c
block_dev.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
buffer.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
compat.c switch timerfd compat syscalls to COMPAT_SYSCALL_DEFINE 2013-02-03 15:09:25 -05:00
coredump.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
coredump.h
dcache.c vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op 2013-02-26 02:46:09 -05:00
dcookies.c
direct-io.c fs: Fix possible use-after-free with AIO 2013-02-22 23:31:36 -05:00
drop_caches.c
eventfd.c
eventpoll.c
exec.c fs/exec.c: make bprm_mm_init() static 2013-02-26 02:46:13 -05:00
fcntl.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
fhandle.c
fifo.c
file_table.c fs: Preserve error code in get_empty_filp(), part 2 2013-02-22 23:31:32 -05:00
file.c locking: Various static lock initializer fixes 2013-02-19 08:42:45 +01:00
filesystems.c
fs_struct.c
fs-writeback.c
generic_acl.c
inode.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
internal.h
ioctl.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
ioprio.c
Kconfig
Kconfig.binfmt
libfs.c
locks.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
Makefile
mbcache.c
mount.h
mpage.c
namei.c vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op 2013-02-26 02:46:09 -05:00
namespace.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
no-block.c
open.c get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero 2013-02-26 02:46:11 -05:00
pipe.c fs: Preserve error code in get_empty_filp(), part 2 2013-02-22 23:31:32 -05:00
pnode.c
pnode.h
posix_acl.c
proc_namespace.c
read_write.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
read_write.h
readdir.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
select.c sched/rt: Move rt specific bits into new header file 2013-02-07 20:51:08 +01:00
seq_file.c
signalfd.c
splice.c export kernel_write(), convert open-coded instances 2013-02-26 02:46:11 -05:00
stack.c
stat.c switch vfs_getattr() to struct path 2013-02-26 02:46:08 -05:00
statfs.c
super.c
sync.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
timerfd.c switch timerfd compat syscalls to COMPAT_SYSCALL_DEFINE 2013-02-03 15:09:25 -05:00
utimes.c
xattr_acl.c
xattr.c