coredump: kill call_count, add core_name_size

Imho, "atomic_t call_count" is ugly and should die. It buys nothing and
in fact it can grow more than necessary, expand doesn't check if it was
already

coredump: kill call_count, add core_name_size

Imho, "atomic_t call_count" is ugly and should die. It buys nothing and
in fact it can grow more than necessary, expand doesn't check if it was
already incremented by another task.

Kill it, and introduce "static int core_name_size" updated by
expand_corename(). This is obviously racy too but harmless, and
core_name_size never grows for no reason.

We do not bother to to calculate the "right" new size, we simply do
kmalloc(size_we_need) and use ksize() to rely on kmalloc_index's decision.

Finally change format_corename() to use expand_corename(), krealloc(NULL)
is fine.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: kill cn_escape(), introduce cn_esc_printf()

The usage of cn_escape() looks really annoying, imho this sequence needs a
wrapper. And it is buggy. If cn_printf() does expand_corename()
cn_

coredump: kill cn_escape(), introduce cn_esc_printf()

The usage of cn_escape() looks really annoying, imho this sequence needs a
wrapper. And it is buggy. If cn_printf() does expand_corename()
cn_escape() writes to the freed memory.

Introduce cn_esc_printf() which hopefully does this all right. It records
the index before cn_vprintf(), not "char *" which is no longer valid (in
general) after krealloc().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: cn_vprintf() has no reason to call vsnprintf() twice

cn_vprintf() looks really overcomplicated and sub-optimal. We do not need
vsnprintf(NULL) to calculate the size we need, we can simply

coredump: cn_vprintf() has no reason to call vsnprintf() twice

cn_vprintf() looks really overcomplicated and sub-optimal. We do not need
vsnprintf(NULL) to calculate the size we need, we can simply try to print
into the current buffer and expand/retry only if necessary.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: introduce cn_vprintf()

Turn cn_printf(...) into cn_vprintf(va_list args), reintroduce
cn_printf() as a trivial wrapper.

This simplifies the next change and cn_vprintf() will have more
cal

coredump: introduce cn_vprintf()

Turn cn_printf(...) into cn_vprintf(va_list args), reintroduce
cn_printf() as a trivial wrapper.

This simplifies the next change and cn_vprintf() will have more
callers.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: format_corename() can leak cn->corename

do_coredump() assumes that format_corename() can only fail if
expand_corename() fails and frees cn->corename. This is not true, for
example cn_prin

coredump: format_corename() can leak cn->corename

do_coredump() assumes that format_corename() can only fail if
expand_corename() fails and frees cn->corename. This is not true, for
example cn_print_exe_file() can fail and in this case nobody frees
cn->corename.

Change do_coredump() to always do kfree(cn->corename) after it calls
format_corename() (NULL is fine), change expand_corename() to do nothing
if kmalloc() fails.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Colin Walters <walters@verbum.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Lennart Poettering <mzxreary@0pointer.de>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

do_coredump(): don't wait for thaw if coredump has already been interrupted

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

coredump: change wait_for_dump_helpers() to use wait_event_interruptible()

wait_for_dump_helpers() calls wake_up/kill_fasync from inside the
wait_event-like loop. This is not needed and in fact thi

coredump: change wait_for_dump_helpers() to use wait_event_interruptible()

wait_for_dump_helpers() calls wake_up/kill_fasync from inside the
wait_event-like loop. This is not needed and in fact this is not
strictly correct, we can/should do this only once after we change
pipe->writers. We could even check if it becomes zero.

Change this code to use use wait_event_interruptible(), this can also
help to make this wait freezable.

With this patch we check pipe->readers without pipe_lock(), this is
fine. Once we see pipe->readers == 1 we know that the handler
decremented the counter, this is all we need.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: factor out the setting of PF_DUMPCORE

Cleanup. Every linux_binfmt->core_dump() sets PF_DUMPCORE, move this into
zap_threads() called by do_coredump().

Signed-off-by: Oleg Nesterov <oleg@

coredump: factor out the setting of PF_DUMPCORE

Cleanup. Every linux_binfmt->core_dump() sets PF_DUMPCORE, move this into
zap_threads() called by do_coredump().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: introduce dump_interrupted()

By discussion with Mandeep.

Change dump_write(), dump_seek() and do_coredump() to check
signal_pending() and abort if it is true. dump_seek() does this only

coredump: introduce dump_interrupted()

By discussion with Mandeep.

Change dump_write(), dump_seek() and do_coredump() to check
signal_pending() and abort if it is true. dump_seek() does this only
before f_op->llseek(), otherwise it relies on dump_write().

We need this change to ensure that the coredump won't delay suspend, and
to ensure it reacts to SIGKILL "quickly enough", a core dump can take a
lot of time. In particular this can help oom-killer.

We add the new trivial helper, dump_interrupted() to add the comments and
to simplify the potential freezer changes. Perhaps it will have more
callers.

