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 8B9543AB48F; Tue, 21 Jul 2026 19:00:54 +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=1784660489; cv=none; b=brn6T3kW44OqWnjNHr4ROpJbIghZeYLuPP3rK4G9HNemY2l/I68jN7rbotGhYVUteFJasb0MTYeP581BtoiELWFMkdIDbtVky4iPy/yLnBdlZWTR7FRyMc2tPyLWnQEFM7lTAOOW3aVe/0Af3Te7EFlSotH4tImUsR/hfpSvMvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784660489; c=relaxed/simple; bh=avZcO66o4K7zVu1uydKfOTk87dzYyU9dTeySkans+VA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jvVELMo7fNSEBvHiGGw9h7rVakMESCMgJRaFyuyJGCUSE3+QC2cZ8ZZ3dM2Wq5dIuN7GIzmePJHk4zKbcW91UngyvKdvzC88UWbmKhetBZx72i2F0rjCjE8BwhufaEyzfZk+h95aB9mqEuNRjEIk4TGnspByOhxKd6DsKz9tzkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VNXE0sI+; 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="VNXE0sI+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 379701F00ACF; Tue, 21 Jul 2026 19:00:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784660438; bh=rteXlTNmzXzVpl2+DUwnAEUGsT9U4UoKyfQpom+Ygdg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VNXE0sI+xLuDgCdqDCqDNGyrnfcCjqp8Np4/x7INAWGjyFlJkMgkcDRrBUMBG6LBM RWirSip+Y7TJE5a5ZCAtqiCh2ch4obRmwQKR//NrcCmM03xUDs+v0mn0Gs8Z6Zqey4 F7GQ3zJitaNj/5pI50WU+4benUb0SuQgXJm95u2s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot , Ian Rogers , Don Zickus , Arnaldo Carvalho de Melo , Sasha Levin Subject: [PATCH 7.1 0981/2077] perf tools: Fix get_max_num() size_t underflow on empty sysfs file Date: Tue, 21 Jul 2026 17:10:54 +0200 Message-ID: <20260721152615.958952490@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152552.646164743@linuxfoundation.org> References: <20260721152552.646164743@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arnaldo Carvalho de Melo [ Upstream commit 0a012113bb3a44482c163f16f4db03ccaa37a339 ] get_max_num() reads a sysfs file (cpu/possible, cpu/present, or node/possible) and scans backward from the end to find the last number. If the file is empty, filename__read_str() returns num == 0. The loop `while (--num)` decrements the size_t from 0 to SIZE_MAX, reading backward across the heap until a comma or hyphen is found or unmapped memory is hit. Add an early return for empty files before the backward scan. Fixes: 7780c25bae59fd04 ("perf tools: Allow ability to map cpus to nodes easily") Reported-by: sashiko-bot Reviewed-by: Ian Rogers Cc: Don Zickus Cc: Ian Rogers Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/util/cpumap.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c index b754e331bdfe8c..59173db168f16f 100644 --- a/tools/perf/util/cpumap.c +++ b/tools/perf/util/cpumap.c @@ -420,6 +420,12 @@ static int get_max_num(char *path, int *max) buf[num] = '\0'; + /* empty file — nothing to parse */ + if (num == 0) { + err = -1; + goto out; + } + /* start on the right, to find highest node num */ while (--num) { if ((buf[num] == ',') || (buf[num] == '-')) { -- 2.53.0