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 5AF723BE175; Sat, 30 May 2026 18:19:36 +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=1780165177; cv=none; b=Dtts41c1b5rahuqRnZLLVSN1suoU+WScDLxKvFrbVmlL3pfqBckvRfixQEJGPl9YekJCAiQDFwb7WXpWhGMD7v3JrB5CxyXaE0g3zUEgHbtOc6QjEHAZAYnD9mQYhGq/cDMXyy0Yk/VINHfigYAoUTL0nPJkCvh4YzamMLWkTCY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780165177; c=relaxed/simple; bh=71h4j+XDyCKEDDY3AE8C1QRdhZaLH/zb0Uwv0Dz2I3A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ghcNoiQBS8tWCf6twCLweW1doJRA+8pOu/f3FPozXbL7Q8QK9p2+byE3yaqe7EkgcVkejuH4DpeCt9h5sZVhtWQiDijr2LxtJsH2bG3Isko2Z5/VM83xP6n7XWuxdU1/viwwvz0J6q2ZgxX9vq77RTxNVUzFYQhnEcNejEtVlnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jiXEn2r5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jiXEn2r5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F6C51F00893; Sat, 30 May 2026 18:19:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780165176; bh=AUKyJ/I0FoAKhjTGf+JKTyoMMrzyDmY59Vhr2urRjec=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=jiXEn2r51h75oMWU4Qx3ZtOwxmbn2dzVmjUpGjJqBWMYZFDf1Wfnu1CLifln3+Oxu 7jqLy1dKo7iMocWluZSZ5t3R4JB7ua0VdtNKzYoVogjXQhjJRFG8NTrkw5Si7MWfNP +87YD0nQkgCEGGivBMJbA2jiP8KLlMwsF8IzjIbs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Carlier , Steven Rostedt , Sasha Levin Subject: [PATCH 5.15 771/776] tracing: Avoid NULL return from hist_field_name() on truncation Date: Sat, 30 May 2026 18:08:05 +0200 Message-ID: <20260530160259.638833313@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160240.228940103@linuxfoundation.org> References: <20260530160240.228940103@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Carlier [ Upstream commit 576ec047d20b368b43c4d5db98c4f2e0f3c101ec ] hist_field_name() returns "" everywhere except the fully-qualified VAR_REF/EXPR case, where snprintf() truncation returns NULL early and bypasses the bottom NULL->"" guard. Callers don't expect NULL: strcat(expr, hist_field_name(field, 0)) at trace_events_hist.c:1758 and the strcmp() in the sort-key match loop at :4804 both deref it. system and event_name are bounded by MAX_EVENT_NAME_LEN, but the field name on a VAR_REF is kstrdup'd from a histogram variable name parsed out of the trigger string and has no length cap, so a long enough var name in a fully qualified reference can reach the truncation path. Keep the length check but leave field_name as "" on overflow. Link: https://patch.msgid.link/20260508195747.25492-1-devnexen@gmail.com Fixes: 5ec1d1e97de1 ("tracing: Rebuild full_name on each hist_field_name() call") Signed-off-by: David Carlier Signed-off-by: Steven Rostedt Signed-off-by: Sasha Levin --- kernel/trace/trace_events_hist.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 03473d1e5f8bf..5ecc78916431d 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1146,10 +1146,8 @@ static const char *hist_field_name(struct hist_field *field, len = snprintf(full_name, sizeof(full_name), "%s.%s.%s", field->system, field->event_name, field->name); - if (len >= sizeof(full_name)) - return NULL; - - field_name = full_name; + if (len < sizeof(full_name)) + field_name = full_name; } else field_name = field->name; } else if (field->flags & HIST_FIELD_FL_TIMESTAMP) -- 2.53.0