From 70df07838fc1c0acfab3325ae79014e241a88bdf Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Thu, 23 Nov 2023 09:58:41 +0200 Subject: [PATCH] perf header: Fix segfault on build_mem_topology() error path Do not increase the node count unless a node has been successfully read, because it can lead to a segfault if an error occurs. For example, if perf exceeds the open file limit in memory_node__read(), which, on a test system, could be made to happen by setting the file limit to exactly 32: Before: $ ulimit -n 32 $ perf mem record --all-user -- sleep 1 [ perf record: Woken up 1 times to write data ] failed: can't open memory sysfs data perf: Segmentation fault Obtained 14 stack frames. perf(sighandler_dump_stack+0x48) [0x55f4b1f59558] /lib/x86_64-linux-gnu/libc.so.6(+0x42520) [0x7f4ba1c42520] /lib/x86_64-linux-gnu/libc.so.6(free+0x1e) [0x7f4ba1ca53fe] perf(+0x178ff4) [0x55f4b1f48ff4] perf(+0x179a70) [0x55f4b1f49a70] perf(+0x17ef5d) [0x55f4b1f4ef5d] perf(+0x85c0b) [0x55f4b1e55c0b] perf(cmd_record+0xe1d) [0x55f4b1e5920d] perf(cmd_mem+0xc96) [0x55f4b1e80e56] perf(+0x130460) [0x55f4b1f00460] perf(main+0x689) [0x55f4b1e427d9] /lib/x86_64-linux-gnu/libc.so.6(+0x29d90) [0x7f4ba1c29d90] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x80) [0x7f4ba1c29e40] perf(_start+0x25) [0x55f4b1e42a25] Segmentation fault (core dumped) $ After: $ ulimit -n 32 $ perf mem record --all-user -- sleep 1 [ perf record: Woken up 1 times to write data ] failed: can't open memory sysfs data [ perf record: Captured and wrote 0.005 MB perf.data (11 samples) ] $ Fixes: f8e502b9d1b3b197 ("perf header: Ensure bitmaps are freed") Signed-off-by: Adrian Hunter Acked-by: Ian Rogers Cc: German Gomez Cc: Ian Rogers Cc: James Clark Cc: Jiri Olsa Cc: Leo Yan Cc: Namhyung Kim Link: https://lore.kernel.org/r/20231123075848.9652-2-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/header.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 1c687b5789c0..08cc2febabde 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1444,7 +1444,9 @@ static int build_mem_topology(struct memory_node **nodesp, u64 *cntp) nodes = new_nodes; size += 4; } - ret = memory_node__read(&nodes[cnt++], idx); + ret = memory_node__read(&nodes[cnt], idx); + if (!ret) + cnt += 1; } out: closedir(dir); -- 2.20.1