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 863C72F8BC3; Sun, 24 May 2026 03:29:28 +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=1779593370; cv=none; b=rR/0jJB6v4EvpiL1M+5L7QVLOyj2I0hzQB+IZp8dLYTUNJBdpMk0txKxaukCDgzL4YSLCk9qH1J2Es8lja1tHO/jUpas5GhoMWAHjcjq/VZXLdXfvqY/RBPA4u/f2DEscrPz3Hfxhq0f3stk1RwVbtjEDQuo8AdG1fFq0798NGg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779593370; c=relaxed/simple; bh=2tspnYnFV2/mcTNat8MjyF0yJMZPMqCkwJiD0xzu5Pc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=rKQXEH7M6akdk/sy3octxnnezXUYTkDt7cea5Q0u+2+BTtcBzVmVH6t3z5rLllXOCv3IsIn7c0JZK1GzKF03nxpGmLVjfRY7xVk6VvjTTWjasbmZ/+3aI4ZdBBXBThcES73vSZJRh4YGNNW5wACCx91Ax/AejVC3ksjQWICIBCk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EXsT9IuG; 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="EXsT9IuG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25C811F00A3A; Sun, 24 May 2026 03:29:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779593368; bh=mVc8jbO9aj9r6TWlD3OrE7dSxeoBoQfzzEhSx+Srlww=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EXsT9IuGkUEgDYzMQUE2+si3zuLsWziSAwCg9YhSwkLyWUTBLkvEMNjPWgCVG3Yzs is46wD+91E8W4Dk80r4jLe/juImbrKFsqQU2sIpgg3yVAeteHqjgXB9zB49qtNSPAb 8pw78FFmMCadg3lXqzH0IXi541umiGaYbqWyaQn9tJ9/i2WMOrqUSpdJYIoHdkqbaM TmMwJVZU74G0WDujITRkuumMubJX2DKR0m4eVRC6CUBRZSzaFwnjJnGihfp9R1t4f3 tYBjgfpaBdBr7x+mLKbSm6JhlsPLs/1Yh/eyp2WMfwSw+Wrq4XoWSYtdXPJWha9cdn mEn948iBvtvEQ== 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, Wang Nan , "Claude Opus 4.6 (1M context)" Subject: [PATCH 21/29] perf header: Sanity check HEADER_EVENT_DESC attr.size before swap Date: Sun, 24 May 2026 00:26:55 -0300 Message-ID: <20260524032709.1080771-22-acme@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260524032709.1080771-1-acme@kernel.org> References: <20260524032709.1080771-1-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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Arnaldo Carvalho de Melo read_event_desc() reads nre (event count), sz (attr size), and nr (IDs per event) from the file and uses them to control allocations and loops without validating them against the section size. A crafted perf.data could trigger large allocations or many loop iterations before __do_read() eventually rejects the reads. Add bounds checks in read_event_desc(): - Reject sz smaller than PERF_ATTR_SIZE_VER0. - Require at least one event (nre > 0). - Check that nre events fit in the remaining section, using the minimum per-event footprint of sz + sizeof(u32). - Pre-swap attr->size to native byte order, then reject values below PERF_ATTR_SIZE_VER0 or above sz before calling perf_event__attr_swap() to prevent heap out-of-bounds access. - Handle ABI0 (attr.size == 0): substitute PERF_ATTR_SIZE_VER0, and on native-endian files write the value back so free_event_desc() does not treat the zero as its end-of-array sentinel (it iterates while attr.size != 0). The swap path skips the write-back — perf_event__attr_swap() has its own ABI0 fallback that sets VER0 after swapping. - Check that nr IDs fit in the remaining section before allocating. Fixes: b30b61729246 ("perf tools: Fix a problem when opening old perf.data with different byte order") Reported-by: sashiko-bot@kernel.org # Running on a local machine Cc: Ian Rogers Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Assisted-by: Claude Opus 4.6 (1M context) Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/header.c | 54 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 90417a478c8db2e1..37d7c9849e0e9199 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -2173,9 +2173,28 @@ static struct evsel *read_event_desc(struct feat_fd *ff) if (do_read_u32(ff, &nre)) goto error; + /* Size of each of the nre attributes. */ if (do_read_u32(ff, &sz)) goto error; + /* + * Require at least one event with an attr no smaller than the + * first published struct, and reject sz values where + * sz + sizeof(u32) would overflow size_t (possible on 32-bit) + * or nre == UINT32_MAX where nre + 1 wraps to 0 in the calloc. + * + * The minimum section footprint per event is sz bytes for the + * attr plus a u32 for the id count, check that nre events fit. + */ + if (!nre || sz < PERF_ATTR_SIZE_VER0 || + sz > ff->size || (size_t)sz > SIZE_MAX - sizeof(u32) || + nre == UINT32_MAX || + nre > (ff->size - ff->offset) / (sz + sizeof(u32))) { + pr_err("Invalid HEADER_EVENT_DESC: nre=%u sz=%u (min %d)\n", + nre, sz, PERF_ATTR_SIZE_VER0); + goto error; + } + /* buffer to hold on file attr struct */ buf = malloc(sz); if (!buf) @@ -2191,6 +2210,9 @@ static struct evsel *read_event_desc(struct feat_fd *ff) msz = sz; for (i = 0, evsel = events; i < nre; evsel++, i++) { + struct perf_event_attr *attr = buf; + u32 attr_size; + evsel->core.idx = i; /* @@ -2200,6 +2222,32 @@ static struct evsel *read_event_desc(struct feat_fd *ff) if (__do_read(ff, buf, sz)) goto error; + /* Reject before attr_swap to prevent OOB via bswap_safe() */ + attr_size = ff->ph->needs_swap ? bswap_32(attr->size) : attr->size; + /* ABI0: size == 0 means the producer didn't set it */ + if (!attr_size) { + attr_size = PERF_ATTR_SIZE_VER0; + /* + * Write back so free_event_desc() doesn't + * treat this event as the end-of-array sentinel + * (it iterates while attr.size != 0). + * + * Only for native — the swap path must NOT + * write native-endian VER0 here because + * perf_event__attr_swap() would re-swap it + * to 0x40000000, defeating bswap_safe() bounds. + * perf_event__attr_swap() has its own ABI0 + * fallback that sets VER0 after swapping. + */ + if (!ff->ph->needs_swap) + attr->size = attr_size; + } + if (attr_size < PERF_ATTR_SIZE_VER0 || attr_size > sz) { + pr_err("Event %d attr.size (%u) invalid (min: %d, max: %u)\n", + i, attr_size, PERF_ATTR_SIZE_VER0, sz); + goto error; + } + if (ff->ph->needs_swap) perf_event__attr_swap(buf); @@ -2221,6 +2269,12 @@ static struct evsel *read_event_desc(struct feat_fd *ff) if (!nr) continue; + /* Prevent oversized allocation from crafted nr */ + if (nr > (ff->size - ff->offset) / sizeof(*id)) { + pr_err("Event %d: id count %u exceeds remaining section\n", i, nr); + goto error; + } + id = calloc(nr, sizeof(*id)); if (!id) goto error; -- 2.54.0