remarkable-linux/fs
J. Bruce Fields 76f47128f9 nfsd: fix rare symlink decoding bug
An NFS operation that creates a new symlink includes the symlink data,
which is xdr-encoded as a length followed by the data plus 0 to 3 bytes
of zero-padding as required to reach a 4-byte boundary.

The vfs, on the other hand, wants null-terminated data.

The simple way to handle this would be by copying the data into a newly
allocated buffer with space for the final null.

The current nfsd_symlink code tries to be more clever by skipping that
step in the (likely) case where the byte following the string is already
0.

But that assumes that the byte following the string is ours to look at.
In fact, it might be the first byte of a page that we can't read, or of
some object that another task might modify.

Worse, the NFSv4 code tries to fix the problem by actually writing to
that byte.

In the NFSv2/v3 cases this actually appears to be safe:

	- nfs3svc_decode_symlinkargs explicitly null-terminates the data
	  (after first checking its length and copying it to a new
	  page).
	- NFSv2 limits symlinks to 1k.  The buffer holding the rpc
	  request is always at least a page, and the link data (and
	  previous fields) have maximum lengths that prevent the request
	  from reaching the end of a page.

In the NFSv4 case the CREATE op is potentially just one part of a long
compound so can end up on the end of a page if you're unlucky.

The minimal fix here is to copy and null-terminate in the NFSv4 case.
The nfsd_symlink() interface here seems too fragile, though.  It should
really either do the copy itself every time or just require a
null-terminated string.

