From nobody Wed Feb 11 01:27:21 2026 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (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 B53B233032C for ; Wed, 12 Nov 2025 14:21:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762957311; cv=none; b=AcwF2GAD/tOS6OeIy+9Lz8DuiJIcbNaCwJcRiK64OKKzMPXo6Aj9g9n72oSezxvjJIczsMsb+8N0wS0kjk70Tvz1xc3rsJT0+fKIHSQZoT29EDir1qNCV1rIeL62CycDTkNrG8fSrg7c3NOB2TeXY/J9nOjRlIyidg2dgP4U9lU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762957311; c=relaxed/simple; bh=DErfb1yw71TjXX1m2fEvBmVvRDvk5oiZa5z6kIuTRKA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hHAtmmA55FYibab3nLmqaKKm3F/6iMLy9M/Wsre5kF/Ny+Z2PE8G/DLMwngYD9Amz/dsbTdbSjbslnOXJmVRcZ/rPpaiAf+4MHl4YOoi28R2szVgKTUnISfLhTFxriKufWUrOreJkfVYelNdg5XTs5xMTYZd0amuF0bKo2bamaM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=Fwm4E1Ut; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=ek/OUc1L; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Fwm4E1Ut"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="ek/OUc1L" Received: from pathway.suse.cz (unknown [10.100.208.146]) by smtp-out2.suse.de (Postfix) with ESMTP id E2A561F807; Wed, 12 Nov 2025 14:21:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1762957308; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=97I/A52s9/abeslkIlgFB5lHhNmcwVQr9GlDloyKxh0=; b=Fwm4E1Utf5nc5WoVAJu8cPbGqYJ663EAiMUr/dgD+haLJtJDSIcHPLVCstP0e3WjSOyVfL 39XTW3sBJh9rrJpBYxUGdJ/vEbrIGUF1xbftuqISTH9XzIGuFllUp4K1p6cRVP8z78xg9G Lx9r2Hkyv/iU1gSYpAnO1AI1iHmlcxs= Authentication-Results: smtp-out2.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1762957307; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=97I/A52s9/abeslkIlgFB5lHhNmcwVQr9GlDloyKxh0=; b=ek/OUc1L8yezFuEAGDJzTqJ+8mCV7yLr5PfXO+bwcp0xVnqW4RJjJ6UsOksg2or/65hKKb GF94DTt31+xP9WOXSka14/oe6F8IQ9cgWvXrVP3QKtCUe6Ax86F4RO8qb3QVsNLhyD24xm 8u8FIpZ5z2VqK5lcE6vsJa0kgttZ0Go= From: Petr Mladek To: Petr Pavlu , Steven Rostedt , Alexei Starovoitov , Andrew Morton , Kees Cook Cc: Aaron Tomlin , Daniel Borkmann , John Fastabend , Masami Hiramatsu , Mark Rutland , Luis Chamberlain , Daniel Gomez , Sami Tolvanen , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-modules@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Petr Mladek Subject: [PATCH v2 7/7] kallsyms: Prevent module removal when printing module name and buildid Date: Wed, 12 Nov 2025 15:20:03 +0100 Message-ID: <20251112142003.182062-8-pmladek@suse.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251112142003.182062-1-pmladek@suse.com> References: <20251112142003.182062-1-pmladek@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Spamd-Result: default: False [-5.30 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCPT_COUNT_TWELVE(0.00)[18]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TAGGED_RCPT(0.00)[]; FREEMAIL_CC(0.00)[atomlin.com,iogearbox.net,gmail.com,kernel.org,arm.com,google.com,vger.kernel.org,suse.com]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_ZERO(0.00)[0]; DBL_BLOCKED_OPENRESOLVER(0.00)[atomlin.com:email,pathway.suse.cz:helo]; R_RATELIMIT(0.00)[to_ip_from(RLw9bydq1j5bti46rxed9sjz7y)]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; FREEMAIL_ENVRCPT(0.00)[gmail.com] X-Spam-Flag: NO X-Spam-Score: -5.30 X-Spam-Level: Content-Type: text/plain; charset="utf-8" kallsyms_lookup_buildid() copies the symbol name into the given buffer so that it can be safely read anytime later. But it just copies pointers to mod->name and mod->build_id which might get reused after the related struct module gets removed. The lifetime of struct module is synchronized using RCU. Take the rcu read lock for the entire __sprint_symbol(). Reviewed-by: Aaron Tomlin Signed-off-by: Petr Mladek --- kernel/kallsyms.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 5bc1646f8639..202d39f5493a 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -471,6 +471,9 @@ static int __sprint_symbol(char *buffer, unsigned long = address, unsigned long offset, size; int len; =20 + /* Prevent module removal until modname and modbuildid are printed */ + guard(rcu)(); + address +=3D symbol_offset; len =3D kallsyms_lookup_buildid(address, &size, &offset, &modname, &build= id, buffer); --=20 2.51.1