linux-toradex.git/kernel, branch v3.3.3

futex: Do not leak robust list to unprivileged process

2012-04-22T22:39:18+00:00

commit bdbb776f882f5ad431aa1e694c69c1c3d6a4a5b8 upstream.

It was possible to extract the robust list head address from a setuid
process if it had used set_robust_list(), allowing an ASLR info leak. This
changes the permission checks to be the same as those used for similar
info that comes out of /proc.

Running a setuid program that uses robust futexes would have had:
  cred->euid != pcred->euid
  cred->euid == pcred->uid
so the old permissions check would allow it. I'm not aware of any setuid
programs that use robust futexes, so this is just a preventative measure.

(This patch is based on changes from grsecurity.)

Signed-off-by: Kees Cook 
Cc: Darren Hart 
Cc: Peter Zijlstra 
Cc: Jiri Kosina 
Cc: Eric W. Biederman 
Cc: David Howells 
Cc: Serge E. Hallyn 
Cc: kernel-hardening@lists.openwall.com
Cc: spender@grsecurity.net
Link: http://lkml.kernel.org/r/20120319231253.GA20893@www.outflux.net
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

nohz: Fix stale jiffies update in tick_nohz_restart()

2012-04-22T22:38:59+00:00

commit 6f103929f8979d2638e58d7f7fda0beefcb8ee7e upstream.

Fix tick_nohz_restart() to not use a stale ktime_t "now" value when
calling tick_do_update_jiffies64(now).

If we reach this point in the loop it means that we crossed a tick
boundary since we grabbed the "now" timestamp, so at this point "now"
refers to a time in the old jiffy, so using the old value for "now" is
incorrect, and is likely to give us a stale jiffies value.

In particular, the first time through the loop the
tick_do_update_jiffies64(now) call is always a no-op, since the
caller, tick_nohz_restart_sched_tick(), will have already called
tick_do_update_jiffies64(now) with that "now" value.

Note that tick_nohz_stop_sched_tick() already uses the correct
approach: when we notice we cross a jiffy boundary, grab a new
timestamp with ktime_get(), and *then* update jiffies.

Signed-off-by: Neal Cardwell 
Cc: Ben Segall 
Cc: Ingo Molnar 
Link: http://lkml.kernel.org/r/1332875377-23014-1-git-send-email-ncardwell@google.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

panic: fix stack dump print on direct call to panic()

2012-04-22T22:38:56+00:00

commit 026ee1f66aaa7f01b617a0ba89ac4b531f9603f1 upstream.

Commit 6e6f0a1f0fa6 ("panic: don't print redundant backtraces on oops")
causes a regression where no stack trace will be printed at all for the
case where kernel code calls panic() directly while not processing an
oops, and of course there are 100's of instances of this type of call.

The original commit executed the check (!oops_in_progress), but this will
always be false because just before the dump_stack() there is a call to
bust_spinlocks(1), which does the following:

  void __attribute__((weak)) bust_spinlocks(int yes)
  {
	if (yes) {
		++oops_in_progress;

The proper way to resolve the problem that original commit tried to
solve is to avoid printing a stack dump from panic() when the either of
the following conditions is true:

  1) TAINT_DIE has been set (this is done by oops_end())
     This indicates and oops has already been printed.
  2) oops_in_progress > 1
     This guards against the rare case where panic() is invoked
     a second time, or in between oops_begin() and oops_end()

Signed-off-by: Jason Wessel 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

cred: copy_process() should clear child->replacement_session_keyring

2012-04-13T16:13:57+00:00

commit 79549c6dfda0603dba9a70a53467ce62d9335c33 upstream.

keyctl_session_to_parent(task) sets ->replacement_session_keyring,
it should be processed and cleared by key_replace_session_keyring().

However, this task can fork before it notices TIF_NOTIFY_RESUME and
the new child gets the bogus ->replacement_session_keyring copied by
dup_task_struct(). This is obviously wrong and, if nothing else, this
leads to put_cred(already_freed_cred).

change copy_creds() to clear this member. If copy_process() fails
before this point the wrong ->replacement_session_keyring doesn't
matter, exit_creds() won't be called.

Signed-off-by: Oleg Nesterov 
Acked-by: David Howells 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

sysctl: fix write access to dmesg_restrict/kptr_restrict

2012-04-13T16:13:55+00:00

commit 620f6e8e855d6d447688a5f67a4e176944a084e8 upstream.

Commit bfdc0b4 adds code to restrict access to dmesg_restrict,
however, it incorrectly alters kptr_restrict rather than
dmesg_restrict.

The original patch from Richard Weinberger
(https://lkml.org/lkml/2011/3/14/362) alters dmesg_restrict as
expected, and so the patch seems to have been misapplied.

This adds the CAP_SYS_ADMIN check to both dmesg_restrict and
kptr_restrict, since both are sensitive.

