linux-stable.git/fs/proc, branch linux-2.6.27.y

proc: do proper range check on readdir offset

2011-04-30T14:53:38+00:00

commit d8bdc59f215e62098bc5b4256fd9928bf27053a1 upstream.

Rather than pass in some random truncated offset to the pid-related
functions, check that the offset is in range up-front.

This is just cleanup, the previous commit fixed the real problem.

Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

proc: protect mm start_code/end_code in /proc/pid/stat

2011-04-30T14:53:22+00:00

commit 5883f57ca0008ffc93e09cbb9847a1928e50c6f3 upstream.

While mm->start_stack was protected from cross-uid viewing (commit
f83ce3e6b02d5 ("proc: avoid information leaks to non-privileged
processes")), the start_code and end_code values were not.  This would
allow the text location of a PIE binary to leak, defeating ASLR.

Note that the value "1" is used instead of "0" for a protected value since
"ps", "killall", and likely other readers of /proc/pid/stat, take
start_code of "0" to mean a kernel thread and will misbehave.  Thanks to
Brad Spengler for pointing this out.

Addresses CVE-2011-0726

Signed-off-by: Kees Cook 
Cc: Alexey Dobriyan 
Cc: David Howells 
Cc: Eugene Teo 
Cc: Martin Schwidefsky 
Cc: Brad Spengler 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

procfs: fix /proc//maps heap check

2011-04-30T14:53:21+00:00

commit 0db0c01b53a1a421513f91573241aabafb87802a upstream.

The current code fails to print the "[heap]" marking if the heap is split
into multiple mappings.

Fix the check so that the marking is displayed in all possible cases:
	1. vma matches exactly the heap
	2. the heap vma is merged e.g. with bss
	3. the heap vma is splitted e.g. due to locked pages

Test cases. In all cases, the process should have mapping(s) with
[heap] marking:

	(1) vma matches exactly the heap

	#include 
	#include 
	#include 

	int main (void)
	{
		if (sbrk(4096) != (void *)-1) {
			printf("check /proc/%d/maps\n", (int)getpid());
			while (1)
				sleep(1);
		}
		return 0;
	}

	# ./test1
	check /proc/553/maps
	[1] + Stopped                    ./test1
	# cat /proc/553/maps | head -4
	00008000-00009000 r-xp 00000000 01:00 3113640    /test1
	00010000-00011000 rw-p 00000000 01:00 3113640    /test1
	00011000-00012000 rw-p 00000000 00:00 0          [heap]
	4006f000-40070000 rw-p 00000000 00:00 0

	(2) the heap vma is merged

	#include 
	#include 
	#include 

	char foo[4096] = "foo";
	char bar[4096];

	int main (void)
	{
		if (sbrk(4096) != (void *)-1) {
			printf("check /proc/%d/maps\n", (int)getpid());
			while (1)
				sleep(1);
		}
		return 0;
	}

	# ./test2
	check /proc/556/maps
	[2] + Stopped                    ./test2
	# cat /proc/556/maps | head -4
	00008000-00009000 r-xp 00000000 01:00 3116312    /test2
	00010000-00012000 rw-p 00000000 01:00 3116312    /test2
	00012000-00014000 rw-p 00000000 00:00 0          [heap]
	4004a000-4004b000 rw-p 00000000 00:00 0

	(3) the heap vma is splitted (this fails without the patch)

	#include 
	#include 
	#include 
	#include 

	int main (void)
	{
		if ((sbrk(4096) != (void *)-1) && !mlockall(MCL_FUTURE) &&
		    (sbrk(4096) != (void *)-1)) {
			printf("check /proc/%d/maps\n", (int)getpid());
			while (1)
				sleep(1);
		}
		return 0;
	}

	# ./test3
	check /proc/559/maps
	[1] + Stopped                    ./test3
	# cat /proc/559/maps|head -4
	00008000-00009000 r-xp 00000000 01:00 3119108    /test3
	00010000-00011000 rw-p 00000000 01:00 3119108    /test3
	00011000-00012000 rw-p 00000000 00:00 0          [heap]
	00012000-00013000 rw-p 00000000 00:00 0          [heap]

It looks like the bug has been there forever, and since it only results in
some information missing from a procfile, it does not fulfil the -stable
"critical issue" criteria.

Signed-off-by: Aaro Koskinen 
Reviewed-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

s390: remove task_show_regs

2011-04-30T14:53:06+00:00

commit 261cd298a8c363d7985e3482946edb4bfedacf98 upstream.

task_show_regs used to be a debugging aid in the early bringup days
of Linux on s390. /proc//status is a world readable file, it
is not a good idea to show the registers of a process. The only
correct fix is to remove task_show_regs.

Reported-by: Al Viro 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: fix up some user-visible effects of the stack guard page

2010-08-20T18:25:13+00:00

commit d7824370e26325c881b665350ce64fb0a4fde24a upstream.

This commit makes the stack guard page somewhat less visible to user
space. It does this by:

 - not showing the guard page in /proc//maps

   It looks like lvm-tools will actually read /proc/self/maps to figure
   out where all its mappings are, and effectively do a specialized
   "mlockall()" in user space.  By not showing the guard page as part of
   the mapping (by just adding PAGE_SIZE to the start for grows-up
   pages), lvm-tools ends up not being aware of it.

