linux-toradex.git/arch, branch v3.0.65

x86/xen: don't assume %ds is usable in xen_iret for 32-bit PVOPS.

2013-02-17T18:46:20+00:00

commit 13d2b4d11d69a92574a55bfd985cfb0ca77aebdc upstream.

This fixes CVE-2013-0228 / XSA-42

Drew Jones while working on CVE-2013-0190 found that that unprivileged guest user
in 32bit PV guest can use to crash the > guest with the panic like this:

-------------
general protection fault: 0000 [#1] SMP
last sysfs file: /sys/devices/vbd-51712/block/xvda/dev
Modules linked in: sunrpc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4
iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6
xt_state nf_conntrack ip6table_filter ip6_tables ipv6 xen_netfront ext4
mbcache jbd2 xen_blkfront dm_mirror dm_region_hash dm_log dm_mod [last
unloaded: scsi_wait_scan]

Pid: 1250, comm: r Not tainted 2.6.32-356.el6.i686 #1
EIP: 0061:[] EFLAGS: 00010086 CPU: 0
EIP is at xen_iret+0x12/0x2b
EAX: eb8d0000 EBX: 00000001 ECX: 08049860 EDX: 00000010
ESI: 00000000 EDI: 003d0f00 EBP: b77f8388 ESP: eb8d1fe0
 DS: 0000 ES: 007b FS: 0000 GS: 00e0 SS: 0069
Process r (pid: 1250, ti=eb8d0000 task=c2953550 task.ti=eb8d0000)
Stack:
 00000000 0027f416 00000073 00000206 b77f8364 0000007b 00000000 00000000
Call Trace:
Code: c3 8b 44 24 18 81 4c 24 38 00 02 00 00 8d 64 24 30 e9 03 00 00 00
8d 76 00 f7 44 24 08 00 00 02 80 75 33 50 b8 00 e0 ff ff 21 e0 <8b> 40
10 8b 04 85 a0 f6 ab c0 8b 80 0c b0 b3 c0 f6 44 24 0d 02
EIP: [] xen_iret+0x12/0x2b SS:ESP 0069:eb8d1fe0
general protection fault: 0000 [#2]
---[ end trace ab0d29a492dcd330 ]---
Kernel panic - not syncing: Fatal exception
Pid: 1250, comm: r Tainted: G      D    ---------------
2.6.32-356.el6.i686 #1
Call Trace:
 [] ? panic+0x6e/0x122
 [] ? oops_end+0xbc/0xd0
 [] ? do_general_protection+0x0/0x210
 [] ? error_code+0x73/
-------------

Petr says: "
 I've analysed the bug and I think that xen_iret() cannot cope with
 mangled DS, in this case zeroed out (null selector/descriptor) by either
 xen_failsafe_callback() or RESTORE_REGS because the corresponding LDT
 entry was invalidated by the reproducer. "

Jan took a look at the preliminary patch and came up a fix that solves
this problem:

"This code gets called after all registers other than those handled by
IRET got already restored, hence a null selector in %ds or a non-null
one that got loaded from a code or read-only data descriptor would
cause a kernel mode fault (with the potential of crashing the kernel
as a whole, if panic_on_oops is set)."

The way to fix this is to realize that the we can only relay on the
registers that IRET restores. The two that are guaranteed are the
%cs and %ss as they are always fixed GDT selectors. Also they are
inaccessible from user mode - so they cannot be altered. This is
the approach taken in this patch.

Another alternative option suggested by Jan would be to relay on
the subtle realization that using the %ebp or %esp relative references uses
the %ss segment.  In which case we could switch from using %eax to %ebp and
would not need the %ss over-rides. That would also require one extra
instruction to compensate for the one place where the register is used
as scaled index. However Andrew pointed out that is too subtle and if
further work was to be done in this code-path it could escape folks attention
and lead to accidents.

