linux-stable.git/arch/powerpc/kernel, branch v3.14.78 Linux kernel stable tree powerpc/tm: Always reclaim in start_thread() for exec() class syscalls 2016-07-27T16:55:48+00:00 Cyril Bur cyrilbur@gmail.com 2016-06-17T04:58:34+00:00 ff19f63ed47309550b47831ac39176d9910fadfe commit 8e96a87c5431c256feb65bcfc5aec92d9f7839b6 upstream. Userspace can quite legitimately perform an exec() syscall with a suspended transaction. exec() does not return to the old process, rather it load a new one and starts that, the expectation therefore is that the new process starts not in a transaction. Currently exec() is not treated any differently to any other syscall which creates problems. Firstly it could allow a new process to start with a suspended transaction for a binary that no longer exists. This means that the checkpointed state won't be valid and if the suspended transaction were ever to be resumed and subsequently aborted (a possibility which is exceedingly likely as exec()ing will likely doom the transaction) the new process will jump to invalid state. Secondly the incorrect attempt to keep the transactional state while still zeroing state for the new process creates at least two TM Bad Things. The first triggers on the rfid to return to userspace as start_thread() has given the new process a 'clean' MSR but the suspend will still be set in the hardware MSR. The second TM Bad Thing triggers in __switch_to() as the processor is still transactionally suspended but __switch_to() wants to zero the TM sprs for the new process. This is an example of the outcome of calling exec() with a suspended transaction. Note the first 700 is likely the first TM bad thing decsribed earlier only the kernel can't report it as we've loaded userspace registers. c000000000009980 is the rfid in fast_exception_return() Bad kernel stack pointer 3fffcfa1a370 at c000000000009980 Oops: Bad kernel stack pointer, sig: 6 [#1] CPU: 0 PID: 2006 Comm: tm-execed Not tainted NIP: c000000000009980 LR: 0000000000000000 CTR: 0000000000000000 REGS: c00000003ffefd40 TRAP: 0700 Not tainted MSR: 8000000300201031 <SF,ME,IR,DR,LE,TM[SE]> CR: 00000000 XER: 00000000 CFAR: c0000000000098b4 SOFTE: 0 PACATMSCRATCH: b00000010000d033 GPR00: 0000000000000000 00003fffcfa1a370 0000000000000000 0000000000000000 GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR12: 00003fff966611c0 0000000000000000 0000000000000000 0000000000000000 NIP [c000000000009980] fast_exception_return+0xb0/0xb8 LR [0000000000000000] (null) Call Trace: Instruction dump: f84d0278 e9a100d8 7c7b03a6 e84101a0 7c4ff120 e8410170 7c5a03a6 e8010070 e8410080 e8610088 e8810090 e8210078 <4c000024> 48000000 e8610178 88ed023b Kernel BUG at c000000000043e80 [verbose debug info unavailable] Unexpected TM Bad Thing exception at c000000000043e80 (msr 0x201033) Oops: Unrecoverable exception, sig: 6 [#2] CPU: 0 PID: 2006 Comm: tm-execed Tainted: G D task: c0000000fbea6d80 ti: c00000003ffec000 task.ti: c0000000fb7ec000 NIP: c000000000043e80 LR: c000000000015a24 CTR: 0000000000000000 REGS: c00000003ffef7e0 TRAP: 0700 Tainted: G D MSR: 8000000300201033 <SF,ME,IR,DR,RI,LE,TM[SE]> CR: 28002828 XER: 00000000 CFAR: c000000000015a20 SOFTE: 0 PACATMSCRATCH: b00000010000d033 GPR00: 0000000000000000 c00000003ffefa60 c000000000db5500 c0000000fbead000 GPR04: 8000000300001033 2222222222222222 2222222222222222 00000000ff160000 GPR08: 0000000000000000 800000010000d033 c0000000fb7e3ea0 c00000000fe00004 GPR12: 0000000000002200 c00000000fe00000 0000000000000000 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 0000000000000000 c0000000fbea7410 00000000ff160000 GPR24: c0000000ffe1f600 c0000000fbea8700 c0000000fbea8700 c0000000fbead000 GPR28: c000000000e20198 c0000000fbea6d80 c0000000fbeab680 c0000000fbea6d80 NIP [c000000000043e80] tm_restore_sprs+0xc/0x1c LR [c000000000015a24] __switch_to+0x1f4/0x420 Call Trace: Instruction dump: 7c800164 4e800020 7c0022a6 f80304a8 7c0222a6 f80304b0 7c0122a6 f80304b8 4e800020 e80304a8 7c0023a6 e80304b0 <7c0223a6> e80304b8 7c0123a6 4e800020 This fixes CVE-2016-5828. Fixes: bc2a9408fa65 ("powerpc: Hook in new transactional memory code") Signed-off-by: Cyril Bur <cyrilbur@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8e96a87c5431c256feb65bcfc5aec92d9f7839b6 upstream.

