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 4FB29217723; Thu, 30 Jul 2026 15:18:43 +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=1785424724; cv=none; b=hhkWwMdqNL6TlmFZKlLswt5ddv1S0jLTWU2vG8izkZNfdyrvvXwsCCqyxpYWx5SYwhT8g5UU+cId7UY8Tg5uxHppHOJcVLH7wYTSmyKj9DKNCiLyMY1p0Fp80uFo/1WR7WfBCPp3rHIn+1bFS422Lzjc2hCZVz1SrYSjg/bBcDI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785424724; c=relaxed/simple; bh=3Eu3F1dcaGYerjut/EJCT7T2iOf8gtzY1ZUNBqMsRcI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VS4FQT/c0B9hHAScBR+/peKX3gbacxlfIDCgV5dhIzYGG7415/B2OSKcYjzPvpXM0LNWz16F1r9qFVDXhpOE75d6v0YPtkChucUpLOWQZXBg7O3iCoCxhpA0f2uJb+olhtde0/5u8+mu+MP0e+OwY9Z0mzIF3iR0Ykzi2UfshRY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ks497fwj; 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="ks497fwj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA0AE1F000E9; Thu, 30 Jul 2026 15:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785424723; bh=JYJPWVBAq6GgT9K6vOONuYWbcgdl+gbMrTctVi24sio=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ks497fwjoxWCNecWyf4m/y/JihnMxIQxLIEhEwsRwMWD7fL/fM0D/IEonXAW/5LBD mUqZPsQzTeLoHxbQJjy8fu1MkAXrX2twmI00MRfawF8FByfoIjTdNNVEBclV1yw4NZ X0G/Uuj1TPm/cuvJ2bVG9KSIzUl45l31AD3y9Cp0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Masami Hiramatsu (Google)" , Steven Rostedt Subject: [PATCH 6.18 493/675] tracing: Fix union collision of module and refcnt for dynamic events Date: Thu, 30 Jul 2026 16:13:43 +0200 Message-ID: <20260730141455.600521322@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Masami Hiramatsu (Google) commit b4eb07bde606c2096b24252be589e735eff6d413 upstream. In 'struct trace_event_call', the 'module' pointer and the 'refcnt' atomic variable share the same memory space in a union. For dynamic events, the union member is 'refcnt', which acts as an active reference counter. When a dynamic event (such as kprobe, uprobe, fprobe, eprobe, or wprobe) has a non-zero reference count (e.g. due to active event triggers or perf attachments), its 'call->module' evaluates to a small non-zero integer instead of NULL. When filtering or setting events for a specific module (e.g., writing ':mod:' to 'set_event'), the code in '__ftrace_set_clr_event_nolock()' and 'update_event_fields()' reads 'call->module' directly without checking whether the event is dynamic. This causes the kernel to treat the small integer (refcnt) as a 'struct module' pointer, leading to a NULL/invalid pointer dereference (Oops) when dereferencing the module name. Fix this by ensuring that the 'TRACE_EVENT_FL_DYNAMIC' flag is checked before treating 'call->module' as a valid pointer in these code paths. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/178425670947.84440.11344393611899824907.stgit@devnote2 Fixes: 4c86bc531e60 ("tracing: Add :mod: command to enabled module events") Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -1333,7 +1333,9 @@ __ftrace_set_clr_event_nolock(struct tra call = file->event_call; /* If a module is specified, skip events that are not that module */ - if (module && (!call->module || strcmp(module_name(call->module), module))) + if (module && + ((call->flags & TRACE_EVENT_FL_DYNAMIC) || + !call->module || strcmp(module_name(call->module), module))) continue; name = trace_event_name(call);