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linux/fs
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Oleg Nesterov a2a8474c3f exec: do not sleep in TASK_TRACED under ->cred_guard_mutex 
Tom Horsley reports that his debugger hangs when it tries to read
/proc/pid_of_tracee/maps, this happens since

	"mm_for_maps: take ->cred_guard_mutex to fix the race with exec"
	04b836cbf19e885f8366bccb2e4b0474346c02d

commit in 2.6.31.

But the root of the problem lies in the fact that do_execve() path calls
tracehook_report_exec() which can stop if the tracer sets PT_TRACE_EXEC.

The tracee must not sleep in TASK_TRACED holding this mutex.  Even if we
remove ->cred_guard_mutex from mm_for_maps() and proc_pid_attr_write(),
another task doing PTRACE_ATTACH should not hang until it is killed or the
tracee resumes.

With this patch do_execve() does not use ->cred_guard_mutex directly and
we do not hold it throughout, instead:

	- introduce prepare_bprm_creds() helper, it locks the mutex
	  and calls prepare_exec_creds() to initialize bprm->cred.

	- install_exec_creds() drops the mutex after commit_creds(),
	  and thus before tracehook_report_exec()->ptrace_stop().

	  or, if exec fails,

	  free_bprm() drops this mutex when bprm->cred != NULL which
	  indicates install_exec_creds() was not called.

