Presently do_execve() turns PF_KTHREAD off before search_binary_handler().
THis has a theorical risk of PF_KTHREAD getting lost. We don't have to
turn PF_KTHREAD off in the ENOEXEC case.
This patch moves this flag modification to after the finding of the
executable file.
This is only a theorical issue because kthreads do not call do_execve()
directly. But fixing would be better.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We met a parameter truncated issue, consider following:
> echo "|/root/core_pattern_pipe_test %p /usr/libexec/blah-blah-blah \
%s %c %p %u %g 11 12345678901234567890123456789012345678 %t" > \
/proc/sys/kernel/core_pattern
This is okay because the strings is less than CORENAME_MAX_SIZE. "cat
/proc/sys/kernel/core_pattern" shows the whole string. but after we run
core_pattern_pipe_test in man page, we found last parameter was truncated
like below:
argc[10]=<12807486>
The root cause is core_pattern allows % specifiers, which need to be
replaced during parse time, but the replace may expand the strings to
larger than CORENAME_MAX_SIZE. So if the last parameter is % specifiers,
the replace code is using snprintf(out_ptr, out_end - out_ptr, ...), this
will write out of corename array.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Neil Horman <nhorman@tuxdriver.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec
itself and we can reuse ->cred_guard_mutex for it. Yes, concurrent
execve() has no worth.
Let's move ->cred_guard_mutex from task_struct to signal_struct. It
naturally prevent multiple-threads-inside-exec.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's pointless to kill a task if another thread sharing its mm cannot be
killed to allow future memory freeing. A subsequent patch will prevent
kills in such cases, but first it's necessary to have a way to flag a task
that shares memory with an OOM_DISABLE task that doesn't incur an
additional tasklist scan, which would make select_bad_process() an O(n^2)
function.
This patch adds an atomic counter to struct mm_struct that follows how
many threads attached to it have an oom_score_adj of OOM_SCORE_ADJ_MIN.
They cannot be killed by the kernel, so their memory cannot be freed in
oom conditions.
This only requires task_lock() on the task that we're operating on, it
does not require mm->mmap_sem since task_lock() pins the mm and the
operation is atomic.
[rientjes@google.com: changelog and sys_unshare() code]
[rientjes@google.com: protect oom_disable_count with task_lock in fork]
[rientjes@google.com: use old_mm for oom_disable_count in exec]
Signed-off-by: Ying Han <yinghan@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tony Luck reports that the addition of the access_ok() check in commit
0eead9ab41 ("Don't dump task struct in a.out core-dumps") broke the
ia64 compile due to missing the necessary header file includes.
Rather than add yet another include (<asm/unistd.h>) to make everything
happy, just uninline the silly core dump helper functions and move the
bodies to fs/exec.c where they make a lot more sense.
dump_seek() in particular was too big to be an inline function anyway,
and none of them are in any way performance-critical. And we really
don't need to mess up our include file headers more than they already
are.
Reported-and-tested-by: Tony Luck <tony.luck@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An execve with a very large total of argument/environment strings
can take a really long time in the execve system call. It runs
uninterruptibly to count and copy all the strings. This change
makes it abort the exec quickly if sent a SIGKILL.
Note that this is the conservative change, to interrupt only for
SIGKILL, by using fatal_signal_pending(). It would be perfectly
correct semantics to let any signal interrupt the string-copying in
execve, i.e. use signal_pending() instead of fatal_signal_pending().
We'll save that change for later, since it could have user-visible
consequences, such as having a timer set too quickly make it so that
an execve can never complete, though it always happened to work before.
Signed-off-by: Roland McGrath <roland@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds a preemption point during the copying of the argument and
environment strings for execve, in copy_strings(). There is already
a preemption point in the count() loop, so this doesn't add any new
points in the abstract sense.
When the total argument+environment strings are very large, the time
spent copying them can be much more than a normal user time slice.
So this change improves the interactivity of the rest of the system
when one process is doing an execve with very large arguments.
Signed-off-by: Roland McGrath <roland@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The CONFIG_STACK_GROWSDOWN variant of setup_arg_pages() does not
check the size of the argument/environment area on the stack.
When it is unworkably large, shift_arg_pages() hits its BUG_ON.
This is exploitable with a very large RLIMIT_STACK limit, to
create a crash pretty easily.