Userspace can quite legitimately perform an exec() syscall with a
suspended transaction. exec() does not return to the old process, rather
it load a new one and starts that, the expectation therefore is that the
new process starts not in a transaction. Currently exec() is not treated
any differently to any other syscall which creates problems.

Firstly it could allow a new process to start with a suspended
transaction for a binary that no longer exists. This means that the
checkpointed state won't be valid and if the suspended transaction were
ever to be resumed and subsequently aborted (a possibility which is
exceedingly likely as exec()ing will likely doom the transaction) the
new process will jump to invalid state.

Secondly the incorrect attempt to keep the transactional state while
still zeroing state for the new process creates at least two TM Bad
Things. The first triggers on the rfid to return to userspace as
start_thread() has given the new process a 'clean' MSR but the suspend
will still be set in the hardware MSR. The second TM Bad Thing triggers
in __switch_to() as the processor is still transactionally suspended but
__switch_to() wants to zero the TM sprs for the new process.

This is an example of the outcome of calling exec() with a suspended
transaction. Note the first 700 is likely the first TM bad thing
decsribed earlier only the kernel can't report it as we've loaded
userspace registers. c000000000009980 is the rfid in
fast_exception_return()

  Bad kernel stack pointer 3fffcfa1a370 at c000000000009980
  Oops: Bad kernel stack pointer, sig: 6 [#1]
  CPU: 0 PID: 2006 Comm: tm-execed Not tainted
  NIP: c000000000009980 LR: 0000000000000000 CTR: 0000000000000000
  REGS: c00000003ffefd40 TRAP: 0700   Not tainted
  MSR: 8000000300201031 <SF,ME,IR,DR,LE,TM[SE]>  CR: 00000000  XER: 00000000
  CFAR: c0000000000098b4 SOFTE: 0
  PACATMSCRATCH: b00000010000d033
  GPR00: 0000000000000000 00003fffcfa1a370 0000000000000000 0000000000000000
  GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR12: 00003fff966611c0 0000000000000000 0000000000000000 0000000000000000
  NIP [c000000000009980] fast_exception_return+0xb0/0xb8
  LR [0000000000000000]           (null)
  Call Trace:
  Instruction dump:
  f84d0278 e9a100d8 7c7b03a6 e84101a0 7c4ff120 e8410170 7c5a03a6 e8010070
  e8410080 e8610088 e8810090 e8210078 <4c000024> 48000000 e8610178 88ed023b

  Kernel BUG at c000000000043e80 [verbose debug info unavailable]
  Unexpected TM Bad Thing exception at c000000000043e80 (msr 0x201033)
  Oops: Unrecoverable exception, sig: 6 [#2]
  CPU: 0 PID: 2006 Comm: tm-execed Tainted: G      D
  task: c0000000fbea6d80 ti: c00000003ffec000 task.ti: c0000000fb7ec000
  NIP: c000000000043e80 LR: c000000000015a24 CTR: 0000000000000000
  REGS: c00000003ffef7e0 TRAP: 0700   Tainted: G      D
  MSR: 8000000300201033 <SF,ME,IR,DR,RI,LE,TM[SE]>  CR: 28002828  XER: 00000000
  CFAR: c000000000015a20 SOFTE: 0
  PACATMSCRATCH: b00000010000d033
  GPR00: 0000000000000000 c00000003ffefa60 c000000000db5500 c0000000fbead000
  GPR04: 8000000300001033 2222222222222222 2222222222222222 00000000ff160000
  GPR08: 0000000000000000 800000010000d033 c0000000fb7e3ea0 c00000000fe00004
  GPR12: 0000000000002200 c00000000fe00000 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR20: 0000000000000000 0000000000000000 c0000000fbea7410 00000000ff160000
  GPR24: c0000000ffe1f600 c0000000fbea8700 c0000000fbea8700 c0000000fbead000
  GPR28: c000000000e20198 c0000000fbea6d80 c0000000fbeab680 c0000000fbea6d80
  NIP [c000000000043e80] tm_restore_sprs+0xc/0x1c
  LR [c000000000015a24] __switch_to+0x1f4/0x420
  Call Trace:
  Instruction dump:
  7c800164 4e800020 7c0022a6 f80304a8 7c0222a6 f80304b0 7c0122a6 f80304b8
  4e800020 e80304a8 7c0023a6 e80304b0 <7c0223a6> e80304b8 7c0123a6 4e800020

This fixes CVE-2016-5828.

Fixes: bc2a9408fa65 ("powerpc: Hook in new transactional memory code")
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/book3s64: Fix branching to OOL handlers in relocatable kernel 2016-06-08T00:21:58+00:00 Hari Bathini hbathini@linux.vnet.ibm.com 2016-04-15T12:48:02+00:00 646e7ae79a3dafa5b8b117a0d04405951634ad41 commit 8ed8ab40047a570fdd8043a40c104a57248dd3fd upstream. Some of the interrupt vectors on 64-bit POWER server processors are only 32 bytes long (8 instructions), which is not enough for the full first-level interrupt handler. For these we need to branch to an out-of-line (OOL) handler. But when we are running a relocatable kernel, interrupt vectors till __end_interrupts marker are copied down to real address 0x100. So, branching to labels (ie. OOL handlers) outside this section must be handled differently (see LOAD_HANDLER()), considering relocatable kernel, which would need at least 4 instructions. However, branching from interrupt vector means that we corrupt the CFAR (come-from address register) on POWER7 and later processors as mentioned in commit 1707dd16. So, EXCEPTION_PROLOG_0 (6 instructions) that contains the part up to the point where the CFAR is saved in the PACA should be part of the short interrupt vectors before we branch out to OOL handlers. But as mentioned already, there are interrupt vectors on 64-bit POWER server processors that are only 32 bytes long (like vectors 0x4f00, 0x4f20, etc.), which cannot accomodate the above two cases at the same time owing to space constraint. Currently, in these interrupt vectors, we simply branch out to OOL handlers, without using LOAD_HANDLER(), which leaves us vulnerable when running a relocatable kernel (eg. kdump case). While this has been the case for sometime now and kdump is used widely, we were fortunate not to see any problems so far, for three reasons: 1. In almost all cases, production kernel (relocatable) is used for kdump as well, which would mean that crashed kernel's OOL handler would be at the same place where we end up branching to, from short interrupt vector of kdump kernel. 2. Also, OOL handler was unlikely the reason for crash in almost all the kdump scenarios, which meant we had a sane OOL handler from crashed kernel that we branched to. 3. On most 64-bit POWER server processors, page size is large enough that marking interrupt vector code as executable (see commit 429d2e83) leads to marking OOL handler code from crashed kernel, that sits right below interrupt vector code from kdump kernel, as executable as well. Let us fix this by moving the __end_interrupts marker down past OOL handlers to make sure that we also copy OOL handlers to real address 0x100 when running a relocatable kernel. This fix has been tested successfully in kdump scenario, on an LPAR with 4K page size by using different default/production kernel and kdump kernel. Also tested by manually corrupting the OOL handlers in the first kernel and then kdump'ing, and then causing the OOL handlers to fire - mpe. Fixes: c1fb6816fb1b ("powerpc: Add relocation on exception vector handlers") Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com> Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8ed8ab40047a570fdd8043a40c104a57248dd3fd upstream.

Some of the interrupt vectors on 64-bit POWER server processors are only
32 bytes long (8 instructions), which is not enough for the full
first-level interrupt handler. For these we need to branch to an
out-of-line (OOL) handler. But when we are running a relocatable kernel,
interrupt vectors till __end_interrupts marker are copied down to real
address 0x100. So, branching to labels (ie. OOL handlers) outside this
section must be handled differently (see LOAD_HANDLER()), considering
relocatable kernel, which would need at least 4 instructions.

However, branching from interrupt vector means that we corrupt the
CFAR (come-from address register) on POWER7 and later processors as
mentioned in commit 1707dd16. So, EXCEPTION_PROLOG_0 (6 instructions)
that contains the part up to the point where the CFAR is saved in the
PACA should be part of the short interrupt vectors before we branch out
to OOL handlers.

But as mentioned already, there are interrupt vectors on 64-bit POWER
server processors that are only 32 bytes long (like vectors 0x4f00,
0x4f20, etc.), which cannot accomodate the above two cases at the same
time owing to space constraint. Currently, in these interrupt vectors,
we simply branch out to OOL handlers, without using LOAD_HANDLER(),
which leaves us vulnerable when running a relocatable kernel (eg. kdump
case). While this has been the case for sometime now and kdump is used
widely, we were fortunate not to see any problems so far, for three
reasons:

  1. In almost all cases, production kernel (relocatable) is used for
     kdump as well, which would mean that crashed kernel's OOL handler
     would be at the same place where we end up branching to, from short
     interrupt vector of kdump kernel.
  2. Also, OOL handler was unlikely the reason for crash in almost all
     the kdump scenarios, which meant we had a sane OOL handler from
     crashed kernel that we branched to.
  3. On most 64-bit POWER server processors, page size is large enough
     that marking interrupt vector code as executable (see commit
     429d2e83) leads to marking OOL handler code from crashed kernel,
     that sits right below interrupt vector code from kdump kernel, as
     executable as well.

Let us fix this by moving the __end_interrupts marker down past OOL
handlers to make sure that we also copy OOL handlers to real address
0x100 when running a relocatable kernel.

This fix has been tested successfully in kdump scenario, on an LPAR with
4K page size by using different default/production kernel and kdump
kernel.

Also tested by manually corrupting the OOL handlers in the first kernel
and then kdump'ing, and then causing the OOL handlers to fire - mpe.

Fixes: c1fb6816fb1b ("powerpc: Add relocation on exception vector handlers")
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc: scan_features() updates incorrect bits for REAL_LE 2016-05-11T09:21:03+00:00 Anton Blanchard anton@samba.org 2016-04-15T02:06:13+00:00 da039ec537e0eac108c9934e8e0c04a1f76df3a9 commit 6997e57d693b07289694239e52a10d2f02c3a46f upstream. The REAL_LE feature entry in the ibm_pa_feature struct is missing an MMU feature value, meaning all the remaining elements initialise the wrong values. This means instead of checking for byte 5, bit 0, we check for byte 0, bit 0, and then we incorrectly set the CPU feature bit as well as MMU feature bit 1 and CPU user feature bits 0 and 2 (5). Checking byte 0 bit 0 (IBM numbering), means we're looking at the "Memory Management Unit (MMU)" feature - ie. does the CPU have an MMU. In practice that bit is set on all platforms which have the property. This means we set CPU_FTR_REAL_LE always. In practice that seems not to matter because all the modern cpus which have this property also implement REAL_LE, and we've never needed to disable it. We're also incorrectly setting MMU feature bit 1, which is: #define MMU_FTR_TYPE_8xx 0x00000002 Luckily the only place that looks for MMU_FTR_TYPE_8xx is in Book3E code, which can't run on the same cpus as scan_features(). So this also doesn't matter in practice. Finally in the CPU user feature mask, we're setting bits 0 and 2. Bit 2 is not currently used, and bit 0 is: #define PPC_FEATURE_PPC_LE 0x00000001 Which says the CPU supports the old style "PPC Little Endian" mode. Again this should be harmless in practice as no 64-bit CPUs implement that mode. Fix the code by adding the missing initialisation of the MMU feature. Also add a comment marking CPU user feature bit 2 (0x4) as reserved. It would be unsafe to start using it as old kernels incorrectly set it. Fixes: 44ae3ab3358e ("powerpc: Free up some CPU feature bits by moving out MMU-related features") Signed-off-by: Anton Blanchard <anton@samba.org> [mpe: Flesh out changelog, add comment reserving 0x4] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6997e57d693b07289694239e52a10d2f02c3a46f upstream.

The REAL_LE feature entry in the ibm_pa_feature struct is missing an MMU
feature value, meaning all the remaining elements initialise the wrong
values.

This means instead of checking for byte 5, bit 0, we check for byte 0,
bit 0, and then we incorrectly set the CPU feature bit as well as MMU
feature bit 1 and CPU user feature bits 0 and 2 (5).

Checking byte 0 bit 0 (IBM numbering), means we're looking at the
"Memory Management Unit (MMU)" feature - ie. does the CPU have an MMU.
In practice that bit is set on all platforms which have the property.

This means we set CPU_FTR_REAL_LE always. In practice that seems not to
matter because all the modern cpus which have this property also
implement REAL_LE, and we've never needed to disable it.

We're also incorrectly setting MMU feature bit 1, which is:

  #define MMU_FTR_TYPE_8xx		0x00000002

Luckily the only place that looks for MMU_FTR_TYPE_8xx is in Book3E
code, which can't run on the same cpus as scan_features(). So this also
doesn't matter in practice.

Finally in the CPU user feature mask, we're setting bits 0 and 2. Bit 2
is not currently used, and bit 0 is:

  #define PPC_FEATURE_PPC_LE		0x00000001

Which says the CPU supports the old style "PPC Little Endian" mode.
Again this should be harmless in practice as no 64-bit CPUs implement
that mode.

Fix the code by adding the missing initialisation of the MMU feature.

Also add a comment marking CPU user feature bit 2 (0x4) as reserved. It
would be unsafe to start using it as old kernels incorrectly set it.

Fixes: 44ae3ab3358e ("powerpc: Free up some CPU feature bits by moving out MMU-related features")
Signed-off-by: Anton Blanchard <anton@samba.org>
[mpe: Flesh out changelog, add comment reserving 0x4]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc: Fix dedotify for binutils >= 2.26 2016-03-16T15:42:20+00:00 Andreas Schwab schwab@linux-m68k.org 2016-02-05T18:50:03+00:00 912027661329cbd708d23e99aa25df971410842c commit f15838e9cac8f78f0cc506529bb9d3b9fa589c1f upstream. Since binutils 2.26 BFD is doing suffix merging on STRTAB sections. But dedotify modifies the symbol names in place, which can also modify unrelated symbols with a name that matches a suffix of a dotted name. To remove the leading dot of a symbol name we can just increment the pointer into the STRTAB section instead. Backport to all stables to avoid breakage when people update their binutils - mpe. Signed-off-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f15838e9cac8f78f0cc506529bb9d3b9fa589c1f upstream.

Since binutils 2.26 BFD is doing suffix merging on STRTAB sections.  But
dedotify modifies the symbol names in place, which can also modify
unrelated symbols with a name that matches a suffix of a dotted name.  To
remove the leading dot of a symbol name we can just increment the pointer
into the STRTAB section instead.

Backport to all stables to avoid breakage when people update their
binutils - mpe.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/tm: Check for already reclaimed tasks 2016-01-29T05:57:14+00:00 Michael Neuling mikey@neuling.org 2015-11-19T04:44:45+00:00 70812a4226708100041da6715a1d5bb2e3aebc34 commit 7f821fc9c77a9b01fe7b1d6e72717b33d8d64142 upstream. Currently we can hit a scenario where we'll tm_reclaim() twice. This results in a TM bad thing exception because the second reclaim occurs when not in suspend mode. The scenario in which this can happen is the following. We attempt to deliver a signal to userspace. To do this we need obtain the stack pointer to write the signal context. To get this stack pointer we must tm_reclaim() in case we need to use the checkpointed stack pointer (see get_tm_stackpointer()). Normally we'd then return directly to userspace to deliver the signal without going through __switch_to(). Unfortunatley, if at this point we get an error (such as a bad userspace stack pointer), we need to exit the process. The exit will result in a __switch_to(). __switch_to() will attempt to save the process state which results in another tm_reclaim(). This tm_reclaim() now causes a TM Bad Thing exception as this state has already been saved and the processor is no longer in TM suspend mode. Whee! This patch checks the state of the MSR to ensure we are TM suspended before we attempt the tm_reclaim(). If we've already saved the state away, we should no longer be in TM suspend mode. This has the additional advantage of checking for a potential TM Bad Thing exception. Found using syscall fuzzer. Fixes: fb09692e71f1 ("powerpc: Add reclaim and recheckpoint functions for context switching transactional memory processes") Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 7f821fc9c77a9b01fe7b1d6e72717b33d8d64142 upstream.

Currently we can hit a scenario where we'll tm_reclaim() twice.  This
results in a TM bad thing exception because the second reclaim occurs
when not in suspend mode.

The scenario in which this can happen is the following.  We attempt to
deliver a signal to userspace.  To do this we need obtain the stack
pointer to write the signal context.  To get this stack pointer we
must tm_reclaim() in case we need to use the checkpointed stack
pointer (see get_tm_stackpointer()).  Normally we'd then return
directly to userspace to deliver the signal without going through
__switch_to().

Unfortunatley, if at this point we get an error (such as a bad
userspace stack pointer), we need to exit the process.  The exit will
result in a __switch_to().  __switch_to() will attempt to save the
process state which results in another tm_reclaim().  This
tm_reclaim() now causes a TM Bad Thing exception as this state has
already been saved and the processor is no longer in TM suspend mode.
Whee!

This patch checks the state of the MSR to ensure we are TM suspended
before we attempt the tm_reclaim().  If we've already saved the state
away, we should no longer be in TM suspend mode.  This has the
additional advantage of checking for a potential TM Bad Thing
exception.

Found using syscall fuzzer.

Fixes: fb09692e71f1 ("powerpc: Add reclaim and recheckpoint functions for context switching transactional memory processes")
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/tm: Block signal return setting invalid MSR state 2016-01-29T05:57:13+00:00 Michael Neuling mikey@neuling.org 2015-11-19T04:44:44+00:00 a327f0569b21b62942dc28aacb9dbbda236ef7a2 commit d2b9d2a5ad5ef04ff978c9923d19730cb05efd55 upstream. Currently we allow both the MSR T and S bits to be set by userspace on a signal return. Unfortunately this is a reserved configuration and will cause a TM Bad Thing exception if attempted (via rfid). This patch checks for this case in both the 32 and 64 bit signals code. If both T and S are set, we mark the context as invalid. Found using a syscall fuzzer. Fixes: 2b0a576d15e0 ("powerpc: Add new transactional memory state to the signal context") Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d2b9d2a5ad5ef04ff978c9923d19730cb05efd55 upstream.

Currently we allow both the MSR T and S bits to be set by userspace on
a signal return.  Unfortunately this is a reserved configuration and
will cause a TM Bad Thing exception if attempted (via rfid).

This patch checks for this case in both the 32 and 64 bit signals
code.  If both T and S are set, we mark the context as invalid.

Found using a syscall fuzzer.

Fixes: 2b0a576d15e0 ("powerpc: Add new transactional memory state to the signal context")
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/rtas: Validate rtas.entry before calling enter_rtas() 2015-11-09T20:50:24+00:00 Vasant Hegde hegdevasant@linux.vnet.ibm.com 2015-10-16T10:23:29+00:00 49c8037b80f74c69546b8cadcd637fefe6ac645d commit 8832317f662c06f5c06e638f57bfe89a71c9b266 upstream. Currently we do not validate rtas.entry before calling enter_rtas(). This leads to a kernel oops when user space calls rtas system call on a powernv platform (see below). This patch adds code to validate rtas.entry before making enter_rtas() call. Oops: Exception in kernel mode, sig: 4 [#1] SMP NR_CPUS=1024 NUMA PowerNV task: c000000004294b80 ti: c0000007e1a78000 task.ti: c0000007e1a78000 NIP: 0000000000000000 LR: 0000000000009c14 CTR: c000000000423140 REGS: c0000007e1a7b920 TRAP: 0e40 Not tainted (3.18.17-340.el7_1.pkvm3_1_0.2400.1.ppc64le) MSR: 1000000000081000 <HV,ME> CR: 00000000 XER: 00000000 CFAR: c000000000009c0c SOFTE: 0 NIP [0000000000000000] (null) LR [0000000000009c14] 0x9c14 Call Trace: [c0000007e1a7bba0] [c00000000041a7f4] avc_has_perm_noaudit+0x54/0x110 (unreliable) [c0000007e1a7bd80] [c00000000002ddc0] ppc_rtas+0x150/0x2d0 [c0000007e1a7be30] [c000000000009358] syscall_exit+0x0/0x98 Fixes: 55190f88789a ("powerpc: Add skeleton PowerNV platform") Reported-by: NAGESWARA R. SASTRY <nasastry@in.ibm.com> Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com> [mpe: Reword change log, trim oops, and add stable + fixes] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8832317f662c06f5c06e638f57bfe89a71c9b266 upstream.

Currently we do not validate rtas.entry before calling enter_rtas(). This
leads to a kernel oops when user space calls rtas system call on a powernv
platform (see below). This patch adds code to validate rtas.entry before
making enter_rtas() call.