Reported-by: Tom Horsley <tom.horsley@att.net>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-05 11:30:42 -07:00
..
9p 9p: remove unnecessary v9fses->options which duplicates the mount string 2009-08-17 16:42:28 -05:00
adfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
affs affs: add ->sync_fs 2009-06-11 21:36:14 -04:00
afs AFS: Stop readlink() on AFS crashing due to NULL 'file' ptr 2009-08-27 12:22:08 -07:00
autofs switch follow_down() 2009-06-11 21:36:01 -04:00
autofs4 autofs4 - fix missed case when changing to use struct path 2009-08-31 17:44:05 -10:00
befs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-06-17 08:46:57 -07:00
bfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
btrfs btrfs: fix inode rbtree corruption 2009-08-21 10:09:44 +02:00
cachefiles enforce ->sync_fs is only called for rw superblock 2009-06-11 21:36:06 -04:00
cifs [CIFS] Update readme to reflect forceuid mount parms 2009-08-04 03:53:28 +00:00
coda splice: implement default splice_read method 2009-05-11 14:13:10 +02:00
configfs configfs: Rework configfs_depend_item() locking and make lockdep happy 2009-04-30 10:48:26 -07:00
cramfs fs/cramfs: return f_fsid for statfs(2) 2009-04-02 19:05:08 -07:00
debugfs debugfs: use specified mode to possibly mark files read/write only 2009-06-15 21:30:28 -07:00
devpts devpts: remove module-related code 2009-06-24 08:15:24 -04:00
dlm dlm: free socket in error exit path 2009-07-14 12:28:43 -05:00
ecryptfs eCryptfs: parse_tag_3_packet check tag 3 packet encrypted key size 2009-07-28 14:26:06 -07:00
efs get rid of BKL in fs/efs 2009-06-17 00:36:36 -04:00
exofs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
exportfs
ext2 headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
ext3 ext3: Improve error message that changing journaling mode on remount is not possible 2009-08-24 16:48:45 +02:00
ext4 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 2009-07-13 16:39:25 -07:00
fat headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
freevxfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
fscache FS-Cache: Fixup renamed filenames in comments in internal.h 2009-05-27 10:20:13 -07:00
fuse Revert "fuse: Fix build error" as unnecessary 2009-07-11 11:22:34 -07:00
gfs2 GFS2: Fix permissions on "recover" file 2009-08-14 14:04:46 +01:00
hfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
hfsplus headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
hostfs hostfs: set maximum filesize in superblock for proper LFS support 2009-06-30 18:56:03 -07:00
hpfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
hppfs hppfs: hppfs_read_file() may return -ERROR 2009-04-02 19:04:53 -07:00
hugetlbfs mm: fix hugetlb bug due to user_shm_unlock call 2009-08-24 12:53:01 -07:00
isofs isofs: fix Joliet regression 2009-07-10 19:18:59 -07:00
jbd jbd: fix race between write_metadata_buffer and get_write_access 2009-07-21 11:54:42 +02:00
jbd2 jbd2: fix race between write_metadata_buffer and get_write_access 2009-07-13 17:55:35 -04:00
jffs2 jffs2: Fix return value from jffs2_do_readpage_nolock() 2009-08-04 12:13:06 +01:00
jfs jfs: Fix early release of acl in jfs_get_acl 2009-07-23 11:08:36 -05:00
lockd headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
minix Making fs/minix/minix.h double including safe 2009-06-22 11:34:42 -07:00
ncpfs NLS: update handling of Unicode 2009-06-15 21:44:43 -07:00
nfs NFSv4: Fix an infinite looping problem with the nfs4_state_manager 2009-08-24 16:28:42 -07:00
nfs_common
nfsd headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
nilfs2 nilfs2: fix oopses with doubly mounted snapshots 2009-08-19 02:10:13 +09:00
nls NLS: update handling of Unicode 2009-06-15 21:44:43 -07:00
notify inotify: update the group mask on mark addition 2009-08-28 12:51:14 -04:00
ntfs ntfs: use is_power_of_2() function for clarity. 2009-06-16 19:47:48 -07:00
ocfs2 Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2 2009-08-24 14:41:28 -07:00
omfs switch omfs to simple_fsync() 2009-06-11 21:36:13 -04:00
openpromfs
partitions partitions: fix broken uevent_suppress conversion 2009-07-12 13:02:09 -07:00
proc mm: revert "oom: move oom_adj value" 2009-08-18 16:31:13 -07:00
qnx4 fs/qnx4: sanitize includes 2009-06-11 21:36:12 -04:00
quota quota: Silence lockdep on quota_on 2009-07-30 17:31:23 +02:00
ramfs fs/ramfs/file-nommu.c needs include/linux/sched.h 2009-07-29 19:10:36 -07:00
reiserfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
romfs ROMFS: romfs_dev_read() error ignored 2009-05-09 10:49:41 -04:00
smbfs push BKL down into ->put_super 2009-06-11 21:36:07 -04:00
