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 B415714883F; Mon, 25 May 2026 01:06:10 +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=1779671171; cv=none; b=bNdQtV9GesAvEL3izB6ECThrXaNerWDMOn+hIRWX6xaXDQEEl7Ey8Yj/Tn8TKGHP/iJllDbArBiPEeUVMLzUJRTnIbGaT3Ta1KG/ly5YN98XXeoHu4aZpUl4zYGTfsT4WTfltXh7j4r5lFSdQktI1L+WOY7IlA3wcYieiIJIgpk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779671171; c=relaxed/simple; bh=EFl0ilw7DOSK6DwVd5+p0NyA5yFDMXfTnyy1U7dcmAo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Tpuup+lpPwmPtfSgy4A0l7GWn5mdYp1UCgGJTrMKXevE+2A+zVM7fIfYI6Qn8TJwCQ2VX/n/VmbkioYpzpEpJYeV7582AoKizIE7A1IYv4kz8deewvjas8c9EgSInaakrLa79a4FQ0DoqxAJNJdspdewaX3TkhVhQhxrDG4xOhI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M42c8lSe; 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="M42c8lSe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A1901F000E9; Mon, 25 May 2026 01:06:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779671170; bh=87T7wPlP1JWvoL8tVqclceY6ODGJmso4j6MMQOhWpYA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=M42c8lSehqXaJunsbuwO04NBbTHQg0LHGZa/SDJ/nO4deZnJ1cPHZz0z7BPTx9JqM ces69qOfruB3eMC3YcWDyS87+msvaIo55Z8KHMvaP0ymrByKV83sP0/8Sm8nKYLcbQ 6/WrbwS3RbkO+17oJe6L8gvT0fsMk43ZFPoUclimrq0SGF4Le8R2qcwd8YUEHjjCLW XoK8Vdg9zsD1W1zV1sDrMn4578MNnHPzUQ5Ukx3mlSongrIuSFZdRBavDwKNR35BC7 o4Eh6t0kvg0n61ihyEmLlNKOOnBCTFF9JQ0/s59Wr6ZPoAoGiX9xCDPoG+8dukRWDP pCtEA1cZyk3Zw== 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 02/29] perf session: Bounds-check one_mmap event pointer in peek_event Date: Sun, 24 May 2026 22:05:22 -0300 Message-ID: <20260525010550.1100375-3-acme@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260525010550.1100375-1-acme@kernel.org> References: <20260525010550.1100375-1-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 perf_session__peek_event() computes an event pointer directly from file_offset when one_mmap is active, without verifying that file_offset and the subsequent event->header.size fall within the mapped region. A corrupted perf.data file could cause out-of-bounds memory reads. Add one_mmap_size to the session struct and validate both the header and full event fit within the mmap before dereferencing. Reported-by: sashiko-bot@kernel.org # Running on a local machine Cc: Ian Rogers Cc: Namhyung Kim Assisted-by: Claude Opus 4.6 (1M context) Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/session.c | 29 ++++++++++++++++++++++++++--- tools/perf/util/session.h | 2 ++ 2 files changed, 28 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 0523fd243e02c09b..c4cd8ad6d810a74c 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1887,12 +1887,27 @@ int perf_session__peek_event(struct perf_session *session, off_t file_offset, *event_ptr = NULL; if (session->one_mmap && !session->header.needs_swap) { - event = file_offset - session->one_mmap_offset + - session->one_mmap_addr; + u64 offset_in_mmap; + + /* Validate offset with integer arithmetic to avoid pointer UB */ + if ((u64)file_offset < session->one_mmap_offset) + return -1; + + offset_in_mmap = (u64)file_offset - session->one_mmap_offset; + + /* Use subtraction to avoid addition overflow */ + if (offset_in_mmap >= session->one_mmap_size || + session->one_mmap_size - offset_in_mmap < sizeof(struct perf_event_header)) + return -1; + + event = session->one_mmap_addr + offset_in_mmap; - /* Every event must at least contain its own header */ if (event->header.size < sizeof(struct perf_event_header)) return -1; + + /* Ensure full event is within the mmap region */ + if (session->one_mmap_size - offset_in_mmap < event->header.size) + return -1; } else { if (perf_data__is_pipe(session->data)) return -1; @@ -2560,6 +2575,14 @@ reader__mmap(struct reader *rd, struct perf_session *session) if (session->one_mmap) { session->one_mmap_addr = buf; session->one_mmap_offset = rd->file_offset; + /* + * mmap_size was set to the full file extent (data_offset + + * data_size) but file_offset was shifted forward by + * page_offset for page alignment. Reduce by page_offset + * so the bounds check reflects the file-backed portion + * of the mapping — pages beyond the file cause SIGBUS. + */ + session->one_mmap_size = rd->mmap_size - page_offset; } return 0; diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h index f05f0d4a6c238dc8..d554e2a1a50ed304 100644 --- a/tools/perf/util/session.h +++ b/tools/perf/util/session.h @@ -71,6 +71,8 @@ struct perf_session { void *one_mmap_addr; /** @one_mmap_offset: File offset in perf.data file when mapped. */ u64 one_mmap_offset; + /** @one_mmap_size: Size of the single mmap in bytes. */ + u64 one_mmap_size; /** @ordered_events: Used to turn unordered events into ordered ones. */ struct ordered_events ordered_events; /** @data: Optional perf data file being read from. */ -- 2.54.0