84 lines
2.5 KiB
Diff
84 lines
2.5 KiB
Diff
From 72450627ba8a173366265af550115de951f148c9 Mon Sep 17 00:00:00 2001
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From: Andreas Schwab <schwab@suse.de>
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Date: Thu, 18 Aug 2016 11:38:28 +0200
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Subject: [PATCH 09] arm: mark __startcontext as .cantunwind (bug 20435)
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__startcontext marks the bottom of the call stack of the contexts created
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by makecontext.
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(cherry picked from commit 9e2ff6c9cc54c0b4402b8d49e4abe7000fde7617)
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Also includes the NEWS update, cherry-picked from commits
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056dd72af83f5459ce6d545a49dea6dba7d635dc and
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4d047efdbc55b0d68947cde682e5363d16a66294.
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---
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ChangeLog | 6 ++++++
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NEWS | 11 +++++++++++
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sysdeps/unix/sysv/linux/arm/setcontext.S | 7 +++++++
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3 files changed, 24 insertions(+)
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diff --git a/ChangeLog b/ChangeLog
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index 9dfd24d..734e34b 100644
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--- a/ChangeLog
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+++ b/ChangeLog
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@@ -1,3 +1,9 @@
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+2016-08-15 Andreas Schwab <schwab@suse.de>
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+
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+ [BZ #20435]
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+ * sysdeps/unix/sysv/linux/arm/setcontext.S (__startcontext): Mark
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+ as .cantunwind.
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+
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2016-08-17 Florian Weimer <fweimer@redhat.com>
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[BZ #20452]
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diff --git a/NEWS b/NEWS
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index b0447e7..4a042db 100644
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--- a/NEWS
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+++ b/NEWS
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@@ -5,6 +5,17 @@ See the end for copying conditions.
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Please send GNU C library bug reports via <http://sourceware.org/bugzilla/>
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using `glibc' in the "product" field.
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+Version 2.24.1
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+
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+Security related changes:
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+
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+* On ARM EABI (32-bit), generating a backtrace for execution contexts which
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+ have been created with makecontext could fail to terminate due to a
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+ missing .cantunwind annotation. This has been observed to lead to a hang
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+ (denial of service) in some Go applications compiled with gccgo. Reported
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+ by Andreas Schwab. (CVE-2016-6323)
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+
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+
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Version 2.24
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* The minimum Linux kernel version that this version of the GNU C Library
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diff --git a/sysdeps/unix/sysv/linux/arm/setcontext.S b/sysdeps/unix/sysv/linux/arm/setcontext.S
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index 603e508..d1f168f 100644
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--- a/sysdeps/unix/sysv/linux/arm/setcontext.S
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+++ b/sysdeps/unix/sysv/linux/arm/setcontext.S
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@@ -86,12 +86,19 @@ weak_alias(__setcontext, setcontext)
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/* Called when a makecontext() context returns. Start the
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context in R4 or fall through to exit(). */
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+ /* Unwind descriptors are looked up based on PC - 2, so we have to
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+ make sure to mark the instruction preceding the __startcontext
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+ label as .cantunwind. */
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+ .fnstart
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+ .cantunwind
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+ nop
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ENTRY(__startcontext)
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movs r0, r4
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bne PLTJMP(__setcontext)
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@ New context was 0 - exit
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b PLTJMP(HIDDEN_JUMPTARGET(exit))
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+ .fnend
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END(__startcontext)
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#ifdef PIC
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--
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2.7.4.GIT
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