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b66c598401
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Kees Cook b66c598401 exec: do not leave bprm->interp on stack 
If a series of scripts are executed, each triggering module loading via
unprintable bytes in the script header, kernel stack contents can leak
into the command line.

Normally execution of binfmt_script and binfmt_misc happens recursively.
However, when modules are enabled, and unprintable bytes exist in the
bprm->buf, execution will restart after attempting to load matching
binfmt modules.  Unfortunately, the logic in binfmt_script and
binfmt_misc does not expect to get restarted.  They leave bprm->interp
pointing to their local stack.  This means on restart bprm->interp is
left pointing into unused stack memory which can then be copied into the
userspace argv areas.

After additional study, it seems that both recursion and restart remains
the desirable way to handle exec with scripts, misc, and modules.  As
such, we need to protect the changes to interp.

This changes the logic to require allocation for any changes to the
bprm->interp.  To avoid adding a new kmalloc to every exec, the default
value is left as-is.  Only when passing through binfmt_script or
binfmt_misc does an allocation take place.

For a proof of concept, see DoTest.sh from:

   http://www.halfdog.net/Security/2012/LinuxKernelBinfmtScriptStackDataDisclosure/

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: halfdog <me@halfdog.net>
Cc: P J P <ppandit@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-20 17:40:19 -08:00
..
9p The following changes since commit 4cbe5a555f: 2012-10-12 09:59:23 +09:00
adfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
affs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
afs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
autofs4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-17 15:44:47 -08:00
befs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
bfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
btrfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2012-12-18 09:42:05 -08:00
cachefiles fs: cachefiles: add support for large files in filesystem caching 2012-07-30 17:25:21 -07:00
ceph ceph: fix dentry reference leak in ceph_encode_fh() 2012-12-18 15:02:11 -08:00
cifs lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
coda fs: push rcu_barrier() from deactivate_locked_super() to filesystems 2012-10-02 21:35:55 -04:00
configfs lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
cramfs userns: Convert cramfs to use kuid/kgid where appropriate 2012-09-21 03:13:08 -07:00
debugfs fs/debugsfs: remove unnecessary inode->i_private initialization 2012-11-15 17:46:42 -08:00
devpts TTY: devpts, document devpts inode operations 2012-10-22 16:50:13 -07:00
dlm dlm: fix lvb invalidation conditions 2012-11-16 11:20:42 -06:00
ecryptfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
efs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
exofs exofs: don't leak io_state and pages on read error 2012-12-14 12:17:32 +02:00
exportfs fs, exportfs: add exportfs_encode_inode_fh() helper 2012-12-17 17:15:27 -08:00
ext2 ext2: fix return values on parse_options() failure 2012-10-09 23:23:53 +02:00
ext3 lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
ext4 lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
fat fs/fat: strip "cp" prefix from codepage in display 2012-12-17 17:15:22 -08:00
freevxfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
fscache
fuse Merge branch 'akpm' (Andrew's patch-bomb) 2012-12-17 20:58:12 -08:00
gfs2 lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
hfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
hfsplus Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
hostfs Merge branch 'for-linus-37rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2012-10-10 11:15:20 +09:00
hpfs hpfs: drop lock/unlock super 2012-10-09 23:33:38 -04:00
hppfs pidns: Use task_active_pid_ns where appropriate 2012-11-19 05:59:09 -08:00
hugetlbfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
