From: Ian Rogers Date: Wed, 6 May 2026 04:10:04 +0000 (-0700) Subject: perf sched stats: Fix segmentation faults, memory leaks, and stale pointers in diff... X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=111388a0c01e6c2f9822623a764b3dcf8bc1492c;p=thirdparty%2Flinux.git perf sched stats: Fix segmentation faults, memory leaks, and stale pointers in diff mode The patch addresses multiple segmentation fault vectors, out-of-bounds reads, and memory leaks in perf sched stats by adding bounds checks, NULL checks, proper error propagation, and robust memory cleanup. 1. In get_all_cpu_stats(), added assert(!list_empty(head)) to prevent unsafe list_first_entry() calls on empty lists, added a missing NULL check for summary_head->cpu_data allocation, and implemented a cleanup ladder using a temporary list to prevent memory leaks on error paths. 2. In free_schedstat(), fixed memory leaks by ensuring internal domain_data and cpu_data pointers are freed. 3. In show_schedstat_data(), fixed a stale pointer issue where ds2 retained its value from a previous iteration when dptr2 became NULL, and added proper propagation of errors from get_all_cpu_stats(). 4. Propagated show_schedstat_data() errors up to perf_sched__schedstat_diff() and perf_sched__schedstat_live() to prevent output corruption on failure. 5. In show_schedstat_data(), added NULL checks for cd_map1 and cd_map2 to gracefully handle invalid or empty data files. 6. Added parallel iteration termination checks using list_is_last() in show_schedstat_data() for both domain and CPU lists to safely terminate at the end of each list when files contain a different number of CPUs or domains. 7. Added CPU bounds checks (cs1->cpu >= nr1 and cs2->cpu >= nr2) in show_schedstat_data() to prevent out-of-bounds reads from cd_map1 and cd_map2 when comparing files from machines with different CPU counts. 8. Added NULL checks for cd_info1 and cd_info2 to prevent crashes when a CPU has data samples but no corresponding domain info in the header. 9. Added domain bounds checks (ds1->domain >= cd_info1->nr_domains and ds2->domain >= cd_info2->nr_domains) to prevent out-of-bounds array accesses in the domains array. 10. Added NULL checks for dinfo1 and dinfo2 in show_schedstat_data() to prevent crashes when a domain has no corresponding domain info. 11. Zero-initialized the perf_data array in perf_sched__schedstat_diff() to prevent stack garbage from causing perf_data_file__fd() to attempt to use a NULL fptr when use_stdio happened to be non-zero. Assisted-by: Gemini:gemini-3.1-pro-preview Reviewed-by: James Clark Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Athira Rajeev Cc: Ingo Molnar Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Venkat Rao Bagalkote Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index 555247568e7a6..fd679b106582a 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -3947,6 +3947,8 @@ static struct schedstat_domain *domain_second_pass; static bool after_workload_flag; static bool verbose_field; +static void free_schedstat(struct list_head *head); + static void store_schedstat_cpu_diff(struct schedstat_cpu *after_workload) { struct perf_record_schedstat_cpu *before = cpu_second_pass->cpu_data; @@ -4170,37 +4172,50 @@ static void summarize_schedstat_domain(struct schedstat_domain *summary_domain, */ static int get_all_cpu_stats(struct list_head *head) { - struct schedstat_cpu *cptr = list_first_entry(head, struct schedstat_cpu, cpu_list); - struct schedstat_cpu *summary_head = NULL; - struct perf_record_schedstat_domain *ds; - struct perf_record_schedstat_cpu *cs; + struct schedstat_cpu *cptr, *summary_head = NULL; struct schedstat_domain *dptr, *tdptr; bool is_last = false; int cnt = 1; int ret = 0; + struct list_head tmp_cleanup_list; - if (cptr) { - summary_head = zalloc(sizeof(*summary_head)); - if (!summary_head) - return -ENOMEM; + assert(!list_empty(head)); + cptr = list_first_entry(head, struct schedstat_cpu, cpu_list); - summary_head->cpu_data = zalloc(sizeof(*cs)); - memcpy(summary_head->cpu_data, cptr->cpu_data, sizeof(*cs)); + INIT_LIST_HEAD(&tmp_cleanup_list); - INIT_LIST_HEAD(&summary_head->domain_head); + summary_head = zalloc(sizeof(*summary_head)); + if (!summary_head) + return -ENOMEM; - list_for_each_entry(dptr, &cptr->domain_head, domain_list) { - tdptr = zalloc(sizeof(*tdptr)); - if (!tdptr) - return -ENOMEM; + INIT_LIST_HEAD(&summary_head->domain_head); + INIT_LIST_HEAD(&summary_head->cpu_list); + list_add(&summary_head->cpu_list, &tmp_cleanup_list); - tdptr->domain_data = zalloc(sizeof(*ds)); - if (!tdptr->domain_data) - return -ENOMEM; + summary_head->cpu_data = zalloc(sizeof(*summary_head->cpu_data)); + if (!summary_head->cpu_data) { + ret = -ENOMEM; + goto out_cleanup; + } + memcpy(summary_head->cpu_data, cptr->cpu_data, sizeof(*summary_head->cpu_data)); + + list_for_each_entry(dptr, &cptr->domain_head, domain_list) { + tdptr = zalloc(sizeof(*tdptr)); + if (!tdptr) { + ret = -ENOMEM; + goto out_cleanup; + } + INIT_LIST_HEAD(&tdptr->domain_list); - memcpy(tdptr->domain_data, dptr->domain_data, sizeof(*ds)); - list_add_tail(&tdptr->domain_list, &summary_head->domain_head); + tdptr->domain_data = zalloc(sizeof(*tdptr->domain_data)); + if (!tdptr->domain_data) { + free(tdptr); + ret = -ENOMEM; + goto out_cleanup; } + + memcpy(tdptr->domain_data, dptr->domain_data, sizeof(*tdptr->domain_data)); + list_add_tail(&tdptr->domain_list, &summary_head->domain_head); } list_for_each_entry(cptr, head, cpu_list) { @@ -4212,32 +4227,52 @@ static int get_all_cpu_stats(struct list_head *head) cnt++; summarize_schedstat_cpu(summary_head, cptr, cnt, is_last); + if (list_empty(&summary_head->domain_head)) + continue; + tdptr = list_first_entry(&summary_head->domain_head, struct schedstat_domain, domain_list); list_for_each_entry(dptr, &cptr->domain_head, domain_list) { summarize_schedstat_domain(tdptr, dptr, cnt, is_last); + if (list_is_last(&tdptr->domain_list, &summary_head->domain_head)) { + tdptr = NULL; + break; + } tdptr = list_next_entry(tdptr, domain_list); } } + list_del_init(&summary_head->cpu_list); list_add(&summary_head->cpu_list, head); + return 0; + +out_cleanup: + free_schedstat(&tmp_cleanup_list); return ret; } -static int show_schedstat_data(struct list_head *head1, struct cpu_domain_map **cd_map1, - struct list_head *head2, struct cpu_domain_map **cd_map2, +static int show_schedstat_data(struct list_head *head1, struct cpu_domain_map **cd_map1, int nr1, + struct list_head *head2, struct cpu_domain_map **cd_map2, int nr2, bool summary_only) { struct schedstat_cpu *cptr1 = list_first_entry(head1, struct schedstat_cpu, cpu_list); struct perf_record_schedstat_domain *ds1 = NULL, *ds2 = NULL; - struct perf_record_schedstat_cpu *cs1 = NULL, *cs2 = NULL; struct schedstat_domain *dptr1 = NULL, *dptr2 = NULL; struct schedstat_cpu *cptr2 = NULL; __u64 jiffies1 = 0, jiffies2 = 0; bool is_summary = true; int ret = 0; + if (!cd_map1) { + pr_err("Error: CPU domain map 1 is missing.\n"); + return -1; + } + if (head2 && !cd_map2) { + pr_err("Error: CPU domain map 2 is missing.\n"); + return -1; + } + printf("Description\n"); print_separator2(SEP_LEN, "", 0); printf("%-30s-> %s\n", "DESC", "Description of the field"); @@ -4260,21 +4295,47 @@ static int show_schedstat_data(struct list_head *head1, struct cpu_domain_map ** printf("\n"); ret = get_all_cpu_stats(head1); + if (ret) + return ret; if (cptr2) { ret = get_all_cpu_stats(head2); + if (ret) + return ret; cptr2 = list_first_entry(head2, struct schedstat_cpu, cpu_list); } list_for_each_entry(cptr1, head1, cpu_list) { struct cpu_domain_map *cd_info1 = NULL, *cd_info2 = NULL; + struct perf_record_schedstat_cpu *cs1 = cptr1->cpu_data; + struct perf_record_schedstat_cpu *cs2 = NULL; - cs1 = cptr1->cpu_data; + dptr2 = NULL; + if (cs1->cpu >= (u32)nr1) { + pr_err("Error: CPU %d exceeds domain map size %d\n", cs1->cpu, nr1); + return -1; + } cd_info1 = cd_map1[cs1->cpu]; + if (!cd_info1) { + pr_err("Error: CPU %d domain info is missing in map 1.\n", + cs1->cpu); + return -1; + } if (cptr2) { cs2 = cptr2->cpu_data; + if (cs2->cpu >= (u32)nr2) { + pr_err("Error: CPU %d exceeds domain map size %d\n", cs2->cpu, nr2); + return -1; + } cd_info2 = cd_map2[cs2->cpu]; - dptr2 = list_first_entry(&cptr2->domain_head, struct schedstat_domain, - domain_list); + if (!cd_info2) { + pr_err("Error: CPU %d domain info is missing in map 2.