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cb510b8172
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Alexey Dobriyan cb510b8172 seq_file: more atomicity in traverse() 
Original problem: in some circumstances seq_file interface can present
infinite proc file to the following script when normally said proc file is
finite:

	while read line; do
		[do something with $line]
	done </proc/$FILE

bash, to implement such loop does essentially

	read(0, buf, 128);
	[find \n]
	lseek(0, -difference, SEEK_CUR);

Consider, proc file prints list of objects each of them consists of many
lines, each line is shorter than 128 bytes.

Two objects in list, with ->index'es being 0 and 1.  Current one is 1, as
bash prints second object line by line.

Imagine first object being removed right before lseek().
traverse() will be called, because there is negative offset.
traverse() will reset ->index to 0 (!).
traverse() will call ->next() and get NULL in any usual iterate-over-list
code using list_for_each_entry_continue() and such. There is one object in
list now after all...
traverse() will return 0, lseek() will update file position and pretend
everything is OK.

So, what we have now: ->f_pos points to place where second object will be
printed, but ->index is 0.  seq_read() instead of returning EOF, will start
printing first line of first object every time it's called, until enough
objects are added to ->f_pos return in bounds.

Fix is to update ->index only after we're sure we saw enough objects down
the road.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:45 -07:00
..
9p 9p: re-enable mount time debug option 2007-07-14 15:14:14 -05:00
adfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
affs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
afs AFS: drop explicit extern 2007-07-16 09:05:43 -07:00
autofs Replace pid_t in autofs with struct pid reference 2007-05-11 08:29:36 -07:00
autofs4 Fix some coding-style errors in autofs 2007-05-11 08:29:36 -07:00
befs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
bfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
cifs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
coda wrong order of arguments of ->readdir() 2007-07-15 16:40:51 -07:00
configfs Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
cramfs mm: make read_cache_page synchronous 2007-05-07 12:12:51 -07:00
debugfs debugfs: add rename for debugfs files 2007-07-11 16:09:00 -07:00
devpts devpts: add fsnotify create event 2007-05-08 11:14:59 -07:00
dlm [DLM] dump more lock values 2007-07-09 08:24:13 +01:00
ecryptfs sysfs: kill unnecessary attribute->owner 2007-07-11 16:09:06 -07:00
efs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
exportfs header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
ext2 ext2: fix a comment when ext2_release_file() is called 2007-07-16 09:05:44 -07:00
ext3 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ext4 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
fat fat: gcc 4.3 warning fix 2007-07-16 09:05:42 -07:00
freevxfs vxfs warning fixes 2007-07-16 09:05:41 -07:00
fuse sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
gfs2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw 2007-07-10 13:56:13 -07:00
hfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hfsplus sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hostfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hpfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
hppfs
hugetlbfs shm: fix the filename of hugetlb sysv shared memory 2007-06-16 13:16:16 -07:00
isofs remove useless tolower in isofs 2007-07-16 09:05:43 -07:00
jbd jbd commit: fix transaction dropping 2007-07-16 09:05:34 -07:00
jbd2 jbd2 commit: fix transaction dropping 2007-07-16 09:05:34 -07:00
jffs2 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
jfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
lockd NLM: fix source address of callback to client 2007-07-10 23:40:49 -04:00
minix sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
msdos
ncpfs Only send SIGXFSZ when exceeding rlimits. 2007-07-16 09:05:43 -07:00
nfs Make NFS client use seq_list_xxx helpers 2007-07-16 09:05:42 -07:00
nfs_common
nfsd Merge git://git.linux-nfs.org/pub/linux/nfs-2.6 2007-07-13 16:46:18 -07:00
nls
ntfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ocfs2 sysfs: kill unnecessary attribute->owner 2007-07-11 16:09:06 -07:00
openpromfs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
partitions fix compiler warnings in acorn.c 2007-07-16 09:05:42 -07:00
proc /proc/*/environ: wrong placing of ptrace_may_attach() check 2007-07-16 09:05:44 -07:00
qnx4 sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
ramfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
reiserfs Only send SIGXFSZ when exceeding rlimits. 2007-07-16 09:05:43 -07:00
romfs Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
smbfs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
sysfs sysfs: add parameter "struct bin_attribute *" in .read/.write methods for sysfs binary attributes 2007-07-11 16:09:09 -07:00
sysv sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
udf UDF: check for allocated memory for inode data 2007-07-16 09:05:41 -07:00
ufs sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
vfat
xfs [XFS] Fix lockdep annotations for xfs_lock_inodes 2007-07-14 18:09:42 +10:00
aio.c signal/timer/event: KAIO eventfd support example 2007-05-11 08:29:37 -07:00
anon_inodes.c signal/timer/event fds: anonymous inode source 2007-05-11 08:29:36 -07:00
attr.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
bad_inode.c sendfile: remove bad_sendfile() from bad_file_ops 2007-07-10 08:04:15 +02:00
binfmt_aout.c
binfmt_elf_fdpic.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
binfmt_elf.c PIE randomization 2007-07-16 09:05:42 -07:00
binfmt_em86.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
binfmt_flat.c nommu: report correct errno in message 2007-06-08 17:23:32 -07:00
binfmt_misc.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
binfmt_script.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
binfmt_som.c
bio.c unexport bio_{,un}map_user 2007-07-10 08:03:34 +02:00
block_dev.c fs/block_dev.c: use list_for_each_entry() 2007-07-16 09:05:45 -07:00
buffer.c buffer: kill old incorrect comment 2007-07-16 09:05:45 -07:00
char_dev.c
compat_ioctl.c fix compat console unimap regression 2007-05-25 17:37:46 -07:00
compat.c optimize compat_core_sys_select() by a using stack space for small fd sets 2007-05-23 20:14:12 -07:00
dcache.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
dcookies.c
direct-io.c dio: remove bogus refcounting BUG_ON 2007-07-03 18:23:23 -07:00
dnotify.c
dquot.c circular locking dependency found in QUOTA OFF 2007-05-17 05:23:05 -07:00
drop_caches.c invalidate_mapping_pages(): add cond_resched 2007-07-16 09:05:36 -07:00
eventfd.c eventfd use waitqueue lock ... 2007-05-18 13:09:34 -07:00
eventpoll.c epoll: move kfree inside ep_free 2007-05-15 08:54:00 -07:00
exec.c uselib: add missing MNT_NOEXEC check 2007-05-23 20:14:13 -07:00
fcntl.c
fifo.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
file_table.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
file.c
filesystems.c add filesystem subtype support 2007-05-08 11:15:01 -07:00
fs-writeback.c
generic_acl.c
inode.c Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
inotify_user.c
inotify.c Introduce a handy list_first_entry macro 2007-05-08 11:15:11 -07:00
internal.h cleanup compat ioctl handling 2007-05-08 11:15:09 -07:00
ioctl.c vanishing ioctl handler debugging 2007-06-04 13:25:10 -07:00
ioprio.c
Kconfig 9p: Reorganization of 9p file system code 2007-07-14 15:13:40 -05:00
Kconfig.binfmt fs: Kill sh dependency for binfmt_flat. 2007-05-21 14:34:00 +09:00
libfs.c fs/libfs.c: >80 columns line break fix 2007-05-09 06:44:57 +02:00
locks.c Remove SLAB_CTOR_CONSTRUCTOR 2007-05-17 05:23:04 -07:00
Makefile signal/timer/event: eventfd core 2007-05-11 08:29:36 -07:00
mbcache.c
mpage.c consolidate generic_writepages and mpage_writepages 2007-05-11 08:29:35 -07:00
namei.c [PATCH] complete message queue auditing 2007-05-11 05:38:26 -04:00
namespace.c Make /proc/self/mounts(tats) use seq_list_xxx helpers 2007-07-16 09:05:42 -07:00
nfsctl.c
no-block.c
open.c O_CLOEXEC for SCM_RIGHTS 2007-07-16 09:05:45 -07:00
pipe.c pipe: add documentation and comments 2007-07-10 08:04:16 +02:00
pnode.c Introduce a handy list_first_entry macro 2007-05-08 11:15:11 -07:00
pnode.h
posix_acl.c
quota_v1.c
quota_v2.c
quota.c circular locking dependency found in QUOTA OFF 2007-05-17 05:23:05 -07:00
read_write.c Remove remnants of sendfile() 2007-07-10 08:04:15 +02:00
read_write.h
readdir.c ROUND_UP macro cleanup in fs/(select|compat|readdir).c 2007-05-08 11:15:09 -07:00
select.c Style fix in fs/select.c 2007-05-09 07:10:02 +02:00
seq_file.c seq_file: more atomicity in traverse() 2007-07-16 09:05:45 -07:00
signalfd.c avoid spurious POLLIN returns in signalfd 2007-06-28 11:34:54 -07:00
splice.c splice: fix offset mangling with direct splicing (sendfile) 2007-07-13 14:14:31 +02:00
stack.c
stat.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
super.c add filesystem subtype support 2007-05-08 11:15:01 -07:00
sync.c Introduce fixed sys_sync_file_range2() syscall, implement on PowerPC and ARM 2007-06-28 11:38:30 -07:00
timerfd.c timerfd use waitqueue lock ... 2007-05-18 13:09:34 -07:00
utimes.c Fix permission checking for the new utimensat() system call 2007-07-08 12:02:55 -07:00
xattr_acl.c
xattr.c [PATCH] audit inode for all xattr syscalls 2007-05-11 05:38:26 -04:00