Reported-by: Jeff Layton <jlayton@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2014-06-27 16:10:46 -04:00
..
9p Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
adfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
affs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
afs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
autofs4 fs/autofs4/dev-ioctl.c: add __init to autofs_dev_ioctl_init 2014-06-04 16:54:21 -07:00
befs fs/befs: kernel-doc fixes 2014-06-06 16:08:09 -07:00
bfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2014-06-21 14:21:43 -10:00
cachefiles fs/cachefiles: replace kerror by pr_err 2014-06-06 16:08:14 -07:00
ceph Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client 2014-06-12 23:06:23 -07:00
cifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
coda coda: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
configfs fs/configfs: use pr_fmt 2014-06-04 16:53:53 -07:00
cramfs Major changes for 3.14 include support for the newly added ZERO_RANGE 2014-04-04 15:39:39 -07:00
debugfs Major changes for 3.14 include support for the newly added ZERO_RANGE 2014-04-04 15:39:39 -07:00
devpts fs/devpts/inode.c: convert printk to pr_foo() 2014-06-06 16:08:14 -07:00
dlm dlm: keep listening connection alive with sctp mode 2014-06-12 10:26:14 -05:00
ecryptfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
efivarfs fs/efivarfs/super.c: use static const for dentry_operations 2014-06-04 16:54:14 -07:00
efs fs/efs: convert printk(KERN_DEBUG to pr_debug 2014-06-04 16:54:21 -07:00
exofs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
exportfs fs/exportfs/expfs.c: kernel-doc warning fixes 2014-06-04 16:54:14 -07:00
ext2 ->splice_write() via ->write_iter() 2014-06-12 00:18:51 -04:00
ext3 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
ext4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
f2fs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
fat Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
freevxfs Major changes for 3.14 include support for the newly added ZERO_RANGE 2014-04-04 15:39:39 -07:00
fscache fscache: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
fuse Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
gfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
hfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
hfsplus Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
hostfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
hpfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
hppfs
hugetlbfs fs/hugetlbfs/inode.c: remove null test before kfree 2014-06-04 16:54:11 -07:00
isofs Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2014-04-07 17:59:17 -07:00
jbd fs/jbd/revoke.c: replace shift loop by ilog2 2014-05-21 10:26:13 +02:00
jbd2 arch: Mass conversion of smp_mb__*() 2014-04-18 14:20:48 +02:00
jffs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
jfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
kernfs kernfs: move the last knowledge of sysfs out from kernfs 2014-06-03 08:11:18 -07:00
lockd Merge branch 'for-3.16' of git://linux-nfs.org/~bfields/linux 2014-06-10 11:50:57 -07:00
logfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
minix write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
ncpfs fs/ncpfs/getopt.c: replace simple_strtoul by kstrtoul 2014-06-04 16:54:21 -07:00
nfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
nfs_common
nfsd nfsd: fix rare symlink decoding bug 2014-06-27 16:10:46 -04:00
nilfs2 write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
nls nls: have register_nls() set ->owner 2014-01-25 03:14:05 -05:00
notify inotify: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
ntfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
ocfs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
omfs write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
openpromfs fs: push sync_filesystem() down to the file system's remount_fs() 2014-03-13 10:14:33 -04:00
proc Merge branch 'next' (accumulated 3.16 merge window patches) into master 2014-06-08 11:31:16 -07:00
pstore fs/pstore: logging clean-up 2014-06-06 16:08:13 -07:00
qnx4 fs: push sync_filesystem() down to the file system's remount_fs() 2014-03-13 10:14:33 -04:00
qnx6 fs: push sync_filesystem() down to the file system's remount_fs() 2014-03-13 10:14:33 -04:00
quota xfs: fix Q_XQUOTARM ioctl 2014-05-05 17:25:50 +10:00
ramfs ->splice_write() via ->write_iter() 2014-06-12 00:18:51 -04:00
reiserfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
romfs switch simple generic_file_aio_read() users to ->read_iter() 2014-05-06 17:37:55 -04:00
squashfs fs/squashfs/squashfs.h: replace pr_warning by pr_warn 2014-06-04 16:53:52 -07:00
sysfs kernfs: move the last knowledge of sysfs out from kernfs 2014-06-03 08:11:18 -07:00
sysv write_iter variants of {__,}generic_file_aio_write() 2014-05-06 17:38:00 -04:00
ubifs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
udf udf: switch to ->write_iter() 2014-05-06 17:39:36 -04:00
