From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A6CA1285CB4; Sun, 10 May 2026 03:36:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778384209; cv=none; b=rbgV/Wl+rrlh7YPnHTtfVSd/ENHmDGSQSYwstav8l7SRwdTrl8elBSt4S1y/FoYREYKIh5kyIDaspgXEsA9kXkFAp0a96NNldS5kNWHxHD1IFN7+4WAqqH2X93oNshdwop5P/H2Zy7uRLsAGGwowmzrmH+WFT6ZXQvNfxhpW34I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778384209; c=relaxed/simple; bh=BmgSgr1QoQ1SSGA4sPYjM5DUkysC6eOki83batJ4ME4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OYllW7TTRPyz+F5IoJrOxdnflrSDlsPg1gKh3FYD2OtDr83lrQwDSgaHbzOhWJVpSuOoqKgcdUS2D3rXg7I3K1L6jNVLrGtPonmTUXVvZTnOCzLE/ph2otbKjKbYVTjhLdkw78JUKQ0A6PAYx+P+qnJrwgfixejAyDxBu0RgDV4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L4uFi53a; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="L4uFi53a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D68BC2BCF6; Sun, 10 May 2026 03:36:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778384209; bh=BmgSgr1QoQ1SSGA4sPYjM5DUkysC6eOki83batJ4ME4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L4uFi53aRs03Kf/xtylfUfK4MT3TTrgpgjcspSSQxewWJSlhm2jMqKn9LSD+YgH8v ds7FQZjXjW3Rg/TMasp6uq8/sbty8NhkwTL84iCQMy0oJ6wWYZxFjDRNaDt+rhi1z5 /lC5Ynp+c1SD09/hEJZ7h2mv/P+KvWrGpEBogV9iY0MjAyXQ516Sjv+8AfycL3NWog t2K68QPW+mP3mVpa6EiZw60STbpOon/IcpOIIwtLr+D5eZAadwd2EZTyqi7+vsaM7b A+g0DRfhBT3Ss/EFST74TFsRxp35lRqzpUlUigPtgVn5tUxqsDlmyq8UV8Q1hoUHYR H2jdHc61tMnNA== From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Ingo Molnar , Thomas Gleixner , James Clark , Jiri Olsa , Ian Rogers , Adrian Hunter , Kan Liang , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , sashiko-bot@kernel.org, "Claude Opus 4.6 (1M context)" Subject: [PATCH 24/28] perf session: Check for decompression buffer size overflow Date: Sun, 10 May 2026 00:34:15 -0300 Message-ID: <20260510033424.255812-25-acme@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260510033424.255812-1-acme@kernel.org> References: <20260510033424.255812-1-acme@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Arnaldo Carvalho de Melo On 32-bit systems, sizeof(struct decomp) + decomp_len can wrap size_t when comp_mmap_len is large. The preceding patch caps comp_mmap_len at ~2 GB, which prevents decomp_len from exceeding SIZE_MAX after adding decomp_last_rem, but the subsequent addition of sizeof(struct decomp) could still theoretically overflow on systems with very small size_t, resulting in a tiny mmap allocation while zstd receives the original large decomp_len as the destination size. Add an explicit overflow check before computing mmap_len as defense-in-depth. Reported-by: sashiko-bot@kernel.org # Running on a local machine Cc: Jiri Olsa Cc: Ian Rogers Cc: Namhyung Kim Assisted-by: Claude Opus 4.6 (1M context) Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/tool.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/tools/perf/util/tool.c b/tools/perf/util/tool.c index 96fa6d6c55cdca1e..bb13d526ce4c3382 100644 --- a/tools/perf/util/tool.c +++ b/tools/perf/util/tool.c @@ -34,9 +34,22 @@ static int perf_session__process_compressed_event(const struct perf_tool *tool _ if (decomp_last->head > decomp_last->size) return -1; decomp_last_rem = decomp_last->size - decomp_last->head; + /* + * Check before adding: on 32-bit, size_t += u64 + * silently truncates, bypassing the overflow check + * below and producing an undersized buffer. + */ + if (decomp_last_rem > SIZE_MAX - decomp_len - sizeof(struct decomp)) { + pr_err("Decompression buffer size overflow\n"); + return -1; + } decomp_len += decomp_last_rem; } + if (decomp_len > SIZE_MAX - sizeof(struct decomp)) { + pr_err("Decompression buffer size overflow\n"); + return -1; + } mmap_len = sizeof(struct decomp) + decomp_len; decomp = mmap(NULL, mmap_len, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); -- 2.54.0