Ideally it should do try_to_freeze() but then we need the unpleasant
changes in dump_write() and wait_for_dump_helpers(). It is not trivial to
change dump_write() to restart if f_op->write() fails because of
freezing(). We need to handle the short writes, we need to clear
TIF_SIGPENDING (and we can't rely on recalc_sigpending() unless we change
it to check PF_DUMPCORE). And if the buggy f_op->write() sets
TIF_SIGPENDING we can not distinguish this case from the race with
freeze_task() + __thaw_task().

So we simply accept the fact that the freezer can truncate a core-dump but
at least you can reliably suspend. Hopefully we can tolerate this
unlikely case and the necessary complications doesn't worth a trouble.
But if we decide to make the coredumping freezable later we can do this on
top of this change.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: sanitize the setting of signal->group_exit_code

Now that the coredumping process can be SIGKILL'ed, the setting of
->group_exit_code in do_coredump() can race with complete_signal() and
SI

coredump: sanitize the setting of signal->group_exit_code

Now that the coredumping process can be SIGKILL'ed, the setting of
->group_exit_code in do_coredump() can race with complete_signal() and
SIGKILL or 0x80 can be "lost", or wait(status) can report status ==
SIGKILL | 0x80.

But the main problem is that it is not clear to me what should we do if
binfmt->core_dump() succeeds but SIGKILL was sent, that is why this patch
comes as a separate change.

This patch adds 0x80 if ->core_dump() succeeds and the process was not
killed. But perhaps we can (should?) re-set ->group_exit_code changed by
SIGKILL back to "siginfo->si_signo |= 0x80" in case when core_dumped == T.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
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>

show more ...

coredump: ensure that SIGKILL always kills the dumping thread

prepare_signal() blesses SIGKILL sent to the dumping process but this
signal can be "lost" anyway. The problems is, complete_signal() s

coredump: ensure that SIGKILL always kills the dumping thread

prepare_signal() blesses SIGKILL sent to the dumping process but this
signal can be "lost" anyway. The problems is, complete_signal() sees
SIGNAL_GROUP_EXIT and skips the "kill them all" logic. And even if the
dumping process is single-threaded (so the target is always "correct"),
the group-wide SIGKILL is not recorded in task->pending and thus
__fatal_signal_pending() won't be true. A multi-threaded case has even
more problems.

And even ignoring all technical details, SIGNAL_GROUP_EXIT doesn't look
right to me. This coredumping process is not exiting yet, it can do a lot
of work dumping the core.

With this patch the dumping process doesn't have SIGNAL_GROUP_EXIT, we set
signal->group_exit_task instead. This makes signal_group_exit() true and
thus this should equally close the races with exit/exec/stop but allows to
kill the dumping thread reliably.

Notes:
- It is not clear what should we do with ->group_exit_code
if the dumper was killed, see the next change.

- we need more (hopefully straightforward) changes to ensure
that SIGKILL actually interrupts the coredump. Basically we
need to check __fatal_signal_pending() in dump_write() and
dump_seek().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
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>

show more ...

coredump: only SIGKILL should interrupt the coredumping task

There are 2 well known and ancient problems with coredump/signals, and a
lot of related bug reports:

- do_coredump() clears TIF_SIGPENDI

coredump: only SIGKILL should interrupt the coredumping task

There are 2 well known and ancient problems with coredump/signals, and a
lot of related bug reports:

- do_coredump() clears TIF_SIGPENDING but of course this can't help
if, say, SIGCHLD comes after that.

In this case the coredump can fail unexpectedly. See for example
wait_for_dump_helper()->signal_pending() check but there are other
reasons.

- At the same time, dumping a huge core on the slow media can take a
lot of time/resources and there is no way to kill the coredumping
task reliably. In particular this is not oom_kill-friendly.

This patch tries to fix the 1st problem, and makes the preparation for the
next changes.

We add the new SIGNAL_GROUP_COREDUMP flag set by zap_threads() to indicate
that this process dumps the core. prepare_signal() checks this flag and
nacks any signal except SIGKILL.

Note that this check tries to be conservative, in the long term we should
probably treat the SIGNAL_GROUP_EXIT case equally but this needs more
discussion. See marc.info/?l=linux-kernel&m=120508897917439

Notes:
- recalc_sigpending() doesn't check SIGNAL_GROUP_COREDUMP.
The patch assumes that dump_write/etc paths should never
call it, but we can change it as well.

