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 39260306768; Thu, 21 May 2026 01:12:13 +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=1779325934; cv=none; b=GIMsjjkFUc5bKf5LAV/TmbD92CQDiFMqRx8Jav6yn1TS7SN8DKuJLQyHFEdg+dL5JOr32g4eLhMDvtZpCQiw8ejakMbbxOPVvnkqN+yVxQiI7GrY6ATM1FNguzpEbs+WdB+dOYFUhqpstPaHEI5B+/5APEHh3vwd5yl//TvL34I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779325934; c=relaxed/simple; bh=/DCnT6jDug1BmvSNjveuZ+WerLEOJejT2NJhiI8D0/o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=a4lud1pXhRDbcYD87FwwtsvdKiKbLPriIvivHOha/G5JzSHOZ3FMKE+gqtqjJlMS/Z7S/kVjnvf39WvsACBZIi7imQO6PWgYytM/tvz91M4X+a6nTkg07slK4kBealbEc8cvV+9bqENzo27rx7kRt8xsoxKLdiURA2esczQNOuE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HFmfVL30; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HFmfVL30" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DEB871F000E9; Thu, 21 May 2026 01:12:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779325933; bh=XbcPDwGAi64vr2qIRi1JYjbatAK0bs/CUotXphvheJ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HFmfVL30lA2uiSX4wss2NV7Xnq+JJ4VaoVPA8uCezLTM4bcx7Djk9Qx1hUfUAtwgk s1fTIRioij1duA/QBTosFgN9DF2ff1mpoX7UK3Xjp4d8j1norm2X4H74ivBQX9/9M+ cUILB+4OW6Q/CI/7vhRrKJgq9yaFOdgkC8ns0kqHFzYBtGSd7xnuayjba7BUobP9gK chlFASSA2Sm85gKi/7vXD+hsb1kWh+jA60KBY1gB+fVWy5fhU0L4uUSAxxXR+pVgqO a89oe8WYXVU0XcSbTRGLxyJENM0mTLhlzuN+FksXJ3l4+GT/gr/vPtF82kQRTWW04c JQXKIzFf/HtEw== From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Ingo Molnar , Thomas Gleixner , James Clark , Jiri Olsa , Ian Rogers , Adrian Hunter , 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 24/27] perf session: Check for decompression buffer size overflow Date: Wed, 20 May 2026 22:10:09 -0300 Message-ID: <20260521011027.622268-25-acme@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260521011027.622268-1-acme@kernel.org> References: <20260521011027.622268-1-acme@kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@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 bounds individual values, but two additions can still overflow: 1. decomp_len += decomp_last_rem: on 32-bit, adding a u64 to size_t silently truncates, producing a corrupted decomp_len that would bypass the subsequent overflow check and result in an undersized buffer allocation. 2. sizeof(struct decomp) + decomp_len: even with the cap, the final addition could overflow on systems with small size_t. Add explicit overflow checks before each addition as defense-in-depth. Reported-by: sashiko-bot@kernel.org # Running on a local machine Cc: Ian Rogers Cc: Jiri Olsa 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 18641919473a859f..25c9b378aa163664 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