isofs tmpfs,ceph,gfs2,isofs,reiserfs,xfs: fix fh_len checking 2012-10-09 23:33:55 -04:00
jbd Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-12-13 12:00:02 -08:00
jbd2 There are two major features for this merge window. The first is 2012-12-16 17:33:01 -08:00
jffs2 jffs2: hold erase_completion_lock on exit 2012-11-18 11:59:01 +02:00
jfs jfs: Fix FITRIM argument handling 2012-10-17 09:18:38 -05:00
lockd lockd: Remove BUG_ON()s from fs/lockd/clntproc.c 2012-11-04 14:43:40 -05:00
logfs Fix misspellings of "whether" in comments. 2012-11-19 14:31:35 +01:00
minix Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
ncpfs propagate name change to comments in kernel source 2012-12-06 10:39:54 +01:00
nfs NFS client updates for Linux 3.8 2012-12-18 09:36:34 -08:00
nfs_common
nfsd UAPI Disintegration 2012-10-09 2012-10-09 18:35:22 -04:00
nilfs2 mm: redefine address_space.assoc_mapping 2012-12-11 17:22:26 -08:00
nls nls: fix (and rename) mac NLS table files and config options 2012-06-01 19:51:22 -07:00
notify fs, fanotify: add @mflags field to fanotify output 2012-12-17 17:15:28 -08:00
ntfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
ocfs2 lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
omfs omfs: convert to use beXX_add_cpu() 2012-10-06 03:05:31 +09:00
openpromfs fs: push rcu_barrier() from deactivate_locked_super() to filesystems 2012-10-02 21:35:55 -04:00
proc Merge branch 'akpm' (Andrew's patch-bomb) 2012-12-17 20:58:12 -08:00
pstore lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
qnx4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
qnx6 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
quota quota: Use the pre-processor to compile out quotactl_cmd_write when !CONFIG_BLOCK 2012-12-13 16:33:24 +01:00
ramfs don't pass nameidata to ->create() 2012-07-14 16:34:47 +04:00
reiserfs reiserfs: Move quota calls out of write lock 2012-11-19 21:34:33 +01:00
romfs fs: push rcu_barrier() from deactivate_locked_super() to filesystems 2012-10-02 21:35:55 -04:00
squashfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
sysfs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-17 15:44:47 -08:00
sysv sysv: drop lock/unlock super 2012-10-09 23:33:39 -04:00
ubifs ubifs: use prandom_bytes 2012-12-17 17:15:26 -08:00
udf udf: remove un-needed variable from inode_getblk 2012-12-13 16:33:23 +01:00
ufs ufs: drop lock/unlock super 2012-10-09 23:33:39 -04:00
xfs xfs: fix sparse reported log CRC endian issue 2012-12-03 12:10:59 -06:00
aio.c aio: now fput() is OK from interrupt context; get rid of manual delayed __fput() 2012-07-22 23:57:59 +04:00
anon_inodes.c
attr.c userns: Allow chown and setgid preservation 2012-11-20 04:17:24 -08:00
bad_inode.c lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
binfmt_aout.c get rid of pt_regs argument of ->load_binary() 2012-11-28 21:53:38 -05:00
binfmt_elf_fdpic.c get rid of pt_regs argument of ->load_binary() 2012-11-28 21:53:38 -05:00
binfmt_elf.c binfmt_elf: fix corner case kfree of uninitialized data 2012-12-17 17:15:19 -08:00
binfmt_em86.c exec: use -ELOOP for max recursion depth 2012-12-17 17:15:23 -08:00
binfmt_flat.c get rid of pt_regs argument of ->load_binary() 2012-11-28 21:53:38 -05:00
binfmt_misc.c exec: do not leave bprm->interp on stack 2012-12-20 17:40:19 -08:00
binfmt_script.c exec: do not leave bprm->interp on stack 2012-12-20 17:40:19 -08:00
binfmt_som.c get rid of pt_regs argument of ->load_binary() 2012-11-28 21:53:38 -05:00
bio-integrity.c block: Ues bi_pool for bio_integrity_alloc() 2012-09-09 10:35:38 +02:00
bio.c vfs: fix: don't increase bio_slab_max if krealloc() fails 2012-10-22 22:00:26 +02:00
block_dev.c lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
buffer.c fs/buffer.c: remove redundant initialization in alloc_page_buffers() 2012-12-12 17:38:35 -08:00
char_dev.c char_dev: pin parent kobject 2012-10-22 08:50:37 +03:00
compat_binfmt_elf.c coredump: extend core dump note section to contain file names of mapped files 2012-10-06 03:05:17 +09:00
compat_ioctl.c Merge 3.7-rc3 into tty-next 2012-10-29 09:00:57 -07:00
