** Changed in: linux-snapdragon (Ubuntu)
Status: New => Invalid
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https://bugs.launchpad.net/bugs/1556141
Title:
s390/mm: four page table levels vs. fork
Status in linux package in Ubuntu:
Fix Released
Status in linux-snapdragon package in Ubuntu:
Invalid
Status in linux-armadaxp source package in Precise:
Invalid
Status in linux-flo source package in Precise:
Invalid
Status in linux-goldfish source package in Precise:
Invalid
Status in linux-lts-quantal source package in Precise:
Invalid
Status in linux-lts-raring source package in Precise:
Invalid
Status in linux-lts-saucy source package in Precise:
Invalid
Status in linux-lts-trusty source package in Precise:
Invalid
Status in linux-lts-utopic source package in Precise:
Invalid
Status in linux-lts-vivid source package in Precise:
Invalid
Status in linux-lts-wily source package in Precise:
Invalid
Status in linux-lts-xenial source package in Precise:
Invalid
Status in linux-mako source package in Precise:
Invalid
Status in linux-manta source package in Precise:
Invalid
Status in linux-raspi2 source package in Precise:
Invalid
Status in linux-ti-omap4 source package in Precise:
Invalid
Status in linux-armadaxp source package in Trusty:
Invalid
Status in linux-flo source package in Trusty:
Invalid
Status in linux-goldfish source package in Trusty:
Invalid
Status in linux-lts-quantal source package in Trusty:
Invalid
Status in linux-lts-raring source package in Trusty:
Invalid
Status in linux-lts-saucy source package in Trusty:
Invalid
Status in linux-lts-trusty source package in Trusty:
Invalid
Status in linux-lts-utopic source package in Trusty:
Invalid
Status in linux-lts-vivid source package in Trusty:
Invalid
Status in linux-lts-wily source package in Trusty:
Invalid
Status in linux-lts-xenial source package in Trusty:
Fix Released
Status in linux-mako source package in Trusty:
Invalid
Status in linux-manta source package in Trusty:
Invalid
Status in linux-raspi2 source package in Trusty:
Invalid
Status in linux-ti-omap4 source package in Trusty:
Invalid
Status in linux-armadaxp source package in Wily:
Invalid
Status in linux-flo source package in Wily:
Invalid
Status in linux-goldfish source package in Wily:
Invalid
Status in linux-lts-quantal source package in Wily:
Invalid
Status in linux-lts-raring source package in Wily:
Invalid
Status in linux-lts-saucy source package in Wily:
Invalid
Status in linux-lts-trusty source package in Wily:
Invalid
Status in linux-lts-utopic source package in Wily:
Invalid
Status in linux-lts-vivid source package in Wily:
Invalid
Status in linux-lts-wily source package in Wily:
Invalid
Status in linux-lts-xenial source package in Wily:
Invalid
Status in linux-mako source package in Wily:
Invalid
Status in linux-manta source package in Wily:
Invalid
Status in linux-raspi2 source package in Wily:
Invalid
Status in linux-ti-omap4 source package in Wily:
Invalid
Status in linux source package in Xenial:
Fix Released
Status in linux-armadaxp source package in Xenial:
Invalid
Status in linux-flo source package in Xenial:
Invalid
Status in linux-goldfish source package in Xenial:
Invalid
Status in linux-lts-quantal source package in Xenial:
Invalid
Status in linux-lts-raring source package in Xenial:
Invalid
Status in linux-lts-saucy source package in Xenial:
Invalid
Status in linux-lts-trusty source package in Xenial:
Invalid
Status in linux-lts-utopic source package in Xenial:
Invalid
Status in linux-lts-vivid source package in Xenial:
Invalid
Status in linux-lts-wily source package in Xenial:
Invalid
Status in linux-lts-xenial source package in Xenial:
Invalid
Status in linux-mako source package in Xenial:
Invalid
Status in linux-manta source package in Xenial:
Invalid
Status in linux-raspi2 source package in Xenial:
Invalid
Status in linux-snapdragon source package in Xenial:
Invalid
Status in linux-ti-omap4 source package in Xenial:
Invalid
Bug description:
== Comment: #0 - Hendrik Brueckner <brueck...@de.ibm.com> - 2016-03-11
08:30:57 ==
Please backport:
http://git.kernel.org/cgit/linux/kernel/git/s390/linux.git/commit/?h
=for-linus&id=3446c13b268af86391d06611327006b059b8bab1
s390/mm: four page table levels vs. fork
The fork of a process with four page table levels is broken since
git commit 6252d702c5311ce9 "[S390] dynamic page tables."
All new mm contexts are created with three page table levels and
an asce limit of 4TB. If the parent has four levels dup_mmap will
add vmas to the new context which are outside of the asce limit.
The subsequent call to copy_page_range will walk the three level
page table structure of the new process with non-zero pgd and pud
indexes. This leads to memory clobbers as the pgd_index *and* the
pud_index is added to the mm->pgd pointer without a pgd_deref
in between.
The init_new_context() function is selecting the number of page
table levels for a new context. The function is used by mm_init()
which in turn is called by dup_mm() and mm_alloc(). These two are
used by fork() and exec(). The init_new_context() function can
distinguish the two cases by looking at mm->context.asce_limit,
for fork() the mm struct has been copied and the number of page
table levels may not change. For exec() the mm_alloc() function
set the new mm structure to zero, in this case a three-level page
table is created as the temporary stack space is located at
STACK_TOP_MAX = 4TB.
This fixes CVE-2016-2143.
Reported-by: Marcin Ko?cielnicki <koria...@0x04.net>
Reviewed-by: Heiko Carstens <heiko.carst...@de.ibm.com>
Cc: sta...@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidef...@de.ibm.com>
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