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* [Bug nptl/26691] New: Use a minimum guard size of 64 KiB on aarch64
@ 2020-10-01 12:29 fweimer at redhat dot com
2020-10-02 9:00 ` [Bug nptl/26691] " cvs-commit at gcc dot gnu.org
2020-10-02 9:47 ` fweimer at redhat dot com
0 siblings, 2 replies; 3+ messages in thread
From: fweimer at redhat dot com @ 2020-10-01 12:29 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26691
Bug ID: 26691
Summary: Use a minimum guard size of 64 KiB on aarch64
Product: glibc
Version: 2.33
Status: NEW
Severity: normal
Priority: P2
Component: nptl
Assignee: unassigned at sourceware dot org
Reporter: fweimer at redhat dot com
CC: drepper.fsp at gmail dot com
Target Milestone: ---
Target: aarch64
On aarch64, the -fstack-clash-protection implementation in GCC only issues
probes with a 64 KiB interval, so for full protection, it is necessary to have
a guard region of at least that size.
For the main thread, the kernel sets up the guard region, but for threads
created using pthread_create, glibc has to do this.
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* [Bug nptl/26691] Use a minimum guard size of 64 KiB on aarch64
2020-10-01 12:29 [Bug nptl/26691] New: Use a minimum guard size of 64 KiB on aarch64 fweimer at redhat dot com
@ 2020-10-02 9:00 ` cvs-commit at gcc dot gnu.org
2020-10-02 9:47 ` fweimer at redhat dot com
1 sibling, 0 replies; 3+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2020-10-02 9:00 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26691
--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Szabolcs Nagy <nsz@sourceware.org>:
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=238032ead6f34c41542890b968d973eb5c839673
commit 238032ead6f34c41542890b968d973eb5c839673
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Wed Dec 13 15:50:21 2017 +0000
aarch64: enforce >=64K guard size [BZ #26691]
There are several compiler implementations that allow large stack
allocations to jump over the guard page at the end of the stack and
corrupt memory beyond that. See CVE-2017-1000364.
Compilers can emit code to probe the stack such that the guard page
cannot be skipped, but on aarch64 the probe interval is 64K by default
instead of the minimum supported page size (4K).
This patch enforces at least 64K guard on aarch64 unless the guard
is disabled by setting its size to 0. For backward compatibility
reasons the increased guard is not reported, so it is only observable
by exhausting the address space or parsing /proc/self/maps on linux.
On other targets the patch has no effect. If the stack probe interval
is larger than a page size on a target then ARCH_MIN_GUARD_SIZE can
be defined to get large enough stack guard on libc allocated stacks.
The patch does not affect threads with user allocated stacks.
Fixes bug 26691.
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* [Bug nptl/26691] Use a minimum guard size of 64 KiB on aarch64
2020-10-01 12:29 [Bug nptl/26691] New: Use a minimum guard size of 64 KiB on aarch64 fweimer at redhat dot com
2020-10-02 9:00 ` [Bug nptl/26691] " cvs-commit at gcc dot gnu.org
@ 2020-10-02 9:47 ` fweimer at redhat dot com
1 sibling, 0 replies; 3+ messages in thread
From: fweimer at redhat dot com @ 2020-10-02 9:47 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=26691
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
CC| |fweimer at redhat dot com
Target Milestone|--- |2.33
--- Comment #2 from Florian Weimer <fweimer at redhat dot com> ---
Fixed for glibc 2.33.
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2020-10-01 12:29 [Bug nptl/26691] New: Use a minimum guard size of 64 KiB on aarch64 fweimer at redhat dot com
2020-10-02 9:00 ` [Bug nptl/26691] " cvs-commit at gcc dot gnu.org
2020-10-02 9:47 ` fweimer at redhat dot com
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