squashfs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
sysfs sysfs: fix hardlink count on device_move 2009-07-28 13:45:21 -07:00
sysv get rid of BKL in fs/sysv 2009-06-17 00:36:37 -04:00
ubifs headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
udf udf: Fix loading of VAT inode when drive wrongly reports number of recorded blocks 2009-07-30 17:28:26 +02:00
ufs ufs: sector_t cannot be negative 2009-06-18 13:03:46 -07:00
xfs xfs: fix locking in xfs_iget_cache_hit 2009-08-17 01:23:48 -05:00
aio.c eventfd: revised interface and cleanups 2009-06-30 18:55:58 -07:00
anon_inodes.c fs: Provide empty .set_page_dirty() aop for anon inodes 2009-06-18 14:46:10 +02:00
attr.c
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c elf_core_dump: use rcu_read_lock() to access ->real_parent 2009-06-18 13:03:52 -07:00
binfmt_elf.c elf: fix one check-after-use 2009-07-01 11:14:28 -07:00
binfmt_em86.c
binfmt_flat.c flat: fix uninitialized ptr with shared libs 2009-08-07 10:39:57 -07:00
binfmt_misc.c
binfmt_script.c
binfmt_som.c Don't crap into descriptor table in binfmt_som 2009-03-31 23:00:28 -04:00
bio-integrity.c block: Create bip slabs with embedded integrity vectors 2009-07-01 10:56:25 +02:00
bio.c block: fix sg SG_DXFER_TO_FROM_DEV regression 2009-07-10 20:31:53 +02:00
block_dev.c PM / Hibernate: Replace bdget call with simple atomic_inc of i_count 2009-07-29 21:07:55 +02:00
buffer.c Re-introduce page mapping check in mark_buffer_dirty() 2009-08-21 17:40:08 -07:00
char_dev.c headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
compat_binfmt_elf.c
compat_ioctl.c compat_ioctl: hook up compat handler for FIEMAP ioctl 2009-08-07 10:39:56 -07:00
compat.c exec: do not sleep in TASK_TRACED under ->cred_guard_mutex 2009-09-05 11:30:42 -07:00
dcache.c dcache: extrace and use d_unlinked() 2009-06-11 21:36:06 -04:00
dcookies.c
direct-io.c block: Do away with the notion of hardsect_size 2009-05-22 23:22:54 +02:00
drop_caches.c mm: remove __invalidate_mapping_pages variant 2009-06-16 19:47:43 -07:00
eventfd.c eventfd: revised interface and cleanups 2009-06-30 18:55:58 -07:00
eventpoll.c epoll: fix nested calls support 2009-06-18 13:03:41 -07:00
exec.c exec: do not sleep in TASK_TRACED under ->cred_guard_mutex 2009-09-05 11:30:42 -07:00
fcntl.c headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
fifo.c
file_table.c fs: move mark_files_ro into file_table.c 2009-06-11 21:36:02 -04:00
file.c
filesystems.c fs: Mark get_filesystem_list() as __init function. 2009-04-20 23:02:52 -04:00
fs_struct.c Get rid of indirect include of fs_struct.h 2009-03-31 23:00:27 -04:00
fs-writeback.c cleanup __writeback_single_inode 2009-06-24 08:15:26 -04:00
generic_acl.c New helper - current_umask() 2009-03-31 23:00:26 -04:00
inode.c vfs: add __destroy_inode 2009-08-07 14:38:29 -03:00
internal.h Trim a bit of crap from fs.h 2009-06-11 21:36:07 -04:00
ioctl.c fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls 2009-06-24 08:15:27 -04:00
ioprio.c
Kconfig fs/Kconfig: move nilfs2 out 2009-07-14 12:34:17 +09:00
Kconfig.binfmt
libfs.c vfs: make get_sb_pseudo set s_maxbytes to value that can be cast to signed 2009-08-18 16:31:12 -07:00
locks.c lockd: call locks_release_private to cleanup per-filesystem state 2009-04-24 16:36:03 -04:00
Makefile nilfs2: update makefile and Kconfig 2009-04-07 08:31:16 -07:00
mbcache.c
mpage.c ext4: Properly initialize the buffer_head state 2009-05-13 15:13:42 -04:00
namei.c integrity: add ima_counts_put (updated) 2009-06-29 08:59:10 +10:00
namespace.c vfs: mnt_want_write_file(): fix special file handling 2009-08-07 10:39:56 -07:00
nfsctl.c
no-block.c
open.c fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls 2009-06-24 08:15:27 -04:00
pipe.c lockdep: Fix lockdep annotation for pipe_double_lock() 2009-07-22 21:14:14 +02:00
pnode.c
pnode.h
posix_acl.c
read_write.c splice: implement default splice_read method 2009-05-11 14:13:10 +02:00
read_write.h
readdir.c
select.c poll/select: initialize triggered field of struct poll_wqueues 2009-08-15 18:40:11 -07:00
seq_file.c seq_file: add function to write binary data 2009-06-18 13:03:57 -07:00
signalfd.c
splice.c splice: fix kmaps in default_file_splice_write() 2009-05-19 11:37:46 +02:00
stack.c
stat.c kill vfs_stat_fd / vfs_lstat_fd 2009-04-20 23:02:52 -04:00
super.c ... and the same for vfsmount id/mount group id 2009-06-24 08:15:26 -04:00
sync.c sys_sync(): fix 16% performance regression in ffsb create_4k test 2009-07-06 13:57:03 -07:00
timerfd.c
utimes.c
xattr_acl.c
xattr.c fs: introduce mnt_clone_write 2009-06-11 21:36:02 -04:00