The patch below does not apply to the 5.17-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a668cc07f990d2ed19424d5c1a529521a9d1cee1 Mon Sep 17 00:00:00 2001 From: Adrian Hunter adrian.hunter@intel.com Date: Wed, 13 Apr 2022 14:42:32 +0300 Subject: [PATCH] perf tools: Fix segfault accessing sample_id xyarray

perf_evsel::sample_id is an xyarray which can cause a segfault when accessed beyond its size. e.g.

# perf record -e intel_pt// -C 1 sleep 1 Segmentation fault (core dumped) #

That is happening because a dummy event is opened to capture text poke events accross all CPUs, however the mmap logic is allocating according to the number of user_requested_cpus.

In general, perf sometimes uses the evsel cpus to open events, and sometimes the evlist user_requested_cpus. However, it is not necessary to determine which case is which because the opened event file descriptors are also in an xyarray, the size of whch can be used to correctly allocate the size of the sample_id xyarray, because there is one ID per file descriptor.

Note, in the affected code path, perf_evsel fd array is subsequently used to get the file descriptor for the mmap, so it makes sense for the xyarrays to be the same size there.

Fixes: d1a177595b3a824c ("libperf: Adopt perf_evlist__mmap()/munmap() from tools/perf") Fixes: 246eba8e9041c477 ("perf tools: Add support for PERF_RECORD_TEXT_POKE") Signed-off-by: Adrian Hunter adrian.hunter@intel.com Acked-by: Ian Rogers irogers@google.com Cc: Adrian Hunter adrian.hunter@intel.com Cc: Jiri Olsa jolsa@kernel.org Cc: stable@vger.kernel.org # 5.5+ Link: https://lore.kernel.org/r/20220413114232.26914-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c index 1b15ba13c477..a09315538a30 100644 --- a/tools/lib/perf/evlist.c +++ b/tools/lib/perf/evlist.c @@ -577,7 +577,6 @@ int perf_evlist__mmap_ops(struct perf_evlist *evlist, { struct perf_evsel *evsel; const struct perf_cpu_map *cpus = evlist->user_requested_cpus; - const struct perf_thread_map *threads = evlist->threads;

if (!ops || !ops->get || !ops->mmap) return -EINVAL; @@ -589,7 +588,7 @@ int perf_evlist__mmap_ops(struct perf_evlist *evlist, perf_evlist__for_each_entry(evlist, evsel) { if ((evsel->attr.read_format & PERF_FORMAT_ID) && evsel->sample_id == NULL && - perf_evsel__alloc_id(evsel, perf_cpu_map__nr(cpus), threads->nr) < 0) + perf_evsel__alloc_id(evsel, evsel->fd->max_x, evsel->fd->max_y) < 0) return -ENOMEM; }