From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C0BA146D557 for ; Tue, 21 Jul 2026 17:34:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784655249; cv=none; b=NVqFkHyKrVQjFGHPGnnMSIktHjxvvIfWDiqOiX8OL+yU9oNCoLm38uq/yZ1n1tw1slZg6kQBUnP4ZOphlqnrorUD+P1xTyAUD686UoY55q2FTwdsRUrp2TPEWHHTOJp4k8Xf93EisB0lUMkTjtKAGm8K94pyY3GU+c4+Em6hNZE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784655249; c=relaxed/simple; bh=5HHYV2YtuskvpVXWLLiEwNUcmcEMrY8dXvLciuEgNo4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=rQNno9FaWjVNvYe1uwJG2+Btb7RkCoc47oXA92neoY6t2lAKsYe3aY7FQev3gxucTKKmcymXnUQrebflESypRyFiFqk5D35BllaR3h9kdhZe4vTht9be0EHcqa8RzjxrH2cJxVyhzQugU7FWpb7efWjmc1rJd08t6MHl5zF2x/Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=QrcWUTkH; arc=none smtp.client-ip=209.85.215.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QrcWUTkH" Received: by mail-pg1-f199.google.com with SMTP id 41be03b00d2f7-c9c26587e67so5743246a12.0 for ; Tue, 21 Jul 2026 10:34:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1784655247; x=1785260047; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=dVysXzCxvN0YWO4pl9MoMoRFZ8JrR13DJYNHpKFDQUI=; b=QrcWUTkHE114E7/73aCuWVO78Dg69vNN63FnEcdFqdB6zpCF09Hc/37JmCPGXONDr3 9YI/tnODDZEZyqRjsrGFAA5hSLHVXedOuHx5tdXgkLC1dMLpxIuCg3CfTs7CAwHJWSpy J+Nte1rb53/ht8XVL1kaZclpPm9GfOPq9QBwS6hjUF6BrEns6G/Yum1d6N8jrk3+fsY2 oK+vx3e4FR/SMoyCnAmq1iehtvZ91wgvbcFlVlCY397o3FXI+tnZbcxQ7ynsUPXDMO7E z8505BqumwTEIfg0ZPXsNjbWQaJ9EYVJWOc+HQHks33QOblarJTDi9DSOi++d+DjUD2F lYtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784655247; x=1785260047; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=dVysXzCxvN0YWO4pl9MoMoRFZ8JrR13DJYNHpKFDQUI=; b=nJoC6W3BQXp/eiK1iwErhjKszqyvo890lY8f/21CL7/gPL5wg1VYPH/mO9MvGrWHIY lqldQQ84IRwSh+KZxPtoN4yI+P9CQLl4DelY0Ry4Cmz/ZHH3xX2ZvHZ6S4tBuCdPt/HB QK8XO+MoQPHueQcgI+vnHD4cH0xTk9rhIwYinMXAzSgvkT8+fpRF3gVsU3c4cUOPdZeM gMyT1hwxT30+4ai1r/NiHwFK1YVR7E8Xu2E+RV65nRuNXcvnzNkl75L8iB7saNn6j6Di em+VSkIsIKPckLKSPUtlCe0JTWGR5RaDT/bpxf/syyXh1vi1xTp/7Z49ls/7C12kURlW RhbA== X-Forwarded-Encrypted: i=1; AHgh+Rrvm03FFm443yhHFQUto2b/JUeBSy6QcKduvtAspJ2O1fS0lq9un7VTwBxYLh1/A+zvmP/Lqt3Xeqflapf/sIfI@vger.kernel.org X-Gm-Message-State: AOJu0YyDGMY81FNkmWwRvw62ihAnqn4syiAfoWqm4lQKNcpXuudJ52/w yKGKyBpLBVWelk4Ugn/pTjs+Nve3IU9OAcRjf7/v6nAMao742tb6HAL6gJpCt66ILK8UnoW5xpO Mqv+EbAr1Dw== X-Received: from dldyq2-n2.prod.google.com ([2002:a05:701b:4542:20b0:139:ce3e:27b3]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:4d05:b0:3bd:1cfc:1b9b with SMTP id adf61e73a8af0-3c4292c1e37mr586336637.10.1784655246881; Tue, 21 Jul 2026 10:34:06 -0700 (PDT) Date: Tue, 21 Jul 2026 10:33:46 -0700 In-Reply-To: <20260721173347.9163-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260720225200.3810501-1-irogers@google.com> <20260721173347.9163-1-irogers@google.com> X-Mailer: git-send-email 2.55.0.229.g6434b31f56-goog Message-ID: <20260721173347.9163-4-irogers@google.com> Subject: [PATCH v3 3/4] perf synthetic-events: Fix bounds, stale state, and misc flags in kernel module synthesis From: Ian Rogers To: irogers@google.com, acme@kernel.org, namhyung@kernel.org Cc: adrian.hunter@intel.com, james.clark@linaro.org, jolsa@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, ravi.bangoria@amd.com, swapnil.sapkal@amd.com Content-Type: text/plain; charset="UTF-8" Fix potential buffer overruns in perf_event__synthesize_modules_maps_cb() by safely clamping long DSO names to the mmap/mmap2 filename boundaries. Explicitly assign and clear the misc flags and union padding across all iterations to prevent stale Build-ID state from leaking between module synthesis events. Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Ian Rogers --- tools/perf/util/synthetic-events.c | 70 +++++++++++++++++++++--------- 1 file changed, 50 insertions(+), 20 deletions(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 9a2b4d561e9e..068323b9510d 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -754,6 +754,7 @@ struct perf_event__synthesize_modules_maps_cb_args { perf_event__handler_t process; struct machine *machine; union perf_event *event; + u16 misc; }; static int perf_event__synthesize_modules_maps_cb(struct map *map, void *data) @@ -761,49 +762,78 @@ static int perf_event__synthesize_modules_maps_cb(struct map *map, void *data) struct perf_event__synthesize_modules_maps_cb_args *args = data; union perf_event *event = args->event; struct dso *dso; - size_t size; + size_t size, aligned_size; + int rc = 0; if (!__map__is_kmodule(map)) return 0; dso = map__dso(map); if (!symbol_conf.no_buildid_mmap2) { - size = PERF_ALIGN(dso__long_name_len(dso) + 1, sizeof(u64)); + const char *long_name = dso__long_name(dso); + + size = strlen(long_name); + if (size >= sizeof(event->mmap2.filename)) + size = sizeof(event->mmap2.filename) - 1; + + strlcpy(event->mmap2.filename, long_name, + sizeof(event->mmap2.filename)); + + aligned_size = PERF_ALIGN(size + 1, sizeof(u64)); event->mmap2.header.type = PERF_RECORD_MMAP2; - event->mmap2.header.size = (sizeof(event->mmap2) - - (sizeof(event->mmap2.filename) - size)); - memset(event->mmap2.filename + size, 0, args->machine->id_hdr_size); + event->mmap2.header.misc = args->misc; + event->mmap2.header.size = + offsetof(struct perf_record_mmap2, filename) + + aligned_size; + + /* Zero the padding and ID header trailer safely! */ + memset(event->mmap2.filename + size, 0, + (aligned_size - size) + args->machine->id_hdr_size); + event->mmap2.header.size += args->machine->id_hdr_size; event->mmap2.start = map__start(map); event->mmap2.len = map__size(map); event->mmap2.pid = args->machine->pid; - memcpy(event->mmap2.filename, dso__long_name(dso), dso__long_name_len(dso) + 1); - - /* Clear stale build ID from previous module iteration */ + /* Clear stale build ID and entire union from previous module iteration */ event->mmap2.header.misc &= ~PERF_RECORD_MISC_MMAP_BUILD_ID; memset(event->mmap2.build_id, 0, sizeof(event->mmap2.build_id)); event->mmap2.build_id_size = 0; + event->mmap2.__reserved_1 = 0; + event->mmap2.__reserved_2 = 0; perf_record_mmap2__read_build_id(&event->mmap2, args->machine, false); } else { - size = PERF_ALIGN(dso__long_name_len(dso) + 1, sizeof(u64)); + const char *long_name = dso__long_name(dso); + + size = strlen(long_name); + if (size >= sizeof(event->mmap.filename)) + size = sizeof(event->mmap.filename) - 1; + + strlcpy(event->mmap.filename, long_name, + sizeof(event->mmap.filename)); + + aligned_size = PERF_ALIGN(size + 1, sizeof(u64)); event->mmap.header.type = PERF_RECORD_MMAP; - event->mmap.header.size = (sizeof(event->mmap) - - (sizeof(event->mmap.filename) - size)); - memset(event->mmap.filename + size, 0, args->machine->id_hdr_size); + event->mmap.header.misc = args->misc; + event->mmap.header.size = + offsetof(struct perf_record_mmap, filename) + + aligned_size; + + /* Zero the padding and ID header trailer safely! */ + memset(event->mmap.filename + size, 0, + (aligned_size - size) + args->machine->id_hdr_size); + event->mmap.header.size += args->machine->id_hdr_size; event->mmap.start = map__start(map); event->mmap.len = map__size(map); event->mmap.pid = args->machine->pid; - - memcpy(event->mmap.filename, dso__long_name(dso), dso__long_name_len(dso) + 1); } if (perf_tool__process_synth_event(args->tool, event, args->machine, args->process) != 0) - return -1; + rc = -1; - return 0; + return rc; } int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, @@ -828,13 +858,13 @@ int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__han } /* - * kernel uses 0 for user space maps, see kernel/perf_event.c - * __perf_event_mmap + * Just like the kernel, see perf_misc_flags() in + * kernel/events/core.c */ if (machine__is_host(machine)) - args.event->header.misc = PERF_RECORD_MISC_KERNEL; + args.misc = PERF_RECORD_MISC_KERNEL; else - args.event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL; + args.misc = PERF_RECORD_MISC_GUEST_KERNEL; rc = maps__for_each_map(maps, perf_event__synthesize_modules_maps_cb, &args); -- 2.55.0.229.g6434b31f56-goog