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  1. 18 Dec, 2018 3 commits
    • Thomas Gleixner's avatar
      futex: Cure exit race · da791a66
      Thomas Gleixner authored 
      Stefan reported, that the glibc tst-robustpi4 test case fails
occasionally. That case creates the following race between
sys_exit() and sys_futex_lock_pi():

 CPU0				CPU1

 sys_exit()			sys_futex()
  do_exit()			 futex_lock_pi()
   exit_signals(tsk)		  No waiters:
    tsk->flags |= PF_EXITING;	  *uaddr == 0x00000PID
  mm_release(tsk)		  Set waiter bit
   exit_robust_list(tsk) {	  *uaddr = 0x80000PID;
      Set owner died		  attach_to_pi_owner() {
    *uaddr = 0xC0000000;	   tsk = get_task(PID);
   }				   if (!tsk->flags & PF_EXITING) {
  ...				     attach();
  tsk->flags |= PF_EXITPIDONE;	   } else {
				     if (!(tsk->flags & PF_EXITPIDONE))
				       return -EAGAIN;
				     return -ESRCH; <--- FAIL
				   }

ESRCH is returned all the way to user space, which triggers the glibc test
case assert. Returning ESRCH unconditionally is wrong here because the user
space value has been changed by the exiting task to 0xC0000000, i.e. the
FUTEX_OWNER_DIED bit is set and the futex PID value has been cleared. This
is a valid state and the kernel has to handle it, i.e. taking the futex.

Cure it by rereading the user space value when PF_EXITING and PF_EXITPIDONE
is set in the task which 'owns' the futex. If the value has changed, let
the kernel retry the operation, which includes all regular sanity checks
and correctly handles the FUTEX_OWNER_DIED case.

If it hasn't changed, then return ESRCH as there is no way to distinguish
this case from malfunctioning user space. This happens when the exiting
task did not have a robust list, the robust list was corrupted or the user
space value in the futex was simply bogus.
Reported-by: default avatarStefan Liebler <stli@linux.ibm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=200467
Link: https://lkml.kernel.org/r/20181210152311.986181245@linutronix.de
      da791a66
    • Mimi Zohar's avatar
      ima: cleanup the match_token policy code · 1a9430db
      Mimi Zohar authored 
      Start the policy_tokens and the associated enumeration from zero,
simplifying the pt macro.
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1a9430db
    • Linus Torvalds's avatar
      security: don't use a negative Opt_err token index · 94c13f66
      Linus Torvalds authored 
      The code uses a bitmap to check for duplicate tokens during parsing, and
that doesn't work at all for the negative Opt_err token case.

There is absolutely no reason to make Opt_err be negative, and in fact
it only confuses things, since some of the affected functions actually
return a positive Opt_xyz enum _or_ a regular negative error code (eg
-EINVAL), and using -1 for Opt_err makes no sense.

There are similar problems in ima_policy.c and key encryption, but they
don't have the immediate bug wrt bitmap handing, and ima_policy.c in
particular needs a different patch to make the enum values match the
token array index.  Mimi is sending that separately.

Reported-by: syzbot+a22e0dc07567662c50bc@syzkaller.appspotmail.com
Reported-by: default avatarEric Biggers <ebiggers@kernel.org>
Fixes: 5208cc83 ("keys, trusted: fix: *do not* allow duplicate key options")
Fixes: 00d60fd3 ("KEYS: Provide keyctls to drive the new key type ops for asymmetric keys [ver #2]")
Cc: James Morris James Morris <jmorris@namei.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      94c13f66
  3. 16 Dec, 2018 1 commit
  5. 14 Dec, 2018 20 commits
  7. 13 Dec, 2018 13 commits
  9. 12 Dec, 2018 3 commits
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