From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f43.google.com (mail-pj1-f43.google.com [209.85.216.43]) (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 7E6572F0661 for ; Sun, 13 Sep 2026 20:31:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789331498; cv=none; b=UPjOHiUdOPgANHyQ4COHQdgLZq/hwA7velbS8FVUpgzmRdhq7LMfzZZCkihMI1rALBnxmHAyJUCrGxYG09PRFYpHcm7cjpkO75VtmB1Cqz/iJq7F5GTKnAyl3OJ4Rtqwf02U3JDVOF0zbKD9nEqUMLKFV+7KGtWsnpKhqMyq2mM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789331498; c=relaxed/simple; bh=yDn7QK/ba+3RLVHPMTBb8o7wMnI8vkCF4rNDGAc/jgc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=DNF1CajSCuG6LWlojRt+wV/gMECKK6ez/5GcJTlBbuiiekBibGzuD2v+Y2cqXUL3xe1Rqv8IF+YJUU82xtvXHu2Ivx4tgg4YoWOlyZgYVBgl3bSCYIwFKHi32fTVXlVKEj5ocVKIeDDSW+aCvi/NvPF8epW1RwnklOMTLx07R2A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=dg1MKUOP; arc=none smtp.client-ip=209.85.216.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="dg1MKUOP" Received: by mail-pj1-f43.google.com with SMTP id 98e67ed59e1d1-3990fe066ebso2099397a91.1 for ; Sun, 13 Sep 2026 13:31:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1789331497; x=1789936297; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=6LszAmsFoGsrZf03eXVx9RZkN93lj99VFwvSyBMy7+c=; b=dg1MKUOPm/Jf/HEBRknTTsIHbkbEzm8H3MerCbHX9gG88ZTZ4d5Bp0y1/SAyGnUYzJ sdnIHukSRgxQSoqHcRLpN7dV9+AmKFIaXk/D3dEPVTDWfuQTFHQqK+XhPvDA4zv41SAL yMqlr44N7s99jWBrv7+5Gv7t8qz8BaebtCutfZex5BDWpT60EbibbfpYW3+hqsAxY6SQ iJmxvqBcTEsGicSREc1L5mL1yIm+FJYviyod36tyrSy3Yiuy+Tt0dU3QirCFQAhrEaFL 8tqCC1f/gCQmUEzRBV/ZC7wd6C3HgZJMwda0PmRtD4uDMXp/kLbDEchaE+sRaU0WFE/o 4VFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1789331497; x=1789936297; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=6LszAmsFoGsrZf03eXVx9RZkN93lj99VFwvSyBMy7+c=; b=k9mJuv+GMG4ilADWiqCp3yu2kjyC0Sf2H7z6AV4VopcPfGP2n/T38P4BCx/pjk8sb7 z676yYNK6fc2oyLgeqLojVaCwzm7dDx4AOsSh/cCKZw5yJPMhyVXAKumlRxIFxtB77Oi G0cxaHPmbZGRL/YZCvrBf9b3Rp7qjlFz9fjBlJr1fptUtfL7wSsbQ1uaE5X6HUcVf1Us 7RJ86yS2MIeaazDu+kv627Cl+b6tuFXUe1vV1clqQSbLQqgSqxJgqf7qFe2/yc/alfTd OiQHavhT6h+UqNd0NTcN2NY7wgWhsR1OdyVRGcoYksArse4OvwYDMP77XFOaRCxg4oaE Re2Q== X-Forwarded-Encrypted: i=1; AKwUvByX2jHhmuO9ow+4zx+xejHIBCADFGOJ0iQXg186ARRAiNqXj5nC7Z9idOalkypFRMg1TcKTPhHt1a3mXvv5cmKrJe4=@vger.kernel.org X-Gm-Message-State: AFuF++kPDZ30V/4nVG2oy7H0DCiST2w75mE8bgKnGyD9NNccQx3fopTk dNmwjBA0sw7ZglVg9SoNygEH209V+U4Po3xxSDBAsvhrjyPEZoeCpM4= X-Gm-Gg: AYBFou20MsN9D0AHkUzdQ10Dxp4zaFDfa20GjoTXZs6SiG3J/yLg72lXDJ61AhJPi4u gwz0/ykjlf8Zpp78sa50rYvPIonZuVCAumusFyuZEimYHhS3J6SpppDRcCYIDOTDMeeVOteDTKm 1tbsQHbyVOg1OUWRkdumCE30iBMX7d0X78OlKrK4KGxo1j0drep4o7t7yNstM4pXbYEC5ky9Zfm L9w8LaSChC2WgjXm+BsS1sAQYhn0BIbs52+TSvh7xzeFSow9foMqOVKiV8CyHSMewGMJCHgtBFx wp1Z35IFibFP9SUC0kZPImfm6X5fSpHpcmbN3nNBysP6E9lwASo9kbMrVGxO22v9g13Z1U5ZIXp tC6xLCKm5l3+l/47fcJI/MjsXlTXuLqhYJYfCIYhzwZSj4HePilg1f+5hHimQ9Ud4k/LREf+43V IX2glhr+rCrzaeXhKyLF3NrAv9Is8VJrKBsuxs/OIk7P2ZKkPuUbXWazA6XGDMTtwbYooAvMx+U A2pjRwMsSmr0oP5uir7o0tkx2yKU/5Yf8kE X-Received: by 2002:a17:90b:51c8:b0:38e:5b59:c2ff with SMTP id 98e67ed59e1d1-39d9bbc802bmr24389520a91.3.1789331496799; Sun, 13 Sep 2026 13:31:36 -0700 (PDT) Received: from ydg-Zenbook-14-UM3406GA ([2001:2d8:7f00:8c85:b91:ff81:c860:362e]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39d94744dfdsm17530220a91.0.2026.09.13.13.31.