From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D6B5436344; Tue, 21 Jul 2026 18:05:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657116; cv=none; b=P1XnBEi0bMT/wXpIEjNY747i5qsIy/FWS1p5+fT/X0R3kTswNefqYXLckKjkc1x7GbwJYNZj/guAsqoP50T0g2GHoh7Dy9O9IgzjhVY8wi/BliaVibh+30O4sLoWSJWVkynRIUrh1LZ94Yv1esMYXWD/ggpTLobecLjwy6ab9+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784657116; c=relaxed/simple; bh=q2/AnPrYBhkqCnW2pZJ0dkbubRsqBFwtPapiH5AjTY0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UoYj3Ik0ChggIahv/PTD341kmjD1PQYa8B3xT/sX0ZAVoLY6lgYOzwOluVfUr99p78A3DihrKQP2RH1Z0bm7UwguCCnX/KVht4imLBJelLTYv5wix9S1NFBG25zPBsMthwoVSZNRHzvAumkYP677s5Rart63ZfAmd3lPdvHb0mg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=AR5HVhjS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="AR5HVhjS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E8511F000E9; Tue, 21 Jul 2026 18:05:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784657115; bh=n6fvIJAhUQhU5Uxg+XRprnnNLJt8p/JZxpM0KIswXNE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AR5HVhjSdBoJhE8Od6X4+lbYoyPK7FgqIX3R6x+2Y+a6S3QrEcShdi6iX/OFpvrBh 92ytlFA33Nt80/RAeQBW19Vj3HF6QKtScBUY+XSi/Y9VsdAuQaZwXmpbulzN3ws/4+ 1DGc2vhdgHjFIft3TXCXxmevUI7241oi0hGe2UTo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot , Ingo Molnar , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH 6.18 0642/1611] perf sched: Fix register_pid() overflow, strcpy, and BUG_ON Date: Tue, 21 Jul 2026 17:12:38 +0200 Message-ID: <20260721152529.830992287@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arnaldo Carvalho de Melo [ Upstream commit 5949d339f5ec98752d56dcd4e36f619a59d513a5 ] register_pid() has several issues when processing untrusted perf.data: 1. Integer overflow: (pid + 1) * sizeof(struct task_desc *) can wrap to a small value on 32-bit systems when pid is large (e.g. 0x40000000), causing realloc to return a tiny buffer followed by out-of-bounds writes in the initialization loop. 2. Heap buffer overflow: strcpy(task->comm, comm) copies the untrusted comm string into a fixed 20-byte COMM_LEN buffer with no length check. 3. BUG_ON on allocation failure: perf.data is untrusted input, so allocation failures should be handled gracefully rather than killing the process. 4. Realloc of sched->tasks assigned directly back, leaking the old pointer on failure; nr_tasks incremented before the realloc, leaving corrupted state on failure. Cap pid at PID_MAX_LIMIT (4194304, matching the kernel's maximum on 64-bit), replace strcpy with strlcpy, guard against NULL comm, replace BUG_ON with NULL returns using safe realloc patterns, and add NULL checks in callers that dereference the result. Fixes: ec156764d424 ("perf sched: Import schedbench.c") Reported-by: sashiko-bot Cc: Ingo Molnar Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/builtin-sched.c | 40 ++++++++++++++++++++++++++++---------- 1 file changed, 30 insertions(+), 10 deletions(-) diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index 2600747b243184..0b245e8240f6ec 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -52,6 +52,7 @@ #define COMM_LEN 20 #define SYM_LEN 129 #define MAX_PID 1024000 +#define PID_MAX_LIMIT 4194304 /* kernel limit on 64-bit */ #define MAX_PRIO 140 static const char *cpu_list; @@ -441,17 +442,28 @@ static void add_sched_event_sleep(struct perf_sched *sched, struct task_desc *ta static struct task_desc *register_pid(struct perf_sched *sched, unsigned long pid, const char *comm) { - struct task_desc *task; + struct task_desc *task, **tasks_p; static int pid_max; + /* perf.data is untrusted — cap pid to prevent overflow in size calculations */ + if (pid >= PID_MAX_LIMIT) { + pr_err("pid %lu exceeds limit %d, skipping\n", pid, PID_MAX_LIMIT); + return NULL; + } + if (sched->pid_to_task == NULL) { if (sysctl__read_int("kernel/pid_max", &pid_max) < 0) pid_max = MAX_PID; - BUG_ON((sched->pid_to_task = calloc(pid_max, sizeof(struct task_desc *))) == NULL); + sched->pid_to_task = calloc(pid_max, sizeof(struct task_desc *)); + if (sched->pid_to_task == NULL) + return NULL; } if (pid >= (unsigned long)pid_max) { - BUG_ON((sched->pid_to_task = realloc(sched->pid_to_task, (pid + 1) * - sizeof(struct task_desc *))) == NULL); + void *p = realloc(sched->pid_to_task, (pid + 1) * sizeof(struct task_desc *)); + + if (p == NULL) + return NULL; + sched->pid_to_task = p; while (pid >= (unsigned long)pid_max) sched->pid_to_task[pid_max++] = NULL; } @@ -462,9 +474,11 @@ static struct task_desc *register_pid(struct perf_sched *sched, return task; task = zalloc(sizeof(*task)); + if (task == NULL) + return NULL; task->pid = pid; - task->nr = sched->nr_tasks; - strcpy(task->comm, comm); + if (comm) + strlcpy(task->comm, comm, sizeof(task->comm)); /* * every task starts in sleeping state - this gets ignored * if there's no wakeup pointing to this sleep state: @@ -472,10 +486,12 @@ static struct task_desc *register_pid(struct perf_sched *sched, add_sched_event_sleep(sched, task, 0); sched->pid_to_task[pid] = task; - sched->nr_tasks++; - sched->tasks = realloc(sched->tasks, sched->nr_tasks * sizeof(struct task_desc *)); - BUG_ON(!sched->tasks); - sched->tasks[task->nr] = task; + tasks_p = realloc(sched->tasks, (sched->nr_tasks + 1) * sizeof(struct task_desc *)); + if (!tasks_p) + return NULL; + sched->tasks = tasks_p; + sched->tasks[sched->nr_tasks] = task; + task->nr = sched->nr_tasks++; if (verbose > 0) printf("registered task #%ld, PID %ld (%s)\n", sched->nr_tasks, pid, comm); @@ -834,6 +850,8 @@ replay_wakeup_event(struct perf_sched *sched, waker = register_pid(sched, sample->tid, ""); wakee = register_pid(sched, pid, comm); + if (waker == NULL || wakee == NULL) + return -1; add_sched_event_wakeup(sched, waker, sample->time, wakee); return 0; @@ -875,6 +893,8 @@ static int replay_switch_event(struct perf_sched *sched, prev = register_pid(sched, prev_pid, prev_comm); next = register_pid(sched, next_pid, next_comm); + if (prev == NULL || next == NULL) + return -1; sched->cpu_last_switched[cpu] = timestamp; -- 2.53.0