From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f42.google.com (mail-pj1-f42.google.com [209.85.216.42]) (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 4667038C2B8 for ; Fri, 22 May 2026 21:44:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779486267; cv=none; b=HGgK3j6119FrynRMVaSbGRnnFOp7FzTrvr2atNDH573mcKSVd5LY6uP7e0C0d6yeuVVCxhNQKeWQHiP9JwAow3m0VE4JWMo1Gk/ReXbnVpYvJRP1h62hV3ZT+RGnSmMOeCBBTaLk2JZGNadDggad3CLc00SZgYmpLiHtIFSTxTk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779486267; c=relaxed/simple; bh=p0D0SvAiOiNPeriwNwY4FWBYY3sdeg5voF6KW2g27tE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=YBq+fQgCY6VX2Rd0Fgeg5LNFsnmanKNChzzToV4dD163OStR0Q6gbIJQtslDGmKGMw90KE46xqHStxjcbKWL7b6ui2/gP6dSnZsgHbzmI91q6w6PHG4aPZ5zbygcwTEfyLpqgvOhJBF+8HDPixTQ/S6SUKdb7n+kheHlRw/48TM= 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=DwLpEvTL; arc=none smtp.client-ip=209.85.216.42 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="DwLpEvTL" Received: by mail-pj1-f42.google.com with SMTP id 98e67ed59e1d1-36a8ee1e28cso456228a91.0 for ; Fri, 22 May 2026 14:44:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779486265; x=1780091065; 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; bh=0a6+9FSkd4CAvkhrb+PFN6/wUARChFwi4N+F/39VGM0=; b=DwLpEvTLoqJjuEz0UqBazmZVWL6k9IHJGqD280ZZJlRAV7r7jZpNsz+h2DQa4c51Ul 2QJo1U3f609RCjKSCCbjTaj4sedh4m6hZ64yMXxa2AuqgZ16m6vtUneKlobACEPppVux S6fj9yfhzN07m5HunFd3E4wU78jBdxjQbPceHhL2WRLjhWGB709J4uNckMHWPThU3TdS pBYgWBqk69m33dydg3um6gZX54EOdy3KQqHjZBf/h6deEYd3JHV9cpV2H7STzgkdze+I 8O92bIvyJI5Y9YV9kqTASMeyMGcHQa1XSRwbMWVJOQ2VgyOKVQm173HtCI4ie9kUDtX0 VEdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779486265; x=1780091065; 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; bh=0a6+9FSkd4CAvkhrb+PFN6/wUARChFwi4N+F/39VGM0=; b=GD9dfMsy0eoy/BstYWCv0Ln1hB9Tt1j9L3Srh3gDiUhvYgcgEKLmDZbnkDikwMu4Z6 UD6QjV0pDXAH76auQg5OeDSqIARC8DEpF6xkU+Hpb0MbdCQNMm9tCSwESkSj+T4dr74a XwVh1Z1s0+7pvlH5T5SZU+i5vX11oRw4c2wuC/pdxUtziN92qru4NlTHC2uXcJoRfzNS Zw8Dq9sXfWoN5pcIzAyhVxaF/RBQAQwlxrV4IRonR/r7xrzHMPniM9ZT/c6hs9WXNQ/M Iuj6YdiEuvKY5ICZeIT/31nR4E6tJLhInvN1t+VgW/nVcIARbLqNU0eCmAWI70T0xUzA q5Qw== X-Gm-Message-State: AOJu0Ywcq3SQv4WX1DJQ+c6DJ5k24mavNqgSJEy0YX1eIfM/4XF8OpFR mAHmMBP5hoatjD8Hz64oYOiRXuTaUD2wSZz2iVjkPcWWxkfZ4rDmRZhzOOU4Wg== X-Gm-Gg: Acq92OGc9X8QN1lQB+IZQ/1USRdFn4s5JrHGa6zXl7RT5AmWKF+gitxoNK2I1cdPrSq 2i4lLCnflttBPoTAXzxKatRJz8PKl/v+F9wWrMY25lTiF2CY5wxanROuf/IB9eSnhUngXp+Nmzq +bvBmV32FHjjTUZu4XNFQpCaVVmR4xBL1Wlj5o5P2lvCPW6zbIjWJEcaEHaaIeKXyFbN+lazfNw vf7zv9nNNj6pk40r1yEqYSBGRCv7Riah3qvm7wJ5yOzdubSOauqOWm+4c5E8ODIpDalzdsY7ULa o8EqcwnEeiU4w6v07FHDwu+lTAP3vv/zOz1kG3UcuuJUIhbeXQwcKXvVVqzSK8gPAX5rI1JFV87 8WXzEhRwyai9llxvz1qeLOu05cifR6Y1nZAzZzQIlTfNVoQUb2898kBczffMG6rDF0EBuLDG2M4 lpSz+iT4Huq/If5HnJf0jyteuVrPiVhvP2t/df1jJKCVczkGRwHm+X7NPfLk7jMCsKIJDlrP2vw FOh7Bfjxxc5+92q1eTqymHOyNblKgh34LnTReWwtPE0Rg== X-Received: by 2002:a17:90b:3cd0:b0:369:a962:8cca with SMTP id 98e67ed59e1d1-36a6771bd1cmr5194148a91.11.1779486265449; Fri, 22 May 2026 14:44:25 -0700 (PDT) Received: from ryzen ([2601:644:8000:5b5d:7285:c2ff:fe45:8a32]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-36a721c858csm2812300a91.11.2026.05.22.14.44.