Revision 73223e4e2e3867ebf033a5a8eb2e5df0158ccc99 authored by zhong jiang on 18 August 2017, 22:16:24 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:02 UTC
I hit a use after free issue when executing trinity and repoduced it
with KASAN enabled.  The related call trace is as follows.

  BUG: KASan: use after free in SyS_get_mempolicy+0x3c8/0x960 at addr ffff8801f582d766
  Read of size 2 by task syz-executor1/798

  INFO: Allocated in mpol_new.part.2+0x74/0x160 age=3 cpu=1 pid=799
     __slab_alloc+0x768/0x970
     kmem_cache_alloc+0x2e7/0x450
     mpol_new.part.2+0x74/0x160
     mpol_new+0x66/0x80
     SyS_mbind+0x267/0x9f0
     system_call_fastpath+0x16/0x1b
  INFO: Freed in __mpol_put+0x2b/0x40 age=4 cpu=1 pid=799
     __slab_free+0x495/0x8e0
     kmem_cache_free+0x2f3/0x4c0
     __mpol_put+0x2b/0x40
     SyS_mbind+0x383/0x9f0
     system_call_fastpath+0x16/0x1b
  INFO: Slab 0xffffea0009cb8dc0 objects=23 used=8 fp=0xffff8801f582de40 flags=0x200000000004080
  INFO: Object 0xffff8801f582d760 @offset=5984 fp=0xffff8801f582d600

  Bytes b4 ffff8801f582d750: ae 01 ff ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a  ........ZZZZZZZZ
  Object ffff8801f582d760: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
  Object ffff8801f582d770: 6b 6b 6b 6b 6b 6b 6b a5                          kkkkkkk.
  Redzone ffff8801f582d778: bb bb bb bb bb bb bb bb                          ........
  Padding ffff8801f582d8b8: 5a 5a 5a 5a 5a 5a 5a 5a                          ZZZZZZZZ
  Memory state around the buggy address:
  ffff8801f582d600: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8801f582d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  >ffff8801f582d700: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fc

!shared memory policy is not protected against parallel removal by other
thread which is normally protected by the mmap_sem.  do_get_mempolicy,
however, drops the lock midway while we can still access it later.

Early premature up_read is a historical artifact from times when
put_user was called in this path see https://lwn.net/Articles/124754/
but that is gone since 8bccd85ffbaf ("[PATCH] Implement sys_* do_*
layering in the memory policy layer.").  but when we have the the
current mempolicy ref count model.  The issue was introduced
accordingly.

Fix the issue by removing the premature release.

Link: http://lkml.kernel.org/r/1502950924-27521-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>	[2.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent da094e4
Raw File
Makefile
# -*- makefile -*-
# Makefile for Sphinx documentation
#

subdir-y :=

# You can set these variables from the command line.
SPHINXBUILD   = sphinx-build
SPHINXOPTS    =
SPHINXDIRS    = .
_SPHINXDIRS   = $(patsubst $(srctree)/Documentation/%/conf.py,%,$(wildcard $(srctree)/Documentation/*/conf.py))
SPHINX_CONF   = conf.py
PAPER         =
BUILDDIR      = $(obj)/output
PDFLATEX      = xelatex
LATEXOPTS     = -interaction=batchmode

# User-friendly check for sphinx-build
HAVE_SPHINX := $(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi)

ifeq ($(HAVE_SPHINX),0)

.DEFAULT:
	$(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.)
	@echo "  SKIP    Sphinx $@ target."

else # HAVE_SPHINX

# User-friendly check for pdflatex
HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi)

# Internal variables.
PAPEROPT_a4     = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
KERNELDOC       = $(srctree)/scripts/kernel-doc
KERNELDOC_CONF  = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC)
ALLSPHINXOPTS   =  $(KERNELDOC_CONF) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS)
# the i18n builder cannot share the environment and doctrees with the others
I18NSPHINXOPTS  = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .

# commands; the 'cmd' from scripts/Kbuild.include is not *loopable*
loop_cmd = $(echo-cmd) $(cmd_$(1)) || exit;

# $2 sphinx builder e.g. "html"
# $3 name of the build subfolder / e.g. "media", used as:
#    * dest folder relative to $(BUILDDIR) and
#    * cache folder relative to $(BUILDDIR)/.doctrees
# $4 dest subfolder e.g. "man" for man pages at media/man
# $5 reST source folder relative to $(srctree)/$(src),
#    e.g. "media" for the linux-tv book-set at ./Documentation/media

quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
      cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media $2 && \
	PYTHONDONTWRITEBYTECODE=1 \
	BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
	$(SPHINXBUILD) \
	-b $2 \
	-c $(abspath $(srctree)/$(src)) \
	-d $(abspath $(BUILDDIR)/.doctrees/$3) \
	-D version=$(KERNELVERSION) -D release=$(KERNELRELEASE) \
	$(ALLSPHINXOPTS) \
	$(abspath $(srctree)/$(src)/$5) \
	$(abspath $(BUILDDIR)/$3/$4)

htmldocs:
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))

linkcheckdocs:
	@$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var)))

latexdocs:
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var)))

ifeq ($(HAVE_PDFLATEX),0)

pdfdocs:
	$(warning The '$(PDFLATEX)' command was not found. Make sure you have it installed and in PATH to produce PDF output.)
	@echo "  SKIP    Sphinx $@ target."

else # HAVE_PDFLATEX

pdfdocs: latexdocs
	$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX=$(PDFLATEX) LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;)

endif # HAVE_PDFLATEX

epubdocs:
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var)))

xmldocs:
	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var)))

endif # HAVE_SPHINX

# The following targets are independent of HAVE_SPHINX, and the rules should
# work or silently pass without Sphinx.

# no-ops for the Sphinx toolchain
sgmldocs:
	@:
psdocs:
	@:
mandocs:
	@:
installmandocs:
	@:

cleandocs:
	$(Q)rm -rf $(BUILDDIR)
	$(Q)$(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media clean

dochelp:
	@echo  ' Linux kernel internal documentation in different formats from ReST:'
	@echo  '  htmldocs        - HTML'
	@echo  '  latexdocs       - LaTeX'
	@echo  '  pdfdocs         - PDF'
	@echo  '  epubdocs        - EPUB'
	@echo  '  xmldocs         - XML'
	@echo  '  linkcheckdocs   - check for broken external links (will connect to external hosts)'
	@echo  '  cleandocs       - clean all generated files'
	@echo
	@echo  '  make SPHINXDIRS="s1 s2" [target] Generate only docs of folder s1, s2'
	@echo  '  valid values for SPHINXDIRS are: $(_SPHINXDIRS)'
	@echo
	@echo  '  make SPHINX_CONF={conf-file} [target] use *additional* sphinx-build'
	@echo  '  configuration. This is e.g. useful to build with nit-picking config.'
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