\n", + cs2->cpu); + return -1; + } + if (!list_empty(&cptr2->domain_head)) + dptr2 = list_first_entry(&cptr2->domain_head, + struct schedstat_domain, + domain_list); } if (cs2 && cs1->cpu != cs2->cpu) { @@ -4302,10 +4363,31 @@ static int show_schedstat_data(struct list_head *head1, struct cpu_domain_map ** struct domain_info *dinfo1 = NULL, *dinfo2 = NULL; ds1 = dptr1->domain_data; + ds2 = NULL; + if (ds1->domain >= cd_info1->nr_domains) { + pr_err("Error: Domain %d exceeds max domains %d for CPU %d in map 1.\n", + ds1->domain, cd_info1->nr_domains, cs1->cpu); + return -1; + } dinfo1 = cd_info1->domains[ds1->domain]; + if (!dinfo1) { + pr_err("Error: Domain %d info is missing for CPU %d in map 1.\n", + ds1->domain, cs1->cpu); + return -1; + } if (dptr2) { ds2 = dptr2->domain_data; + if (ds2->domain >= cd_info2->nr_domains) { + pr_err("Error: Domain %d exceeds max domains %d for CPU %d in map 2.\n", + ds2->domain, cd_info2->nr_domains, cs2->cpu); + return -1; + } dinfo2 = cd_info2->domains[ds2->domain]; + if (!dinfo2) { + pr_err("Error: Domain %d info is missing for CPU %d in map 2.\n", + ds2->domain, cs2->cpu); + return -1; + } } if (dinfo2 && dinfo1->domain != dinfo2->domain) { @@ -4334,14 +4416,22 @@ static int show_schedstat_data(struct list_head *head1, struct cpu_domain_map ** print_domain_stats(ds1, ds2, jiffies1, jiffies2); print_separator2(SEP_LEN, "", 0); - if (dptr2) - dptr2 = list_next_entry(dptr2, domain_list); + if (dptr2) { + if (list_is_last(&dptr2->domain_list, &cptr2->domain_head)) + dptr2 = NULL; + else + dptr2 = list_next_entry(dptr2, domain_list); + } } if (summary_only) break; - if (cptr2) - cptr2 = list_next_entry(cptr2, cpu_list); + if (cptr2) { + if (list_is_last(&cptr2->cpu_list, head2)) + cptr2 = NULL; + else + cptr2 = list_next_entry(cptr2, cpu_list); + } is_summary = false; } @@ -4473,9 +4563,11 @@ static void free_schedstat(struct list_head *head) list_for_each_entry_safe(cptr, n2, head, cpu_list) { list_for_each_entry_safe(dptr, n1, &cptr->domain_head, domain_list) { list_del_init(&dptr->domain_list); + free(dptr->domain_data); free(dptr); } list_del_init(&cptr->cpu_list); + free(cptr->cpu_data); free(cptr); } } @@ -4523,7 +4615,9 @@ static int perf_sched__schedstat_report(struct perf_sched *sched) } cd_map = session->header.env.cpu_domain; - err = show_schedstat_data(&cpu_head, cd_map, NULL, NULL, false); + err = show_schedstat_data(&cpu_head, cd_map, + session->header.env.nr_cpus_avail, + NULL, NULL, 0, false); } out: @@ -4538,7 +4632,7 @@ static int perf_sched__schedstat_diff(struct perf_sched *sched, struct cpu_domain_map **cd_map0 = NULL, **cd_map1 = NULL; struct list_head cpu_head_ses0, cpu_head_ses1; struct perf_session *session[2]; - struct perf_data data[2]; + struct perf_data data[2] = {0}; int ret = 0, err = 0; static const char *defaults[] = { "perf.data.old", @@ -4573,8 +4667,10 @@ static int perf_sched__schedstat_diff(struct perf_sched *sched, } err = perf_session__process_events(session[0]); - if (err) + if (err) { + free_schedstat(&cpu_head); goto out_delete_ses0; + } cd_map0 = session[0]->header.env.cpu_domain; list_replace_init(&cpu_head, &cpu_head_ses0); @@ -4590,8 +4686,10 @@ static int perf_sched__schedstat_diff(struct perf_sched *sched, } err = perf_session__process_events(session[1]); - if (err) + if (err) { + free_schedstat(&cpu_head); goto out_delete_ses1; + } cd_map1 = session[1]->header.env.cpu_domain; list_replace_init(&cpu_head, &cpu_head_ses1); @@ -4607,10 +4705,13 @@ static int perf_sched__schedstat_diff(struct perf_sched *sched, if (list_empty(&cpu_head_ses0)) { pr_err("Data is not available\n"); ret = -1; - goto out_delete_ses0; + goto out_delete_ses1; } - show_schedstat_data(&cpu_head_ses0, cd_map0, &cpu_head_ses1, cd_map1, true); + ret = show_schedstat_data(&cpu_head_ses0, cd_map0, session[0]->header.env.nr_cpus_avail, + &cpu_head_ses1, cd_map1, session[1]->header.env.nr_cpus_avail, true); + if (ret) + goto out_delete_ses1; out_delete_ses1: free_schedstat(&cpu_head_ses1); @@ -4720,7 +4821,7 @@ static int perf_sched__schedstat_live(struct perf_sched *sched, goto out; } - show_schedstat_data(&cpu_head, cd_map, NULL, NULL, false); + err = show_schedstat_data(&cpu_head, cd_map, nr, NULL, NULL, 0, false); free_cpu_domain_info(cd_map, sv, nr); out: free_schedstat(&cpu_head);