Reported-by: Phillip Lougher 
Signed-off-by: Kees Cook 
Acked-by: Serge Hallyn 
Acked-by: Richard Weinberger 
Signed-off-by: James Morris 
Signed-off-by: Greg Kroah-Hartman

kgdb,debug_core: pass the breakpoint struct instead of address and memory

2012-04-13T16:13:54+00:00

commit 98b54aa1a2241b59372468bd1e9c2d207bdba54b upstream.

There is extra state information that needs to be exposed in the
kgdb_bpt structure for tracking how a breakpoint was installed.  The
debug_core only uses the the probe_kernel_write() to install
breakpoints, but this is not enough for all the archs.  Some arch such
as x86 need to use text_poke() in order to install a breakpoint into a
read only page.

Passing the kgdb_bpt structure to kgdb_arch_set_breakpoint() and
kgdb_arch_remove_breakpoint() allows other archs to set the type
variable which indicates how the breakpoint was installed.

Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

PM / Sleep: Mitigate race between the freezer and request_firmware()

2012-04-13T16:13:54+00:00

commit 247bc03742545fec2f79939a3b9f738392a0f7b4 upstream.

There is a race condition between the freezer and request_firmware()
such that if request_firmware() is run on one CPU and
freeze_processes() is run on another CPU and usermodehelper_disable()
called by it succeeds to grab umhelper_sem for writing before
usermodehelper_read_trylock() called from request_firmware()
acquires it for reading, the request_firmware() will fail and
trigger a WARN_ON() complaining that it was called at a wrong time.
However, in fact, it wasn't called at a wrong time and
freeze_processes() simply happened to be executed simultaneously.

To avoid this race, at least in some cases, modify
usermodehelper_read_trylock() so that it doesn't fail if the
freezing of tasks has just started and hasn't been completed yet.
Instead, during the freezing of tasks, it will try to freeze the
task that has called it so that it can wait until user space is
thawed without triggering the scary warning.

For this purpose, change usermodehelper_disabled so that it can
take three different values, UMH_ENABLED (0), UMH_FREEZING and
UMH_DISABLED.  The first one means that usermode helpers are
enabled, the last one means "hard disable" (i.e. the system is not
ready for usermode helpers to be used) and the second one
is reserved for the freezer.  Namely, when freeze_processes() is
started, it sets usermodehelper_disabled to UMH_FREEZING which
tells usermodehelper_read_trylock() that it shouldn't fail just
yet and should call try_to_freeze() if woken up and cannot
return immediately.  This way all freezable tasks that happen
to call request_firmware() right before freeze_processes() is
started and lose the race for umhelper_sem with it will be
frozen and will sleep until thaw_processes() unsets
usermodehelper_disabled.  [For the non-freezable callers of
request_firmware() the race for umhelper_sem against
freeze_processes() is unfortunately unavoidable.]

Reported-by: Stephen Boyd 
Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

PM / Sleep: Move disabling of usermode helpers to the freezer

2012-04-13T16:13:54+00:00

commit 1e73203cd1157a03facc41ffb54050f5b28e55bd upstream.

The core suspend/hibernation code calls usermodehelper_disable() to
avoid race conditions between the freezer and the starting of
usermode helpers and each code path has to do that on its own.
However, it is always called right before freeze_processes()
and usermodehelper_enable() is always called right after
thaw_processes().  For this reason, to avoid code duplication and
to make the connection between usermodehelper_disable() and the
freezer more visible, make freeze_processes() call it and remove the
direct usermodehelper_disable() and usermodehelper_enable() calls
from all suspend/hibernation code paths.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

PM / Hibernate: Disable usermode helpers right before freezing tasks

2012-04-13T16:13:54+00:00

commit 7b5179ac14dbad945647ac9e76bbbf14ed9e0dbe upstream.

There is no reason to call usermodehelper_disable() before creating
memory bitmaps in hibernate() and software_resume(), so call it right
before freeze_processes(), in accordance with the other suspend and
hibernation code.  Consequently, call usermodehelper_enable() right
after the thawing of tasks rather than after freeing the memory
bitmaps.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

firmware_class: Do not warn that system is not ready from async loads

2012-04-13T16:13:53+00:00

commit 9b78c1da60b3c62ccdd1509f0902ad19ceaf776b upstream.

If firmware is requested asynchronously, by calling
request_firmware_nowait(), there is no reason to fail the request
(and warn the user) when the system is (presumably temporarily)
unready to handle it (because user space is not available yet or
frozen).  For this reason, introduce an alternative routine for
read-locking umhelper_sem, usermodehelper_read_lock_wait(), that
will wait for usermodehelper_disabled to be unset (possibly with
a timeout) and make request_firmware_work_func() use it instead of
usermodehelper_read_trylock().

Accordingly, modify request_firmware() so that it uses
usermodehelper_read_trylock() to acquire umhelper_sem and remove
the code related to that lock from _request_firmware().

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman