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f16d80b75a
linux/arch/powerpc
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Michael Neuling f16d80b75a powerpc/tm: Fix oops on sigreturn on systems without TM 
On systems like P9 powernv where we have no TM (or P8 booted with
ppc_tm=off), userspace can construct a signal context which still has
the MSR TS bits set. The kernel tries to restore this context which
results in the following crash:

  Unexpected TM Bad Thing exception at c0000000000022fc (msr 0x8000000102a03031) tm_scratch=800000020280f033
  Oops: Unrecoverable exception, sig: 6 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in:
  CPU: 0 PID: 1636 Comm: sigfuz Not tainted 5.2.0-11043-g0a8ad0ffa4 #69
  NIP:  c0000000000022fc LR: 00007fffb2d67e48 CTR: 0000000000000000
  REGS: c00000003fffbd70 TRAP: 0700   Not tainted  (5.2.0-11045-g7142b497d8)
  MSR:  8000000102a03031 <SF,VEC,VSX,FP,ME,IR,DR,LE,TM[E]>  CR: 42004242  XER: 00000000
  CFAR: c0000000000022e0 IRQMASK: 0
  GPR00: 0000000000000072 00007fffb2b6e560 00007fffb2d87f00 0000000000000669
  GPR04: 00007fffb2b6e728 0000000000000000 0000000000000000 00007fffb2b6f2a8
  GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR12: 0000000000000000 00007fffb2b76900 0000000000000000 0000000000000000
  GPR16: 00007fffb2370000 00007fffb2d84390 00007fffea3a15ac 000001000a250420
  GPR20: 00007fffb2b6f260 0000000010001770 0000000000000000 0000000000000000
  GPR24: 00007fffb2d843a0 00007fffea3a14a0 0000000000010000 0000000000800000
  GPR28: 00007fffea3a14d8 00000000003d0f00 0000000000000000 00007fffb2b6e728
  NIP [c0000000000022fc] rfi_flush_fallback+0x7c/0x80
  LR [00007fffb2d67e48] 0x7fffb2d67e48
  Call Trace:
  Instruction dump:
  e96a0220 e96a02a8 e96a0330 e96a03b8 394a0400 4200ffdc 7d2903a6 e92d0c00
  e94d0c08 e96d0c10 e82d0c18 7db242a6 <4c000024> 7db243a6 7db142a6 f82d0c18

The problem is the signal code assumes TM is enabled when
CONFIG_PPC_TRANSACTIONAL_MEM is enabled. This may not be the case as
with P9 powernv or if `ppc_tm=off` is used on P8.

This means any local user can crash the system.

Fix the problem by returning a bad stack frame to the user if they try
to set the MSR TS bits with sigreturn() on systems where TM is not
supported.

Found with sigfuz kernel selftest on P9.

This fixes CVE-2019-13648.

Fixes: 2b0a576d15 ("powerpc: Add new transactional memory state to the signal context")
Cc: stable@vger.kernel.org # v3.9
Reported-by: Praveen Pandey <Praveen.Pandey@in.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190719050502.405-1-mikey@neuling.org
2019-07-22 13:05:23 +10:00
..
boot powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
configs powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
include powerpc/pmu: Set pmcregs_in_use in paca when running as LPAR 2019-07-15 12:41:26 +10:00
kernel powerpc/tm: Fix oops on sigreturn on systems without TM 2019-07-22 13:05:23 +10:00
kvm KVM: PPC: Book3S HV: XIVE: fix rollback when kvmppc_xive_create fails 2019-07-19 13:41:12 +10:00
lib powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
math-emu treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
mm powerpc: fix off by one in max_zone_pfn initialization for ZONE_DMA 2019-07-15 14:55:58 +10:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-06-17 20:20:36 -07:00
oprofile treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
perf powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
platforms powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
purgatory treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
sysdev powerpc/xive: Fix loop exit-condition in xive_find_target_in_mask() 2019-07-18 23:47:16 +10:00
tools treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xmon powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig powerpc/dma: Fix invalid DMA mmap behavior 2019-07-19 21:29:49 +10:00
Kconfig.debug powerpc/xmon: add read-only mode 2019-05-03 02:54:57 +10:00
Makefile treewide: prefix header search paths with $(srctree)/ 2019-05-18 11:49:57 +09:00
Makefile.postlink