Reviewed-by: Petr Matousek 
Reported-by: Petr Matousek 
Reviewed-by: Andrew Cooper 
Signed-off-by: Jan Beulich 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Greg Kroah-Hartman

x86/mm: Check if PUD is large when validating a kernel address

2013-02-17T18:46:20+00:00

commit 0ee364eb316348ddf3e0dfcd986f5f13f528f821 upstream.

A user reported the following oops when a backup process reads
/proc/kcore:

 BUG: unable to handle kernel paging request at ffffbb00ff33b000
 IP: [] kern_addr_valid+0xbe/0x110
 [...]

 Call Trace:
  [] read_kcore+0x17a/0x370
  [] proc_reg_read+0x77/0xc0
  [] vfs_read+0xc7/0x130
  [] sys_read+0x53/0xa0
  [] system_call_fastpath+0x16/0x1b

Investigation determined that the bug triggered when reading
system RAM at the 4G mark. On this system, that was the first
address using 1G pages for the virt->phys direct mapping so the
PUD is pointing to a physical address, not a PMD page.

The problem is that the page table walker in kern_addr_valid() is
not checking pud_large() and treats the physical address as if
it was a PMD.  If it happens to look like pmd_none then it'll
silently fail, probably returning zeros instead of real data. If
the data happens to look like a present PMD though, it will be
walked resulting in the oops above.

This patch adds the necessary pud_large() check.

Unfortunately the problem was not readily reproducible and now
they are running the backup program without accessing
/proc/kcore so the patch has not been validated but I think it
makes sense.

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Reviewed-by: Michal Hocko 
Acked-by: Johannes Weiner 
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20130211145236.GX21389@suse.de
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86-64: Replace left over sti/cli in ia32 audit exit code

2013-02-11T16:16:47+00:00

commit 40a1ef95da85843696fc3ebe5fce39b0db32669f upstream.

For some reason they didn't get replaced so far by their
paravirt equivalents, resulting in code to be run with
interrupts disabled that doesn't expect so (causing, in the
observed case, a BUG_ON() to trigger) when syscall auditing is
enabled.

David (Cc-ed) came up with an identical fix, so likely this can
be taken to count as an ack from him.

Reported-by: Peter Moody 
Signed-off-by: Jan Beulich 
Cc: David Vrabel 
Cc: Konrad Rzeszutek Wilk 
Link: http://lkml.kernel.org/r/5108E01902000078000BA9C5@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar 
Cc: Konrad Rzeszutek Wilk 
Cc: David Vrabel 
Tested-by: Peter Moody 
Signed-off-by: Greg Kroah-Hartman

x86/Sandy Bridge: Sandy Bridge workaround depends on CONFIG_PCI

2013-02-04T00:21:38+00:00

commit e43b3cec711a61edf047adf6204d542f3a659ef8 upstream.

early_pci_allowed() and read_pci_config_16() are only available if
CONFIG_PCI is defined.

Signed-off-by: H. Peter Anvin 
Cc: Jesse Barnes 
Signed-off-by: Abdallah Chatila

efi, x86: Pass a proper identity mapping in efi_call_phys_prelog

2013-02-04T00:21:38+00:00

commit b8f2c21db390273c3eaf0e5308faeaeb1e233840 upstream.

Update efi_call_phys_prelog to install an identity mapping of all available
memory.  This corrects a bug on very large systems with more then 512 GB in
which bios would not be able to access addresses above not in the mapping.

The result is a crash that looks much like this.

