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Numfor Mbiziwo-Tiapo 0a19fff567 perf header: Fix use of unitialized value warning 
[ Upstream commit 20f9781f49 ]

When building our local version of perf with MSAN (Memory Sanitizer) and
running the perf record command, MSAN throws a use of uninitialized
value warning in "tools/perf/util/util.c:333:6".

This warning stems from the "buf" variable being passed into "write".
It originated as the variable "ev" with the type union perf_event*
defined in the "perf_event__synthesize_attr" function in
"tools/perf/util/header.c".

In the "perf_event__synthesize_attr" function they allocate space with a malloc
call using ev, then go on to only assign some of the member variables before
passing "ev" on as a parameter to the "process" function therefore "ev"
contains uninitialized memory. Changing the malloc call to zalloc to initialize
all the members of "ev" which gets rid of the warning.

To reproduce this warning, build perf by running:
make -C tools/perf CLANG=1 CC=clang EXTRA_CFLAGS="-fsanitize=memory\
 -fsanitize-memory-track-origins"

(Additionally, llvm might have to be installed and clang might have to
be specified as the compiler - export CC=/usr/bin/clang)

then running:
tools/perf/perf record -o - ls / | tools/perf/perf --no-pager annotate\
 -i - --stdio

Please see the cover letter for why false positive warnings may be
generated.

Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Drayton <mbd@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20190724234500.253358-2-nums@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-08-25 10:47:53 +02:00
arch riscv: Make __fstate_clean() work correctly. 2019-08-25 10:47:51 +02:00
block block, scsi: Change the preempt-only flag into a counter 2019-08-04 09:30:57 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: chacha20poly1305 - fix atomic sleep when using async algorithm 2019-07-26 09:14:19 +02:00
Documentation Documentation: Add swapgs description to the Spectre v1 documentation 2019-08-06 19:06:58 +02:00
drivers irqchip/irq-imx-gpcv2: Forward irq type to parent 2019-08-25 10:47:53 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs seq_file: fix problem when seeking mid-record 2019-08-25 10:47:43 +02:00
include KVM: Fix leak vCPU's VMCS value into other pCPU 2019-08-16 10:12:53 +02:00
init initramfs: free initrd memory if opening /initrd.image fails 2019-06-15 11:54:01 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel cpufreq: schedutil: Don't skip freq update when limits change 2019-08-25 10:47:46 +02:00
lib test_firmware: fix a memory leak bug 2019-08-16 10:12:49 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/usercopy: use memory range to be accessed for wraparound check 2019-08-25 10:47:44 +02:00
net netfilter: ebtables: also count base chain policies 2019-08-25 10:47:50 +02:00
samples samples, bpf: suppress compiler warning 2019-07-14 08:11:04 +02:00
scripts scripts/sphinx-pre-install: fix script for RHEL/CentOS 2019-08-16 10:12:44 +02:00
security selinux: fix memory leak in policydb_init() 2019-08-06 19:06:54 +02:00
sound ALSA: hda - Let all conexant codec enter D3 when rebooting 2019-08-25 10:47:48 +02:00
tools perf header: Fix use of unitialized value warning 2019-08-25 10:47:53 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: Fix leak vCPU's VMCS value into other pCPU 2019-08-16 10:12:53 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile Linux 4.19.67 2019-08-16 10:12:54 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

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.