 - by also teaching the _real_ mlock() functionality not to try to lock
   the guard page.

   That would just expand the mapping down to create a new guard page,
   so there really is no point in trying to lock it in place.

It would perhaps be nice to show the guard page specially in
/proc//maps (or at least mark grow-down segments some way), but
let's not open ourselves up to more breakage by user space from programs
that depends on the exact deails of the 'maps' file.

Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools
source code to see what was going on with the whole new warning.

[Note, for .27, only the /proc change is done, mlock is not modified
here. - gregkh]

Reported-and-tested-by: François Valenduc 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm_for_maps: shift down_read(mmap_sem) to the caller

2009-08-16T21:27:35+00:00

commit 00f89d218523b9bf6b522349c039d5ac80aa536d upstream.

mm_for_maps() takes ->mmap_sem after security checks, this looks
strange and obfuscates the locking rules. Move this lock to its
single caller, m_start().

Signed-off-by: Oleg Nesterov 
Acked-by: Serge Hallyn 
Signed-off-by: James Morris 
Signed-off-by: Greg Kroah-Hartman

mm_for_maps: simplify, use ptrace_may_access()

2009-08-16T21:27:32+00:00

commit 13f0feafa6b8aead57a2a328e2fca6a5828bf286 upstream.

It would be nice to kill __ptrace_may_access(). It requires task_lock(),
but this lock is only needed to read mm->flags in the middle.

Convert mm_for_maps() to use ptrace_may_access(), this also simplifies
the code a little bit.

Also, we do not need to take ->mmap_sem in advance. In fact I think
mm_for_maps() should not play with ->mmap_sem at all, the caller should
take this lock.

With or without this patch, without ->cred_guard_mutex held we can race
with exec() and get the new ->mm but check old creds.

Signed-off-by: Oleg Nesterov 
Reviewed-by: Serge Hallyn 
Signed-off-by: James Morris 
Signed-off-by: Greg Kroah-Hartman

proc: avoid information leaks to non-privileged processes

2009-05-08T21:54:36+00:00

commit f83ce3e6b02d5e48b3a43b001390e2b58820389d upstream.

By using the same test as is used for /proc/pid/maps and /proc/pid/smaps,
only allow processes that can ptrace() a given process to see information
that might be used to bypass address space layout randomization (ASLR).
These include eip, esp, wchan, and start_stack in /proc/pid/stat as well
as the non-symbolic output from /proc/pid/wchan.

ASLR can be bypassed by sampling eip as shown by the proof-of-concept
code at http://code.google.com/p/fuzzyaslr/ As part of a presentation
(http://www.cr0.org/paper/to-jt-linux-alsr-leak.pdf) esp and wchan were
also noted as possibly usable information leaks as well.  The
start_stack address also leaks potentially useful information.

Cc: Stable Team 
Signed-off-by: Jake Edge 
Acked-by: Arjan van de Ven 
Acked-by: "Eric W. Biederman" 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

pagemap: require aligned-length, non-null reads of /proc/pid/pagemap

2009-05-08T21:54:34+00:00

commit 0816178638c15ce5472d39d771a96860dff4141a upstream.

The intention of commit aae8679b0ebcaa92f99c1c3cb0cd651594a43915
("pagemap: fix bug in add_to_pagemap, require aligned-length reads of
/proc/pid/pagemap") was to force reads of /proc/pid/pagemap to be a
multiple of 8 bytes, but now it allows to read 0 bytes, which actually
puts some data to user's buffer.  According to POSIX, if count is zero,
read() should return zero and has no other results.

Signed-off-by: Vitaly Mayatskikh 
Cc: Thomas Tuttle 
Acked-by: Matt Mackall 
Cc: Alexey Dobriyan 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs core fixes

2009-05-02T17:25:00+00:00

Please add the following 4 commits to 2.6.27-stable and 2.6.28-stable.
However, there has been a lot of change here between 2.6.28 and 2.6.29:
in particular, fs/exec.c's unsafe_exec() grew into the more complicated
check_unsafe_exec().  So applying the original patches gives too many
rejects: at the bottom is the diffstat and the combined patch required.

1
Commit: 53e9309e01277ec99c38e84e0ca16921287cf470
Author: Hugh Dickins 
Date: Sat, 28 Mar 2009 23:16:03 +0000 (+0000)
Subject: compat_do_execve should unshare_files

2
Commit: e426b64c412aaa3e9eb3e4b261dc5be0d5a83e78
Author: Hugh Dickins 
Date: Sat, 28 Mar 2009 23:20:19 +0000 (+0000)
Subject: fix setuid sometimes doesn't

3
Commit: 7c2c7d993044cddc5010f6f429b100c63bc7dffb
Author: Hugh Dickins 
Date: Sat, 28 Mar 2009 23:21:27 +0000 (+0000)
Subject: fix setuid sometimes wouldn't

4
Commit: f1191b50ec11c8e2ca766d6d99eb5bb9d2c084a3
Author: Al Viro 
Date: Mon, 30 Mar 2009 11:35:18 +0000 (-0400)
Subject: check_unsafe_exec() doesn't care about signal handlers sharing

Signed-off-by: Hugh Dickins 
Signed-off-by: Greg Kroah-Hartman