BUG: unable to handle kernel paging request at 000000effd870020
IP: [<0000000078bce331>] 0x78bce330
PGD 0
Oops: 0000 [#1] SMP
Modules linked in:
CPU 0
Pid: 0, comm: swapper/0 Tainted: G        W    3.8.0-rc1-next-20121224-medusa_ntz+ #2 Intel Corp. Stoutland Platform
RIP: 0010:[<0000000078bce331>]  [<0000000078bce331>] 0x78bce330
RSP: 0000:ffffffff81601d28  EFLAGS: 00010006
RAX: 0000000078b80e18 RBX: 0000000000000004 RCX: 0000000000000004
RDX: 0000000078bcf958 RSI: 0000000000002400 RDI: 8000000000000000
RBP: 0000000078bcf760 R08: 000000effd870000 R09: 0000000000000000
R10: 0000000000000000 R11: 00000000000000c3 R12: 0000000000000030
R13: 000000effd870000 R14: 0000000000000000 R15: ffff88effd870000
FS:  0000000000000000(0000) GS:ffff88effe400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000effd870020 CR3: 000000000160c000 CR4: 00000000000006b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper/0 (pid: 0, threadinfo ffffffff81600000, task ffffffff81614400)
Stack:
 0000000078b80d18 0000000000000004 0000000078bced7b ffff880078b81fff
 0000000000000000 0000000000000082 0000000078bce3a8 0000000000002400
 0000000060000202 0000000078b80da0 0000000078bce45d ffffffff8107cb5a
Call Trace:
 [] ? on_each_cpu+0x77/0x83
 [] ? change_page_attr_set_clr+0x32f/0x3ed
 [] ? efi_call4+0x46/0x80
 [] ? efi_enter_virtual_mode+0x1f5/0x305
 [] ? start_kernel+0x34a/0x3d2
 [] ? repair_env_string+0x60/0x60
 [] ? x86_64_start_reservations+0xba/0xc1
 [] ? early_idt_handlers+0x120/0x120
 [] ? x86_64_start_kernel+0x154/0x163
Code:  Bad RIP value.
RIP  [<0000000078bce331>] 0x78bce330
 RSP 
CR2: 000000effd870020
---[ end trace ead828934fef5eab ]---

Signed-off-by: Nathan Zimmer 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Signed-off-by: Robin Holt 
Signed-off-by: Matt Fleming 
Signed-off-by: Greg Kroah-Hartman

x86/msr: Add capabilities check

2013-02-04T00:21:38+00:00

commit c903f0456bc69176912dee6dd25c6a66ee1aed00 upstream.

At the moment the MSR driver only relies upon file system
checks. This means that anything as root with any capability set
can write to MSRs. Historically that wasn't very interesting but
on modern processors the MSRs are such that writing to them
provides several ways to execute arbitary code in kernel space.
Sample code and documentation on doing this is circulating and
MSR attacks are used on Windows 64bit rootkits already.

In the Linux case you still need to be able to open the device
file so the impact is fairly limited and reduces the security of
some capability and security model based systems down towards
that of a generic "root owns the box" setup.

Therefore they should require CAP_SYS_RAWIO to prevent an
elevation of capabilities. The impact of this is fairly minimal
on most setups because they don't have heavy use of
capabilities. Those using SELinux, SMACK or AppArmor rules might
want to consider if their rulesets on the MSR driver could be
tighter.

Signed-off-by: Alan Cox 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

ARM: DMA: Fix struct page iterator in dma_cache_maint() to work with sparsemem

2013-02-04T00:21:37+00:00

commit 15653371c67c3fbe359ae37b720639dd4c7b42c5 upstream.

Subhash Jadavani reported this partial backtrace:
  Now consider this call stack from MMC block driver (this is on the ARMv7
  based board):

  [] (v7_dma_inv_range+0x30/0x48) from [] (dma_cache_maint_page+0x1c4/0x24c)
  [] (dma_cache_maint_page+0x1c4/0x24c) from [] (___dma_page_cpu_to_dev+0x14/0x1c)
  [] (___dma_page_cpu_to_dev+0x14/0x1c) from [] (dma_map_sg+0x3c/0x114)

This is caused by incrementing the struct page pointer, and running off
the end of the sparsemem page array.  Fix this by incrementing by pfn
instead, and convert the pfn to a struct page.