compat.c vfs: define struct filename and have getname() return it 2012-10-12 20:14:55 -04:00
coredump.c do_coredump(): get rid of pt_regs argument 2012-11-29 00:01:25 -05:00
coredump.h coredump: update coredump-related headers 2012-10-06 03:05:15 +09:00
dcache.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
dcookies.c
direct-io.c direct-io: don't read inode->i_blkbits multiple times 2012-11-29 12:38:44 -08:00
drop_caches.c
eventfd.c fs, eventfd: add procfs fdinfo helper 2012-12-17 17:15:27 -08:00
eventpoll.c fs, epoll: add procfs fdinfo helper 2012-12-17 17:15:27 -08:00
exec.c exec: do not leave bprm->interp on stack 2012-12-20 17:40:19 -08:00
fcntl.c Fix F_DUPFD_CLOEXEC breakage 2012-10-09 15:52:31 +09:00
fhandle.c Fix misspellings of "whether" in comments. 2012-11-19 14:31:35 +01:00
fifo.c fifo: Do not restart open() if it already found a partner 2012-07-16 08:33:14 -07:00
file_table.c lglock: add DEFINE_STATIC_LGLOCK() 2012-10-10 01:15:44 -04:00
file.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2012-12-12 12:22:13 -08:00
filesystems.c vfs: define struct filename and have getname() return it 2012-10-12 20:14:55 -04:00
fs_struct.c kill daemonize() 2012-11-28 21:49:02 -05:00
fs-writeback.c writeback: fix a typo in comment 2012-12-12 17:38:34 -08:00
generic_acl.c userns: Pass a userns parameter into posix_acl_to_xattr and posix_acl_from_xattr 2012-09-18 01:01:35 -07:00
inode.c mm: redefine address_space.assoc_mapping 2012-12-11 17:22:26 -08:00
internal.h writeback: put unused inodes to LRU after writeback completion 2012-11-26 17:41:24 -08:00
ioctl.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
ioprio.c Merge branch 'for-3.5/core' of git://git.kernel.dk/linux-block 2012-05-30 08:52:42 -07:00
Kconfig ext4: Remove CONFIG_EXT4_FS_XATTR 2012-12-10 16:30:43 -05:00
Kconfig.binfmt coredump: make core dump functionality optional 2012-10-06 03:05:15 +09:00
libfs.c lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
locks.c UAPI Disintegration 2012-10-09 2012-10-09 18:35:22 -04:00
Makefile coredump: make core dump functionality optional 2012-10-06 03:05:15 +09:00
mbcache.c
mount.h proc: Usable inode numbers for the namespace file descriptors. 2012-11-20 04:19:49 -08:00
mpage.c
namei.c lookup_one_len: don't accept . and .. 2012-11-29 22:17:21 -05:00
namespace.c userns: Require CAP_SYS_ADMIN for most uses of setns. 2012-12-14 16:12:03 -08:00
no-block.c
open.c vfs: Allow chroot if you have CAP_SYS_CHROOT in your user namespace 2012-11-19 05:59:17 -08:00
pipe.c pipe(2) - race-free error recovery 2012-09-26 21:08:52 -04:00
pnode.c VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors 2012-07-14 16:37:27 +04:00
pnode.h vfs: Only support slave subtrees across different user namespaces 2012-11-19 05:59:20 -08:00
posix_acl.c userns: Convert vfs posix_acl support to use kuids and kgids 2012-09-18 01:01:35 -07:00
proc_namespace.c get rid of magic in proc_namespace.c 2012-07-14 16:32:48 +04:00
read_write.c lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
read_write.h compat: fs: Generic compat_sys_sendfile implementation 2012-10-02 21:35:55 -04:00
readdir.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
select.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
seq_file.c lseek: the "whence" argument is called "whence" 2012-12-17 17:15:12 -08:00
signalfd.c fs, epoll: add procfs fdinfo helper 2012-12-17 17:15:27 -08:00
splice.c writeback: remove nr_pages_dirtied arg from balance_dirty_pages_ratelimited_nr() 2012-12-11 17:22:21 -08:00
stack.c
stat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2012-10-02 20:25:04 -07:00
statfs.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
super.c vfs: drop lock/unlock super 2012-10-09 23:33:39 -04:00
sync.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
timerfd.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
utimes.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
xattr_acl.c userns: Fix posix_acl_file_xattr_userns gid conversion 2012-10-12 13:16:48 -07:00
xattr.c fs, xattr: fix bug when removing a name not in xattr list 2012-10-18 12:35:58 -07:00