ufs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
xfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
aio.c Merge git://git.kvack.org/~bcrl/aio-next 2014-06-14 19:43:27 -05:00
anon_inodes.c vfs: Allocate anon_inode_inode in anon_inode_init() 2014-03-27 09:52:54 -07:00
attr.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
bad_inode.c
binfmt_aout.c dump_skip(): dump_seek() replacement taking coredump_params 2013-11-09 00:16:26 -05:00
binfmt_elf.c Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next 2014-06-05 08:05:29 -07:00
binfmt_elf_fdpic.c elf{,_fdpic} coredump: get rid of pointless if (siginfo->si_signo) 2013-11-09 00:16:30 -05:00
binfmt_em86.c file->f_op is never NULL... 2013-10-24 23:34:54 -04:00
binfmt_flat.c fs/binfmt_flat.c: make old_reloc() static 2014-06-04 16:54:21 -07:00
binfmt_misc.c binfmt_misc: add missing 'break' statement 2014-04-03 16:21:16 -07:00
binfmt_script.c
binfmt_som.c
block_dev.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
buffer.c mm: non-atomically mark page accessed during page cache allocation where possible 2014-06-04 16:54:10 -07:00
char_dev.c Merge branch 'for-3.13/core' of git://git.kernel.dk/linux-block 2013-11-14 12:08:14 +09:00
compat.c locks: rename file-private locks to "open file description locks" 2014-04-22 08:23:58 -04:00
compat_binfmt_elf.c binfmt_elf: add ELF_HWCAP2 to compat auxv entries 2014-03-04 08:05:21 +00:00
compat_ioctl.c fs/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types 2014-03-06 16:30:44 +01:00
coredump.c coredump: fix va_list corruption 2014-04-19 13:23:31 -07:00
dcache.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
dcookies.c fs/compat: fix lookup_dcookie() parameter handling 2014-01-29 16:22:40 -08:00
direct-io.c new helper: iov_iter_npages() 2014-05-06 17:32:52 -04:00
drop_caches.c fs: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
eventfd.c eventfd_ctx_fdget(): use fdget() instead of fget() 2014-01-25 03:13:04 -05:00
eventpoll.c epoll: fix use-after-free in eventpoll_release_file 2014-06-16 17:21:59 -10:00
exec.c perf: Differentiate exec() and non-exec() comm events 2014-06-06 07:56:22 +02:00
fcntl.c locks: rename file-private locks to "open file description locks" 2014-04-22 08:23:58 -04:00
fhandle.c
file.c fs/file.c: don't open-code kvfree() 2014-05-06 17:31:10 -04:00
file_table.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2014-06-12 10:30:18 -07:00
filesystems.c sys_sysfs: Add CONFIG_SYSFS_SYSCALL 2014-04-03 16:21:05 -07:00
fs-writeback.c One of the main highlights this time, is not the patches themselves 2014-04-04 14:49:16 -07:00
fs_struct.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
inode.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
internal.h get rid of s_files and files_lock 2013-11-09 00:16:20 -05:00
ioctl.c file->f_op is never NULL... 2013-10-24 23:34:54 -04:00
Kconfig kernfs: add CONFIG_KERNFS 2014-02-07 16:08:57 -08:00
Kconfig.binfmt
libfs.c fs/libfs.c: add generic data flush to fsync 2014-06-04 16:53:55 -07:00
locks.c locks: set fl_owner for leases back to current->files 2014-06-10 12:29:05 -04:00
Makefile block: move ioprio.c from fs/ to block/ 2014-05-19 11:02:18 -06:00
mbcache.c ext4: each filesystem creates and uses its own mb_cache 2014-03-18 19:24:49 -04:00
mount.h reduce m_start() cost... 2014-04-01 23:19:09 -04:00
mpage.c fs/block_dev.c: add bdev_read_page() and bdev_write_page() 2014-06-04 16:54:02 -07:00
namei.c fs,userns: Change inode_capable to capable_wrt_inode_uidgid 2014-06-10 13:57:22 -07:00
namespace.c VFS: Make delayed_free() call free_vfsmnt() 2014-04-01 23:19:18 -04:00
no-block.c
open.c new methods: ->read_iter() and ->write_iter() 2014-05-06 17:36:00 -04:00
pipe.c new helper: copy_page_from_iter() 2014-05-06 17:39:42 -04:00
pnode.c smarter propagate_mnt() 2014-04-01 23:19:08 -04:00
pnode.h smarter propagate_mnt() 2014-04-01 23:19:08 -04:00
posix_acl.c posix_acl: handle NULL ACL in posix_acl_equiv_mode 2014-05-06 13:58:42 -04:00
proc_namespace.c reduce m_start() cost... 2014-04-01 23:19:09 -04:00
read_write.c switch simple generic_file_aio_read() users to ->read_iter() 2014-05-06 17:37:55 -04:00
readdir.c fanotify: create FAN_ACCESS event for readdir 2014-06-04 16:53:52 -07:00
select.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-11-13 15:34:18 +09:00
seq_file.c seq_file: always clear m->count when we free m->buf 2013-11-18 19:07:53 -08:00
signalfd.c
splice.c Merge commit '9f12600fe425bc28f0ccba034a77783c09c15af4' into for-linus 2014-06-12 00:28:09 -04:00
stack.c
stat.c vfs: split out vfs_getattr_nosec 2013-11-09 00:16:31 -05:00
statfs.c
super.c fs/superblock: avoid locking counting inodes and dentries before reclaiming them 2014-06-04 16:54:11 -07:00
sync.c Revert "writeback: do not sync data dirtied after sync start" 2014-02-22 02:02:28 +01:00
timerfd.c timerfd: support CLOCK_BOOTTIME clock 2014-01-23 16:57:40 -08:00
utimes.c locks: break delegations on any attribute modification 2013-11-09 00:16:44 -05:00
xattr.c