- There is another source of TIF_SIGPENDING, freezer. This
will be addressed separately.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
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>

show more ...

usermodehelper: split remaining calls to call_usermodehelper_fns()

These are the only users of call_usermodehelper_fns(). This function
suffers from not being able to determine if the cleanup is ca

usermodehelper: split remaining calls to call_usermodehelper_fns()

These are the only users of call_usermodehelper_fns(). This function
suffers from not being able to determine if the cleanup is called. Even
if in this places the cleanup pointer is NULL, convert them to use the
separate call_usermodehelper_setup() + call_usermodehelper_exec()
functions so we can remove the _fns variant.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: remove trailling whitespace

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jam

coredump: remove trailling whitespace

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

pipe: set file->private_data to ->i_pipe

simplify get_pipe_info(), while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

lift sb_start_write() out of ->write()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

coredump: remove redundant defines for dumpable states

The existing SUID_DUMP_* defines duplicate the newer SUID_DUMPABLE_*
defines introduced in 54b501992dd2 ("coredump: warn about unsafe
suid_dump

coredump: remove redundant defines for dumpable states

The existing SUID_DUMP_* defines duplicate the newer SUID_DUMPABLE_*
defines introduced in 54b501992dd2 ("coredump: warn about unsafe
suid_dumpable / core_pattern combo"). Remove the new ones, and use the
prior values instead.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Chen Gang <gang.chen@asianux.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alan Cox <alan@linux.intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: James Morris <james.l.morris@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

do_coredump(): get rid of pt_regs argument

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fix a leak in replace_fd() users

replace_fd() began with "eats a reference, tries to insert into
descriptor table" semantics; at some point I'd switched it to
much saner current behaviour ("try to i

fix a leak in replace_fd() users

replace_fd() began with "eats a reference, tries to insert into
descriptor table" semantics; at some point I'd switched it to
much saner current behaviour ("try to insert into descriptor
table, grabbing a new reference if inserted; caller should do
fput() in any case"), but forgot to update the callers.
Mea culpa...

[Spotted by Pavel Roskin, who has really weird system with pipe-fed
coredumps as part of what he considers a normal boot ;-)]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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coredump: pass siginfo_t* to do_coredump() and below, not merely signr

This is a preparatory patch for the introduction of NT_SIGINFO elf note.

With this patch we pass "siginfo_t *siginfo" instead

coredump: pass siginfo_t* to do_coredump() and below, not merely signr

This is a preparatory patch for the introduction of NT_SIGINFO elf note.

With this patch we pass "siginfo_t *siginfo" instead of "int signr" to
do_coredump() and put it into coredump_params. It will be used by the
next patch. Most changes are simple s/signr/siginfo->si_signo/.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Amerigo Wang <amwang@redhat.com>
Cc: "Jonathan M. Foote" <jmfoote@cert.org>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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coredump: add support for %d=__get_dumpable() in core name

Some coredump handlers want to create a core file in a way compatible with
standard behavior. Standard behavior with fs.suid_dumpable = 2

coredump: add support for %d=__get_dumpable() in core name

Some coredump handlers want to create a core file in a way compatible with
standard behavior. Standard behavior with fs.suid_dumpable = 2 is to
create core file with uid=gid=0. However, there was no way for coredump
handler to know that the process being dumped was suid'ed.

This patch adds the new %d specifier for format_corename() which simply
reports __get_dumpable(mm->flags), this is compatible with
/proc/sys/fs/suid_dumpable we already have.

Addresses https://bugzilla.redhat.com/show_bug.cgi?id=787135

Developed during a discussion with Denys Vlasenko.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Alex Kelly <alex.page.kelly@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Cong Wang <amwang@redhat.com>
Cc: Jiri Moskovcak <jmoskovc@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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coredump: update coredump-related headers

Create a new header file, fs/coredump.h, which contains functions only
used by the new coredump.c. It also moves do_coredump to the
include/linux/coredump.

coredump: update coredump-related headers

Create a new header file, fs/coredump.h, which contains functions only
used by the new coredump.c. It also moves do_coredump to the
include/linux/coredump.h header file, for consistency.

Signed-off-by: Alex Kelly <alex.page.kelly@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

show more ...

coredump: move core dump functionality into its own file

This prepares for making core dump functionality optional.

The variable "suid_dumpable" and associated functions are left in fs/exec.c
becau

coredump: move core dump functionality into its own file

This prepares for making core dump functionality optional.

The variable "suid_dumpable" and associated functions are left in fs/exec.c
because they're used elsewhere, such as in ptrace.

Signed-off-by: Alex Kelly <alex.page.kelly@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

show more ...

coredump: fix core_pattern parse error

'format_corename()' will splite 'core_pattern' on spaces when it is in
pipe mode, and take helper_argv[0] as the path to usermode executable.
I

coredump: fix core_pattern parse error

'format_corename()' will splite 'core_pattern' on spaces when it is in
pipe mode, and take helper_argv[0] as the path to usermode executable.
It works fine in most cases.

However, if there is a space between '|' and '/file/path', such as
'| /usr/lib/systemd/systemd-coredump %P %u %g', then helper_argv[0] will
be parsed as '', and users will get a 'Core dump to | disabled'.

It is not friendly to users, as the pattern above was valid previously.
Fix this by ignoring the spaces between '|' and '/file/path'.

Fixes: 315c69261dd3 ("coredump: split pipe command whitespace before expanding template")
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Wise <pabs3@bonedaddy.net>
Cc: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398]
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/5fb62870.1c69fb81.8ef5d.af76@mx.google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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