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 May 2026 14:44:24 -0700 (PDT) From: Rosen Penev To: linux-trace-kernel@vger.kernel.org Cc: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Kees Cook , "Gustavo A. R. Silva" , linux-kernel@vger.kernel.org (open list:TRACING), linux-hardening@vger.kernel.org (open list:KERNEL HARDENING (not covered by other areas):Keyword:\b__counted_by(_le|_be|_ptr)?\b) Subject: [PATCH] trace: turn hist_elt_data field_var_str into a flexible array Date: Fri, 22 May 2026 14:44:07 -0700 Message-ID: <20260522214407.18120-1-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 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 The field_var_str array was allocated separately via kcalloc() with its length already known at elt_data allocation time. Convert it to a flexible array member and fold the two allocations into a single kzalloc_flex(), reordering hist_trigger_elt_data_alloc() so n_str is computed and bounds-checked before the struct allocation. hist_elt_data is only reached through tracing_map_elt::private_data (a void *), never embedded, so adding a FAM imposes no tail-position constraint on any enclosing struct. Added __counted_by for extra runtime analysis. Assisted-by: Claude:Opus-4.7 Signed-off-by: Rosen Penev --- kernel/trace/trace_events_hist.c | 31 +++++++++++-------------------- 1 file changed, 11 insertions(+), 20 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index a64c76f6905f..1fd0899c606c 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -683,8 +683,8 @@ struct track_data { struct hist_elt_data { char *comm; u64 *var_ref_vals; - char **field_var_str; int n_field_var_str; + char *field_var_str[] __counted_by(n_field_var_str); }; struct snapshot_context { @@ -1629,8 +1629,6 @@ static void hist_elt_data_free(struct hist_elt_data *elt_data) for (i = 0; i < elt_data->n_field_var_str; i++) kfree(elt_data->field_var_str[i]); - kfree(elt_data->field_var_str); - kfree(elt_data->comm); kfree(elt_data); } @@ -1650,10 +1648,19 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt) struct hist_field *hist_field; unsigned int i, n_str; - elt_data = kzalloc_obj(*elt_data); + BUILD_BUG_ON(STR_VAR_LEN_MAX & (sizeof(u64) - 1)); + + n_str = hist_data->n_field_var_str + hist_data->n_save_var_str + + hist_data->n_var_str; + if (n_str > SYNTH_FIELDS_MAX) + return -EINVAL; + + elt_data = kzalloc_flex(*elt_data, field_var_str, n_str); if (!elt_data) return -ENOMEM; + elt_data->n_field_var_str = n_str; + for_each_hist_field(i, hist_data) { hist_field = hist_data->fields[i]; @@ -1667,24 +1674,8 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt) } } - n_str = hist_data->n_field_var_str + hist_data->n_save_var_str + - hist_data->n_var_str; - if (n_str > SYNTH_FIELDS_MAX) { - hist_elt_data_free(elt_data); - return -EINVAL; - } - - BUILD_BUG_ON(STR_VAR_LEN_MAX & (sizeof(u64) - 1)); - size = STR_VAR_LEN_MAX; - elt_data->field_var_str = kcalloc(n_str, sizeof(char *), GFP_KERNEL); - if (!elt_data->field_var_str) { - hist_elt_data_free(elt_data); - return -EINVAL; - } - elt_data->n_field_var_str = n_str; - for (i = 0; i < n_str; i++) { elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL); if (!elt_data->field_var_str[i]) { -- 2.54.0