Carlos O'Donell [Fri, 19 Jul 2013 06:42:03 +0000 (02:42 -0400)]
CVE-2013-2207, BZ #15755: Disable pt_chown.
The helper binary pt_chown tricked into granting access to another
user's pseudo-terminal.
Pre-conditions for the attack:
* Attacker with local user account
* Kernel with FUSE support
* "user_allow_other" in /etc/fuse.conf
* Victim with allocated slave in /dev/pts
Using the setuid installed pt_chown and a weak check on whether a file
descriptor is a tty, an attacker could fake a pty check using FUSE and
trick pt_chown to grant ownership of a pty descriptor that the current
user does not own. It cannot access /dev/pts/ptmx however.
In most modern distributions pt_chown is not needed because devpts
is enabled by default. The fix for this CVE is to disable building
and using pt_chown by default. We still provide a configure option
to enable hte use of pt_chown but distributions do so at their own
risk.
Carlos O'Donell [Tue, 16 Jul 2013 21:55:43 +0000 (17:55 -0400)]
BZ #15711: Avoid circular dependency for syscall.h
The generated header is compiled with `-ffreestanding' to avoid any
circular dependencies against the installed implementation headers.
Such a dependency would require the implementation header to be
installed before the generated header could be built (See bug 15711).
In current practice the generated header dependencies do not include
any of the implementation headers removed by the use of `-ffreestanding'.
---
2013-07-15 Carlos O'Donell <carlos@redhat.com>
[BZ #15711]
* sysdeps/unix/sysv/linux/Makefile ($(objpfx)bits/syscall%h):
Avoid system header dependency with -ffreestanding.
($(objpfx)bits/syscall%d): Likewise.
Chris Metcalf [Wed, 3 Jul 2013 18:48:39 +0000 (14:48 -0400)]
tile: use _dl_static_init to set GLRO(gl_pagesize)
A recently-added test (dlfcn/tststatic5) pointed out that tile was not
properly initializing the variable pagesize in certain cases. This
change just copies the existing code from MIPS.
Chris Metcalf [Wed, 3 Jul 2013 15:23:01 +0000 (11:23 -0400)]
tile: use soft-fp for fma() and fmaf()
The sfp-machine.h is based on the gcc version, but extended with
required new macros by comparison with other architectures and by
investigating the hardware support for FP on tile.
Andi Kleen [Thu, 27 Jun 2013 18:15:06 +0000 (11:15 -0700)]
Disable elision for any pthread_mutexattr_settype call
PTHREAD_MUTEX_NORMAL requires deadlock for nesting, DEFAULT
does not. Since glibc uses the same value (0) disable elision
for any call to pthread_mutexattr_settype() with a 0 value.
This implies that a program can disable elision by doing
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL)
Andi Kleen [Sat, 22 Dec 2012 09:03:04 +0000 (01:03 -0800)]
Add elision to pthread_mutex_{try,timed,un}lock
Add elision paths to the basic mutex locks.
The normal path has a check for RTM and upgrades the lock
to RTM when available. Trylocks cannot automatically upgrade,
so they check for elision every time.
We use a 4 byte value in the mutex to store the lock
elision adaptation state. This is separate from the adaptive
spin state and uses a separate field.
Condition variables currently do not support elision.
Recursive mutexes and condition variables may be supported at some point,
but are not in the current implementation. Also "trylock" will
not automatically enable elision unless some other lock call
has been already called on the lock.
This version does not use IFUNC, so it means every lock has one
additional check for elision. Benchmarking showed the overhead
to be negligible.
Andi Kleen [Fri, 28 Jun 2013 12:19:37 +0000 (05:19 -0700)]
Add minimal test suite changes for elision enabled kernels
tst-mutex5 and 8 test some behaviour not required by POSIX,
that elision changes. This changes these tests to not check
this when elision is enabled at configure time.
Andi Kleen [Sat, 10 Nov 2012 08:51:26 +0000 (00:51 -0800)]
Add the low level infrastructure for pthreads lock elision with TSX
Lock elision using TSX is a technique to optimize lock scaling
It allows to run locks in parallel using hardware support for
a transactional execution mode in 4th generation Intel Core CPUs.
See http://www.intel.com/software/tsx for more Information.
This patch implements a simple adaptive lock elision algorithm based
on RTM. It enables elision for the pthread mutexes and rwlocks.
The algorithm keeps track whether a mutex successfully elides or not,
and stops eliding for some time when it is not.
When the CPU supports RTM the elision path is automatically tried,
otherwise any elision is disabled.
The adaptation algorithm and its tuning is currently preliminary.
The code adds some checks to the lock fast paths. Micro-benchmarks
show little to no difference without RTM.
This patch implements the low level "lll_" code for lock elision.
Followon patches hook this into the pthread implementation
Changes with the RTM mutexes:
-----------------------------
Lock elision in pthreads is generally compatible with existing programs.
There are some obscure exceptions, which are expected to be uncommon.
See the manual for more details.
- A broken program that unlocks a free lock will crash.
There are ways around this with some tradeoffs (more code in hot paths)
I'm still undecided on what approach to take here; have to wait for testing reports.
- pthread_mutex_destroy of a lock mutex will not return EBUSY but 0.
- There's also a similar situation with trylock outside the mutex,
"knowing" that the mutex must be held due to some other condition.
In this case an assert failure cannot be recovered. This situation is
usually an existing bug in the program.
- Same applies to the rwlocks. Some of the return values changes
(for example there is no EDEADLK for an elided lock, unless it aborts.
However when elided it will also never deadlock of course)
- Timing changes, so broken programs that make assumptions about specific timing
may expose already existing latent problems. Note that these broken programs will
break in other situations too (loaded system, new faster hardware, compiler
optimizations etc.)
- Programs with non recursive mutexes that take them recursively in a thread and
which would always deadlock without elision may not always see a deadlock.
The deadlock will only happen on an early or delayed abort (which typically
happens at some point)
This only happens for mutexes not explicitely set to PTHREAD_MUTEX_NORMAL
or PTHREAD_MUTEX_ADAPTIVE_NP. PTHREAD_MUTEX_NORMAL mutexes do not elide.
The elision default can be set at configure time.
This patch implements the basic infrastructure for elision.
[BZ #15022] Correct global-scope dlopen issues in static executables.
This change creates a link map in static executables to serve as the
global search list for dlopen. It fixes a problem with the inability
to access the global symbol object and a crash on an attempt to map a
DSO into the global scope. Some code that has become dead after the
addition of this link map is removed too and test cases are provided.
This function is now called from dl_open_worker with the GL(dl_load_lock)
lock held and no longer needs local protection. GL(dl_load_lock) also
correctly protects _dl_lookup_symbol_x called here that relies on the
caller to have serialized access to the data structures it uses.
Static applications that call pthread_exit on the main
thread segfault. This is because after a thread terminates
__libc_start_main decrements __nptl_nthreads which is only
defined in pthread_create. Therefore the right solution is
to add a requirement to pthread_create from pthread_exit.
~~~
nptl/
2013-06-24 Vladimir Nikulichev <v.nikulichev@gmail.com>
[BZ #12310]
* pthread_exit.c: Add reference to pthread_create.
Check wheter the compiler has the option -fno-tree-loop-distribute-patterns
to inhibit loop transformation to library calls and uses it on memset
and memmove default implementation to avoid recursive calls.
git://sourceware.org / glibc.git / log