Check that the initial stack is not too large to make it possible
to map in any executable. We're not checking that the actual
executable (or intepreter, for binfmt_elf) will fit. So those
mappings might clobber part of the initial stack mapping. But
that is just userland lossage that userland made happen, not a
kernel problem.
Signed-off-by: Roland McGrath <roland@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
fs: brlock vfsmount_lock
fs: scale files_lock
lglock: introduce special lglock and brlock spin locks
tty: fix fu_list abuse
fs: cleanup files_lock locking
fs: remove extra lookup in __lookup_hash
fs: fs_struct rwlock to spinlock
apparmor: use task path helpers
fs: dentry allocation consolidation
fs: fix do_lookup false negative
mbcache: Limit the maximum number of cache entries
hostfs ->follow_link() braino
hostfs: dumb (and usually harmless) tpyo - strncpy instead of strlcpy
remove SWRITE* I/O types
kill BH_Ordered flag
vfs: update ctime when changing the file's permission by setfacl
cramfs: only unlock new inodes
fix reiserfs_evict_inode end_writeback second call
fs: fs_struct rwlock to spinlock
struct fs_struct.lock is an rwlock with the read-side used to protect root and
pwd members while taking references to them. Taking a reference to a path
typically requires just 2 atomic ops, so the critical section is very small.
Parallel read-side operations would have cacheline contention on the lock, the
dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a
real parallelism increase.
Replace it with a spinlock to avoid one or two atomic operations in typical
path lookup fastpath.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make do_execve() take a const filename pointer so that kernel_execve() compiles
correctly on ARM:
arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type
This also requires the argv and envp arguments to be consted twice, once for
the pointer array and once for the strings the array points to. This is
because do_execve() passes a pointer to the filename (now const) to
copy_strings_kernel(). A simpler alternative would be to cast the filename
pointer in do_execve() when it's passed to copy_strings_kernel().
do_execve() may not change any of the strings it is passed as part of the argv
or envp lists as they are some of them in .rodata, so marking these strings as
const should be fine.
Further kernel_execve() and sys_execve() need to be changed to match.
This has been test built on x86_64, frv, arm and mips.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.infradead.org/users/eparis/notify: (132 commits)
fanotify: use both marks when possible
fsnotify: pass both the vfsmount mark and inode mark
fsnotify: walk the inode and vfsmount lists simultaneously
fsnotify: rework ignored mark flushing
fsnotify: remove global fsnotify groups lists
fsnotify: remove group->mask
fsnotify: remove the global masks
fsnotify: cleanup should_send_event
fanotify: use the mark in handler functions
audit: use the mark in handler functions
dnotify: use the mark in handler functions
inotify: use the mark in handler functions
fsnotify: send fsnotify_mark to groups in event handling functions
fsnotify: Exchange list heads instead of moving elements
fsnotify: srcu to protect read side of inode and vfsmount locks
fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called
fsnotify: use _rcu functions for mark list traversal
fsnotify: place marks on object in order of group memory address
vfs/fsnotify: fsnotify_close can delay the final work in fput
fsnotify: store struct file not struct path
...
Fix up trivial delete/modify conflict in fs/notify/inotify/inotify.c.
* 'bkl/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing:
do_coredump: Do not take BKL
init: Remove the BKL from startup code
fanotify, the upcoming notification system actually needs a struct path so it can
do opens in the context of listeners, and it needs a file so it can get f_flags
from the original process. Close was the only operation that already was passing
a struct file to the notification hook. This patch passes a file for access,
modify, and open as well as they are easily available to these hooks.
Signed-off-by: Eric Paris <eparis@redhat.com>
core_pattern is not actually protected and hasn't been
ever since we introduced procfs support for sysctl -- a
_long_ time. Don't take it here either.
Also nothing inside do_coredump appears to require bkl
protection.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[ remove smp_lock.h headers ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
de_thread() and __exit_signal() use signal_struct->count/notify_count for
synchronization. We can simplify the code and use ->notify_count only.
Instead of comparing these two counters, we can change de_thread() to set
->notify_count = nr_of_sub_threads, then change __exit_signal() to
dec-and-test this counter and notify group_exit_task.
