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 660452ED16D; Thu, 21 May 2026 01:11:35 +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=1779325896; cv=none; b=COUa4VAQBnEL4Ihmk9/IUrAHWy4ycUiaWx5VbpR1x5UWfVl78u2M23e71lutm2aXKgNkcqkTM2VT8AE3aX+MOzw1OAPqXbBHqdlgpA4O4sZKwX+aSrzfqArZo3c1pZi74rFV4X8hxczg7hRw8yf9X2AVwrO73ovUaGBWZio0zxg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779325896; c=relaxed/simple; bh=7ANnDTDRR8IsZ8u2lyRrnOOpJS5PWsMwqVg2FXvJpgE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=bsSMmc2Ffip4ANDflFdYKfz6Efz2dv7KOSIMk0V0ZZS/AUPA6GqHh3IrXhFnz3jVh886opwHsKy4+SdxTxXsWdqrOv99EkSfI/pjaJGlrW4bOJ7coijMN3QVmu7NmpvBHqZYvOoJLvQeqdAMM0J5SAkWBKpcn9cDdnLsYXjXIIM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jb4EwU8N; 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="Jb4EwU8N" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85A501F000E9; Thu, 21 May 2026 01:11:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779325895; bh=wfLF7hL4cp3FmDsLRc1sLgNOeR8HNr+cAMrD6g5a5Ag=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Jb4EwU8NW2ZS6sc4iXCUmXJPu7sM6lSraQmiaybi0w8DrAZmsqshF9H9x5Zd+QuEc 3qCcVN/HQrpYnX9u8i/UfV04gxcnFwWz2KvgQwXdisd/qpFG0PDU2j0Fxw5sQwF0p+ 0+dX+5IkuHo2MiWhyi76nP6Nd0dauiyN0aDiiejAnAE01g3Rsycl4NWOiiFdU2c9D8 FV23Og3XPeb+vWf9WrdSHXOtylKs3GOV2M6X/WbnEhxGmQ5shzMn53o1CFwhIPyWvo 7tlYGAInAfjilr1l7Ib2WSv/fk+YS9ClnAMRxt3hhXP9MpL5Q0sAN9FPbO088y0jk1 jG2JG1QQgXjrA== 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, Blake Jones , "Claude Opus 4.6 (1M context)" Subject: [PATCH 14/27] perf session: Add byte-swap and bounds check for PERF_RECORD_BPF_METADATA events Date: Wed, 20 May 2026 22:09:59 -0300 Message-ID: <20260521011027.622268-15-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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Arnaldo Carvalho de Melo PERF_RECORD_BPF_METADATA has no entry in perf_event__swap_ops[], so its nr_entries field is never byte-swapped when reading a cross-endian perf.data file. Downstream processing in perf_event__fprintf_bpf_metadata() loops over nr_entries, so a foreign-endian value causes out-of-bounds reads. Add a swap handler that byte-swaps nr_entries after validating that header.size is large enough. The entries[] array contains only char arrays (key/value strings), so no per-entry swap is needed — but ensure NUL-termination on the writable cross-endian path. Validate header.size, nr_entries, and string NUL-termination in the common event delivery path so that native-endian files with malicious values are also rejected. Snapshot nr_entries via READ_ONCE() before validation — the event is on a MAP_SHARED mmap that could theoretically change between the bounds check and the loop. Fixes: ab38e84ba9a8 ("perf record: collect BPF metadata from existing BPF programs") Reported-by: sashiko-bot@kernel.org # Running on a local machine Cc: Blake Jones 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/session.c | 85 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 84 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 5b089da2245457e7..928775f727c497cf 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -933,6 +933,45 @@ static int perf_event__time_conv_swap(union perf_event *event, return 0; } +static int perf_event__bpf_metadata_swap(union perf_event *event, + bool sample_id_all __maybe_unused) +{ + u64 i, nr, max_nr; + + /* Fixed header must fit before accessing nr_entries or prog_name */ + if (event->header.size < sizeof(event->bpf_metadata)) + return -1; + + event->bpf_metadata.nr_entries = bswap_64(event->bpf_metadata.nr_entries); + + /* + * Ensure NUL-termination on the cross-endian path where the + * mapping is writable (MAP_PRIVATE + PROT_WRITE). Fixing + * the string in place is preferred over rejecting because it + * preserves the event for downstream processing — only the + * last byte is lost. + * + * The native-endian path (MAP_SHARED + PROT_READ) cannot + * write, so it validates and skips unterminated events in + * perf_session__process_user_event() instead. The two + * strategies produce different outcomes for the same + * malformed input (fix vs skip), which is inherent in the + * writable-vs-read-only mapping model. + */ + event->bpf_metadata.prog_name[BPF_PROG_NAME_LEN - 1] = '\0'; + + nr = event->bpf_metadata.nr_entries; + max_nr = (event->header.size - sizeof(event->bpf_metadata)) / + sizeof(event->bpf_metadata.entries[0]); + if (nr > max_nr) + nr = max_nr; + + for (i = 0; i < nr; i++) { + event->bpf_metadata.entries[i].key[BPF_METADATA_KEY_LEN - 1] = '\0'; + event->bpf_metadata.entries[i].value[BPF_METADATA_VALUE_LEN - 1] = '\0'; + } + return 0; +} static int perf_event__schedstat_cpu_swap(union perf_event *event __maybe_unused, bool sample_id_all __maybe_unused) @@ -1032,6 +1071,7 @@ static perf_event__swap_op perf_event__swap_ops[] = { [PERF_RECORD_STAT_ROUND] = perf_event__stat_round_swap, [PERF_RECORD_EVENT_UPDATE] = perf_event__event_update_swap, [PERF_RECORD_TIME_CONV] = perf_event__time_conv_swap, + [PERF_RECORD_BPF_METADATA] = perf_event__bpf_metadata_swap, [PERF_RECORD_SCHEDSTAT_CPU] = perf_event__schedstat_cpu_swap, [PERF_RECORD_SCHEDSTAT_DOMAIN] = perf_event__schedstat_domain_swap, [PERF_RECORD_HEADER_MAX] = NULL, @@ -2172,9 +2212,52 @@ static s64 perf_session__process_user_event(struct perf_session *session, case PERF_RECORD_FINISHED_INIT: err = tool->finished_init(tool, session, event); break; - case PERF_RECORD_BPF_METADATA: + case PERF_RECORD_BPF_METADATA: { + u64 nr_entries, max_entries; + + if (event->header.size < sizeof(event->bpf_metadata)) { + pr_warning("WARNING: PERF_RECORD_BPF_METADATA: header.size (%u) too small, skipping\n", + event->header.size); + err = 0; + break; + } + + /* + * Native-endian files are mmap'd read-only — validate + * NUL-termination instead of writing. + */ + if (strnlen(event->bpf_metadata.prog_name, + BPF_PROG_NAME_LEN) == BPF_PROG_NAME_LEN) { + pr_warning("WARNING: PERF_RECORD_BPF_METADATA: prog_name not null-terminated, skipping\n"); + err = 0; + break; + } + + /* Snapshot — event is mmap'd and could change between reads */ + nr_entries = READ_ONCE(event->bpf_metadata.nr_entries); + max_entries = (event->header.size - sizeof(event->bpf_metadata)) / + sizeof(event->bpf_metadata.entries[0]); + if (nr_entries > max_entries) { + pr_warning("WARNING: PERF_RECORD_BPF_METADATA: nr_entries %" PRIu64 " exceeds max %" PRIu64 ", skipping\n", + nr_entries, max_entries); + err = 0; + break; + } + + for (u64 i = 0; i < nr_entries; i++) { + if (strnlen(event->bpf_metadata.entries[i].key, + BPF_METADATA_KEY_LEN) == BPF_METADATA_KEY_LEN || + strnlen(event->bpf_metadata.entries[i].value, + BPF_METADATA_VALUE_LEN) == BPF_METADATA_VALUE_LEN) { + pr_warning("WARNING: PERF_RECORD_BPF_METADATA: entry %" PRIu64 " key/value not null-terminated, skipping\n", i); + err = 0; + goto out; + } + } + err = tool->bpf_metadata(tool, session, event); break; + } case PERF_RECORD_SCHEDSTAT_CPU: err = tool->schedstat_cpu(tool, session, event); break; -- 2.54.0