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 13 Sep 2026 13:31:36 -0700 (PDT) From: Donggeun Yoo To: Steven Rostedt , Masami Hiramatsu Cc: Mathieu Desnoyers , Tom Zanussi , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Donggeun Yoo Subject: [PATCH v2 0/2] tracing: Fix NULL dereference when copying keys for a field variable Date: Mon, 14 Sep 2026 05:31:27 +0900 Message-ID: <20260913203129.941270-1-donggeunyoo.kernel@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A hist trigger with an onmatch() action copies the key list of the compatible histogram it finds on the matched event. Reading each key's name straight out of key_field->field->name faults on any pseudo-field key. 2/2 renders the key with expr_field_str() instead; 1/2 teaches that renderer to emit a bucket count, which 2/2 needs before it can use it. Link: https://lore.kernel.org/linux-trace-kernel/20260912094722.3271147-1-donggeunyoo.kernel@gmail.com/ Changes since v1: - Split the single patch in two. - Dropped the third change, which gated the ".stacktrace" arm of get_hist_field_flags() on hist_field->field. It fixes nothing: hist_field_print() excludes FL_STACKTRACE before it ever calls get_hist_field_flags(), and parse_field() takes the "stacktrace" modifier on any field. Measured with and without it: identical generated command on all nine key kinds below. - 1/2 is not separable from 2/2. .buckets is refused on a value, so no expression can reach expr_field_str() with a bucketed field, and 2/2 alone turns a working .buckets key into a refused one. In this order no bisection point regresses. The command create_field_var_hist() generates, for each kind of key the copied histogram can carry: WK key unpatched patched pid keys=pid keys=pid pid.log2 keys=pid keys=pid.log2 pid.buckets=10 keys=pid keys=pid.buckets=10 common_cpu oops keys=common_cpu common_comm oops keys=common_comm common_timestamp oops keys=common_timestamp common_timestamp.usecs oops keys=common_timestamp.usecs common_stacktrace oops keys=common_stacktrace.stacktrace hitcount oops keys=hitcount x86_64 under QEMU, CONFIG_KASAN=y, 4 CPUs, base 2f0c1cf72f46. A compatible histogram on sched_waking keyed on WK, an onmatch() target on sched_switch keyed on SK, my_synth($wakeup_lat,prio) forcing a field variable. Donggeun Yoo (2): tracing: Add the bucket size to expr_field_str() tracing: Fix NULL dereference when copying keys for a field variable kernel/trace/trace_events_hist.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) -- 2.53.0