Note that __exit_signal() checks "notify_count > 0" just for symmetry with
exit_notify(), we could just check it is != 0.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- kill "int dump_count", argv_split(argcp) accepts argcp == NULL.
- move "int dump_count" under " if (ispipe)" branch, fail_dropcount
can check ispipe.
- move "char **helper_argv" as well, change the code to do argv_free()
right after call_usermodehelper_fns().
- If call_usermodehelper_fns() fails goto close_fail label instead
of closing the file by hand.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The first patch in this series introduced an init function to the
call_usermodehelper api so that processes could be customized by caller.
This patch takes advantage of that fact, by customizing the helper in
do_coredump to create the pipe and set its core limit to one (for our
recusrsion check). This lets us clean up the previous uglyness in the
usermodehelper internals and factor call_usermodehelper out entirely.
While I'm at it, we can also modify the helper setup to look for a core
limit value of 1 rather than zero for our recursion check
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Page migration requires rmap to be able to find all ptes mapping a page
at all times, otherwise the migration entry can be instantiated, but it
is possible to leave one behind if the second rmap_walk fails to find
the page. If this page is later faulted, migration_entry_to_page() will
call BUG because the page is locked indicating the page was migrated by
the migration PTE not cleaned up. For example
kernel BUG at include/linux/swapops.h:105!
invalid opcode: 0000 [#1] PREEMPT SMP
...
Call Trace:
[<ffffffff810e951a>] handle_mm_fault+0x3f8/0x76a
[<ffffffff8130c7a2>] do_page_fault+0x44a/0x46e
[<ffffffff813099b5>] page_fault+0x25/0x30
[<ffffffff8114de33>] load_elf_binary+0x152a/0x192b
[<ffffffff8111329b>] search_binary_handler+0x173/0x313
[<ffffffff81114896>] do_execve+0x219/0x30a
[<ffffffff8100a5c6>] sys_execve+0x43/0x5e
[<ffffffff8100320a>] stub_execve+0x6a/0xc0
RIP [<ffffffff811094ff>] migration_entry_wait+0xc1/0x129
There is a race between shift_arg_pages and migration that triggers this
bug. A temporary stack is setup during exec and later moved. If
migration moves a page in the temporary stack and the VMA is then removed
before migration completes, the migration PTE may not be found leading to
a BUG when the stack is faulted.
This patch causes pages within the temporary stack during exec to be
skipped by migration. It does this by marking the VMA covering the
temporary stack with an otherwise impossible combination of VMA flags.
These flags are cleared when the temporary stack is moved to its final
location.
[kamezawa.hiroyu@jp.fujitsu.com: idea for having migration skip temporary stacks]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Originally, commit d899bf7b ("procfs: provide stack information for
threads") attempted to introduce a new feature for showing where the
threadstack was located and how many pages are being utilized by the
stack.
Commit c44972f1 ("procfs: disable per-task stack usage on NOMMU") was
applied to fix the NO_MMU case.
Commit 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on
64-bit") was applied to fix a bug in ia32 executables being loaded.
Commit 9ebd4eba7 ("procfs: fix /proc/<pid>/stat stack pointer for kernel
threads") was applied to fix a bug which had kernel threads printing a
userland stack address.
Commit 1306d603f ('proc: partially revert "procfs: provide stack
information for threads"') was then applied to revert the stack pages
being used to solve a significant performance regression.
This patch nearly undoes the effect of all these patches.
The reason for reverting these is it provides an unusable value in
field 28. For x86_64, a fork will result in the task->stack_start
value being updated to the current user top of stack and not the stack
start address. This unpredictability of the stack_start value makes
it worthless. That includes the intended use of showing how much stack
space a thread has.
Other architectures will get different values. As an example, ia64
gets 0. The do_fork() and copy_process() functions appear to treat the
stack_start and stack_size parameters as architecture specific.
I only partially reverted c44972f1 ("procfs: disable per-task stack usage
on NOMMU") . If I had completely reverted it, I would have had to change
mm/Makefile only build pagewalk.o when CONFIG_PROC_PAGE_MONITOR is
configured. Since I could not test the builds without significant effort,
I decided to not change mm/Makefile.
I only partially reverted 89240ba0 ("x86, fs: Fix x86 procfs stack
information for threads on 64-bit") . I left the KSTK_ESP() change in
place as that seemed worthwhile.
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