Suggested-by: James Bottomley 
Tested-by: Subhash Jadavani 
Signed-off-by: Russell King 
Signed-off-by: Greg Kroah-Hartman

x86: Use enum instead of literals for trap values [PARTIAL]

2013-01-28T04:46:29+00:00

[Based on commit c94082656dac74257f63e91f78d5d458ac781fa5 upstream, only
taking the traps.h portion.]

The traps are referred to by their numbers and it can be difficult to
understand them while reading the code without context. This patch adds
enumeration of the trap numbers and replaces the numbers with the correct
enum for x86.

Signed-off-by: Kees Cook 
Link: http://lkml.kernel.org/r/20120310000710.GA32667@www.outflux.net
Signed-off-by: H. Peter Anvin 
Signed-off-by: Robin Holt 
Signed-off-by: Greg Kroah-Hartman

xen: Fix stack corruption in xen_failsafe_callback for 32bit PVOPS guests.

2013-01-21T19:44:59+00:00

commit 9174adbee4a9a49d0139f5d71969852b36720809 upstream.

This fixes CVE-2013-0190 / XSA-40

There has been an error on the xen_failsafe_callback path for failed
iret, which causes the stack pointer to be wrong when entering the
iret_exc error path.  This can result in the kernel crashing.

In the classic kernel case, the relevant code looked a little like:

        popl %eax      # Error code from hypervisor
        jz 5f
        addl $16,%esp
        jmp iret_exc   # Hypervisor said iret fault
5:      addl $16,%esp
                       # Hypervisor said segment selector fault

Here, there are two identical addls on either option of a branch which
appears to have been optimised by hoisting it above the jz, and
converting it to an lea, which leaves the flags register unaffected.

In the PVOPS case, the code looks like:

        popl_cfi %eax         # Error from the hypervisor
        lea 16(%esp),%esp     # Add $16 before choosing fault path
        CFI_ADJUST_CFA_OFFSET -16
        jz 5f
        addl $16,%esp         # Incorrectly adjust %esp again
        jmp iret_exc

It is possible unprivileged userspace applications to cause this
behaviour, for example by loading an LDT code selector, then changing
the code selector to be not-present.  At this point, there is a race
condition where it is possible for the hypervisor to return back to
userspace from an interrupt, fault on its own iret, and inject a
failsafe_callback into the kernel.

This bug has been present since the introduction of Xen PVOPS support
in commit 5ead97c84 (xen: Core Xen implementation), in 2.6.23.

Signed-off-by: Frediano Ziglio 
Signed-off-by: Andrew Cooper 
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Greg Kroah-Hartman

powerpc: fix wii_memory_fixups() compile error on 3.0.y tree

2013-01-21T19:44:59+00:00

[not upstream as the code involved was removed in the 3.3.0 release]

Fix wii_memory_fixups() the following compile error on 3.0.y tree with
wii_defconfig on 3.0.y tree.

  CC      arch/powerpc/platforms/embedded6xx/wii.o
arch/powerpc/platforms/embedded6xx/wii.c: In function ‘wii_memory_fixups’:
arch/powerpc/platforms/embedded6xx/wii.c:88:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 2 has type ‘phys_addr_t’ [-Werror=format]
arch/powerpc/platforms/embedded6xx/wii.c:88:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘phys_addr_t’ [-Werror=format]
arch/powerpc/platforms/embedded6xx/wii.c:90:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 2 has type ‘phys_addr_t’ [-Werror=format]
arch/powerpc/platforms/embedded6xx/wii.c:90:2: error: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘phys_addr_t’ [-Werror=format]
cc1: all warnings being treated as errors
make[2]: *** [arch/powerpc/platforms/embedded6xx/wii.o] Error 1
make[1]: *** [arch/powerpc/platforms/embedded6xx] Error 2
make: *** [arch/powerpc/platforms] Error 2

Signed-off-by: Shuah Khan 
Signed-off-by: Greg Kroah-Hartman