  Oops: Exception in kernel mode, sig: 4 [#1]
  SMP NR_CPUS=1024 NUMA PowerNV
  task: c000000004294b80 ti: c0000007e1a78000 task.ti: c0000007e1a78000
  NIP: 0000000000000000 LR: 0000000000009c14 CTR: c000000000423140
  REGS: c0000007e1a7b920 TRAP: 0e40   Not tainted  (3.18.17-340.el7_1.pkvm3_1_0.2400.1.ppc64le)
  MSR: 1000000000081000 <HV,ME>  CR: 00000000  XER: 00000000
  CFAR: c000000000009c0c SOFTE: 0
  NIP [0000000000000000]           (null)
  LR [0000000000009c14] 0x9c14
  Call Trace:
  [c0000007e1a7bba0] [c00000000041a7f4] avc_has_perm_noaudit+0x54/0x110 (unreliable)
  [c0000007e1a7bd80] [c00000000002ddc0] ppc_rtas+0x150/0x2d0
  [c0000007e1a7be30] [c000000000009358] syscall_exit+0x0/0x98

Fixes: 55190f88789a ("powerpc: Add skeleton PowerNV platform")
Reported-by: NAGESWARA R. SASTRY <nasastry@in.ibm.com>
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[mpe: Reword change log, trim oops, and add stable + fixes]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers 2015-10-01T09:36:10+00:00 Thomas Huth thuth@redhat.com 2015-07-17T10:46:58+00:00 4d14a9e6fb8bc461bc62a4289bd4bbca7cd610b3 commit 1c2cb594441d02815d304cccec9742ff5c707495 upstream. The EPOW interrupt handler uses rtas_get_sensor(), which in turn uses rtas_busy_delay() to wait for RTAS becoming ready in case it is necessary. But rtas_busy_delay() is annotated with might_sleep() and thus may not be used by interrupts handlers like the EPOW handler! This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is enabled: BUG: sleeping function called from invalid context at arch/powerpc/kernel/rtas.c:496 in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2-thuth #6 Call Trace: [c00000007ffe7b90] [c000000000807670] dump_stack+0xa0/0xdc (unreliable) [c00000007ffe7bc0] [c0000000000e1f14] ___might_sleep+0x134/0x180 [c00000007ffe7c20] [c00000000002aec0] rtas_busy_delay+0x30/0xd0 [c00000007ffe7c50] [c00000000002bde4] rtas_get_sensor+0x74/0xe0 [c00000007ffe7ce0] [c000000000083264] ras_epow_interrupt+0x44/0x450 [c00000007ffe7d90] [c000000000120260] handle_irq_event_percpu+0xa0/0x300 [c00000007ffe7e70] [c000000000120524] handle_irq_event+0x64/0xc0 [c00000007ffe7eb0] [c000000000124dbc] handle_fasteoi_irq+0xec/0x260 [c00000007ffe7ef0] [c00000000011f4f0] generic_handle_irq+0x50/0x80 [c00000007ffe7f20] [c000000000010f3c] __do_irq+0x8c/0x200 [c00000007ffe7f90] [c0000000000236cc] call_do_irq+0x14/0x24 [c00000007e6f39e0] [c000000000011144] do_IRQ+0x94/0x110 [c00000007e6f3a30] [c000000000002594] hardware_interrupt_common+0x114/0x180 Fix this issue by introducing a new rtas_get_sensor_fast() function that does not use rtas_busy_delay() - and thus can only be used for sensors that do not cause a BUSY condition - known as "fast" sensors. The EPOW sensor is defined to be "fast" in sPAPR - mpe. Fixes: 587f83e8dd50 ("powerpc/pseries: Use rtas_get_sensor in RAS code") Signed-off-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1c2cb594441d02815d304cccec9742ff5c707495 upstream.

The EPOW interrupt handler uses rtas_get_sensor(), which in turn
uses rtas_busy_delay() to wait for RTAS becoming ready in case it
is necessary. But rtas_busy_delay() is annotated with might_sleep()
and thus may not be used by interrupts handlers like the EPOW handler!
This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is
enabled:

 BUG: sleeping function called from invalid context at arch/powerpc/kernel/rtas.c:496
 in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2-thuth #6
 Call Trace:
 [c00000007ffe7b90] [c000000000807670] dump_stack+0xa0/0xdc (unreliable)
 [c00000007ffe7bc0] [c0000000000e1f14] ___might_sleep+0x134/0x180
 [c00000007ffe7c20] [c00000000002aec0] rtas_busy_delay+0x30/0xd0
 [c00000007ffe7c50] [c00000000002bde4] rtas_get_sensor+0x74/0xe0
 [c00000007ffe7ce0] [c000000000083264] ras_epow_interrupt+0x44/0x450
 [c00000007ffe7d90] [c000000000120260] handle_irq_event_percpu+0xa0/0x300
 [c00000007ffe7e70] [c000000000120524] handle_irq_event+0x64/0xc0
 [c00000007ffe7eb0] [c000000000124dbc] handle_fasteoi_irq+0xec/0x260
 [c00000007ffe7ef0] [c00000000011f4f0] generic_handle_irq+0x50/0x80
 [c00000007ffe7f20] [c000000000010f3c] __do_irq+0x8c/0x200
 [c00000007ffe7f90] [c0000000000236cc] call_do_irq+0x14/0x24
 [c00000007e6f39e0] [c000000000011144] do_IRQ+0x94/0x110
 [c00000007e6f3a30] [c000000000002594] hardware_interrupt_common+0x114/0x180

Fix this issue by introducing a new rtas_get_sensor_fast() function
that does not use rtas_busy_delay() - and thus can only be used for
sensors that do not cause a BUSY condition - known as "fast" sensors.

The EPOW sensor is defined to be "fast" in sPAPR - mpe.

Fixes: 587f83e8dd50 ("powerpc/pseries: Use rtas_get_sensor in RAS code")
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
signal: fix information leak in copy_siginfo_from_user32 2015-08-17T03:51:52+00:00 Amanieu d'Antras amanieu@gmail.com 2015-08-06T22:46:26+00:00 a209694c3e37569b5f6136cc9181b3ac42fa61f3 commit 3c00cb5e68dc719f2fc73a33b1b230aadfcb1309 upstream. This function can leak kernel stack data when the user siginfo_t has a positive si_code value. The top 16 bits of si_code descibe which fields in the siginfo_t union are active, but they are treated inconsistently between copy_siginfo_from_user32, copy_siginfo_to_user32 and copy_siginfo_to_user. copy_siginfo_from_user32 is called from rt_sigqueueinfo and rt_tgsigqueueinfo in which the user has full control overthe top 16 bits of si_code. This fixes the following information leaks: x86: 8 bytes leaked when sending a signal from a 32-bit process to itself. This leak grows to 16 bytes if the process uses x32. (si_code = __SI_CHLD) x86: 100 bytes leaked when sending a signal from a 32-bit process to a 64-bit process. (si_code = -1) sparc: 4 bytes leaked when sending a signal from a 32-bit process to a 64-bit process. (si_code = any) parsic and s390 have similar bugs, but they are not vulnerable because rt_[tg]sigqueueinfo have checks that prevent sending a positive si_code to a different process. These bugs are also fixed for consistency. Signed-off-by: Amanieu d'Antras <amanieu@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3c00cb5e68dc719f2fc73a33b1b230aadfcb1309 upstream.

This function can leak kernel stack data when the user siginfo_t has a
positive si_code value.  The top 16 bits of si_code descibe which fields
in the siginfo_t union are active, but they are treated inconsistently
between copy_siginfo_from_user32, copy_siginfo_to_user32 and
copy_siginfo_to_user.

copy_siginfo_from_user32 is called from rt_sigqueueinfo and
rt_tgsigqueueinfo in which the user has full control overthe top 16 bits
of si_code.

This fixes the following information leaks:
x86:   8 bytes leaked when sending a signal from a 32-bit process to
       itself. This leak grows to 16 bytes if the process uses x32.
       (si_code = __SI_CHLD)
x86:   100 bytes leaked when sending a signal from a 32-bit process to
       a 64-bit process. (si_code = -1)
sparc: 4 bytes leaked when sending a signal from a 32-bit process to a
       64-bit process. (si_code = any)

parsic and s390 have similar bugs, but they are not vulnerable because
rt_[tg]sigqueueinfo have checks that prevent sending a positive si_code
to a different process.  These bugs are also fixed for consistency.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
powerpc: Align TOC to 256 bytes 2015-06-06T15:19:35+00:00 Anton Blanchard anton@samba.org 2015-05-14T04:45:40+00:00 e28e66f7c51d40c2f0d8e6e916f26d34d009f737 commit 5e95235ccd5442d4a4fe11ec4eb99ba1b7959368 upstream. Recent toolchains force the TOC to be 256 byte aligned. We need to enforce this alignment in our linker script, otherwise pointers to our TOC variables (__toc_start, __prom_init_toc_start) could be incorrect. If they are bad, we die a few hundred instructions into boot. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 5e95235ccd5442d4a4fe11ec4eb99ba1b7959368 upstream.

Recent toolchains force the TOC to be 256 byte aligned. We need
to enforce this alignment in our linker script, otherwise pointers
to our TOC variables (__toc_start, __prom_init_toc_start) could
be incorrect.

If they are bad, we die a few hundred instructions into boot.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>