From 5dc9ab15203c8ae44b5193b7259525ed60b99788 Mon Sep 17 00:00:00 2001 From: Reinette Chatre Date: Thu, 24 Oct 2024 14:18:41 -0700 Subject: [PATCH] selftests/resctrl: Protect against array overrun during iMC config parsing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 48ed4e799e8fbebae838dca404a8527763d41191 ] The MBM and MBA tests need to discover the event and umask with which to configure the performance event used to measure read memory bandwidth. This is done by parsing the /sys/bus/event_source/devices/uncore_imc_/events/cas_count_read file for each iMC instance that contains the formatted output: "event=,umask=" Parsing of cas_count_read contents is done by initializing an array of MAX_TOKENS elements with tokens (deliminated by "=,") from this file. Remove the unnecessary append of a delimiter to the string needing to be parsed. Per the strtok() man page: "delimiter bytes at the start or end of the string are ignored". This has no impact on the token placement within the array. After initialization, the actual event and umask is determined by parsing the tokens directly following the "event" and "umask" tokens respectively. Iterating through the array up to index "i < MAX_TOKENS" but then accessing index "i + 1" risks array overrun during the final iteration. Avoid array overrun by ensuring that the index used within for loop will always be valid. Fixes: 1d3f08687d76 ("selftests/resctrl: Read memory bandwidth from perf IMC counter and from resctrl file system") Signed-off-by: Reinette Chatre Reviewed-by: Ilpo Järvinen Signed-off-by: Shuah Khan Signed-off-by: Sasha Levin --- tools/testing/selftests/resctrl/resctrl_val.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c index 8c275f6b4dd7..f118f659e896 100644 --- a/tools/testing/selftests/resctrl/resctrl_val.c +++ b/tools/testing/selftests/resctrl/resctrl_val.c @@ -83,13 +83,12 @@ void get_event_and_umask(char *cas_count_cfg, int count, bool op) char *token[MAX_TOKENS]; int i = 0; - strcat(cas_count_cfg, ","); token[0] = strtok(cas_count_cfg, "=,"); for (i = 1; i < MAX_TOKENS; i++) token[i] = strtok(NULL, "=,"); - for (i = 0; i < MAX_TOKENS; i++) { + for (i = 0; i < MAX_TOKENS - 1; i++) { if (!token[i]) break; if (strcmp(token[i], "event") == 0) {