Artem Savkov 5ce4164fff objtool: Fix segfault in .cold detection with -ffunction-sections
[ Upstream commit 22566c1603 ]

Because find_symbol_by_name() traverses the same lists as
read_symbols(), changing sym->name in place without copying it affects
the result of find_symbol_by_name().  In the case where a ".cold"
function precedes its parent in sec->symbol_list, it can result in a
function being considered a parent of itself. This leads to function
length being set to 0 and other consequent side-effects including a
segfault in add_switch_table().  The effects of this bug are only
visible when building with -ffunction-sections in KCFLAGS.

Fix by copying the search string instead of modifying it in place.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 13810435b9 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/910abd6b5a4945130fd44f787c24e07b9e07c8da.1542736240.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2018-12-17 09:28:50 +01:00
2018-12-13 09:18:52 +01:00
2018-12-13 09:18:54 +01:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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