[OE-core] bash: Fix CVE-2019-18276

[Richard Purdie]

On Mon, 2020-02-17 at 07:44 +0100, Andrey Zhizhikin wrote:
> On Mon, Feb 17, 2020 at 4:26 AM Phil Reid <preid at electromag.com.au>
> wrote:
> > Hi All,
> > 
> > I recently started get the following failure with bash after
> > "b348e31c93f0 bash: Fix CVE-2019-18276"
> > was applied to zeus.
> > 
> > Any thoughts?
> > 
> > 
> > NOTE: Applying patch 'bash50-001' (downloads/bash50-001)
> > NOTE: Applying patch 'bash50-002' (downloads/bash50-002)
> > NOTE: Applying patch 'bash50-003' (downloads/bash50-003)
> > NOTE: Applying patch 'bash50-004' (downloads/bash50-004)
> > NOTE: Applying patch 'bash50-005' (downloads/bash50-005)
> > NOTE: Applying patch 'bash50-006' (downloads/bash50-006)
> > NOTE: Applying patch 'bash50-007' (downloads/bash50-007)
> > NOTE: Applying patch 'execute_cmd.patch' (layers/openembedded-
> > core/meta/recipes-extended/bash/bash/execute_cmd.patch)
> > NOTE: Applying patch 'mkbuiltins_have_stringize.patch'
> > (layers/openembedded-core/meta/recipes-
> > extended/bash/bash/mkbuiltins_have_stringize.patch)
> > NOTE: Applying patch 'build-tests.patch' (layers/openembedded-
> > core/meta/recipes-extended/bash/bash/build-tests.patch)
> > NOTE: Applying patch 'test-output.patch' (layers/openembedded-
> > core/meta/recipes-extended/bash/bash/test-output.patch)
> > NOTE: Applying patch 'fix-run-builtins.patch' (layers/openembedded-
> > core/meta/recipes-extended/bash/bash/fix-run-builtins.patch)
> > NOTE: Applying patch 'bash-CVE-2019-18276.patch'
> > (layers/openembedded-core/meta/recipes-extended/bash/bash/bash-CVE-
> > 2019-18276.patch)
> > ERROR: Command Error: 'quilt --quiltrc
> > /home/preid/dev/linux/v2019.11/tmp-glibc/work/cortexa9t2hf-neon-
> > emit-linux-gnueabi/bash/5.0-r0/recipe-sysroot-native/etc/quiltrc
> > push' exited with 0  Output:
> > Applying patch bash-CVE-2019-18276.patch
> > patching file MANIFEST
> > patching file bashline.c
> > patching file builtins/help.def
> > patching file config.h.in
> > patching file configure
> > Hunk #1 FAILED at 10281.
> > 1 out of 1 hunk FAILED -- rejects in file configure
> > patching file configure.ac
> > patching file doc/bash.1
> > patching file doc/bashref.texi
> > patching file lib/glob/glob.c
> > patching file pathexp.c
> > patching file shell.c
> > patching file tests/glob.tests
> > patching file tests/glob6.sub
> > patching file tests/glob7.sub
> > Patch bash-CVE-2019-18276.patch does not apply (enforce with -f)
> > DEBUG: Python function patch_do_patch finished
> > DEBUG: Python function do_patch finished
> 
> Had the same issue the day before, re-building bash clean solved it.
> At first I wanted to report it as well, but then after I tried "-c
> cleanall" - the issue was gone.
> 
> Try to do a clean build of bash and see if it is still reproducible.

I think I understand what happens here. When you do a rebuild, bitbake
tries to pop off all the old patches, then apply the new ones.

In this case its patching configure which we rebuild. It therefore
can't apply the new patch to configure since its changed by the
do_configure task.

The fix is to remove the configure change from the patch since we just
need the configure.ac piece.

Cheers,

Richard