From nobody Fri Dec 19 14:37:01 2025 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 EB01E32A3E5 for ; Wed, 5 Nov 2025 14:24:51 +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=1762352694; cv=none; b=BiKxkB96MHC4pCvLOx/C/9eRZ+zCbuzQ69i5anu7qWKmExLXNkw+8Nt+WWmZexovCF7xXWhImWBLLfvHwoAwLN3QHm40kwECDv09saVZX5Xqseui7o8CsWadnt7d1lEnWJlvigmMY1t4/bFiaPfrTpKCKU/1HuVKp8CWmNWbebc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762352694; c=relaxed/simple; bh=RP9/Pa7uZjadz5VS6K6Zhwhg0tGtMF7soZM7ynErla8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZcG4iW5YqscM2qX4LzuqeT7p+woJNYu4R0+dcyGKtXI75A3GQxh3WYNGhjaCitmrtv3ss5Vnjj25LXTY0wLOGyJIV9DeAP0bWVXpWwDUkalV/Wy5JukatraHCYg44M6LnWzhcssnu5S3p7z0dC5i+T29cjVlzd6nJxFPdc+iKgE= 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=mVAGaCwc; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=mVAGaCwc; 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="mVAGaCwc"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="mVAGaCwc" Received: from pathway.suse.cz (unknown [10.100.201.202]) by smtp-out2.suse.de (Postfix) with ESMTP id 2044B1F78C; Wed, 5 Nov 2025 14:24:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1762352688; 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=tlN6ktgHSU/f8xH1FiBJde/pat8uEOiShatc5EeBNHs=; b=mVAGaCwcbsJpndDfUnlSuIcgdhIek4f/E7+V6Yc6PvrDAcnQ5eqSHbT2gjbR4qNcL7iJJd sExiflclqJoQRuQ96t6mQscJ0k2ySEwMCNw1Mv1lolANBTUTHKCXaTOnNgwYgcVtboqVD2 iEgRYj0JjHme7pep4TteiPW4O/6wr7A= Authentication-Results: smtp-out2.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1762352688; 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=tlN6ktgHSU/f8xH1FiBJde/pat8uEOiShatc5EeBNHs=; b=mVAGaCwcbsJpndDfUnlSuIcgdhIek4f/E7+V6Yc6PvrDAcnQ5eqSHbT2gjbR4qNcL7iJJd sExiflclqJoQRuQ96t6mQscJ0k2ySEwMCNw1Mv1lolANBTUTHKCXaTOnNgwYgcVtboqVD2 iEgRYj0JjHme7pep4TteiPW4O/6wr7A= From: Petr Mladek To: Petr Pavlu , Steven Rostedt , Alexei Starovoitov , Andrew Morton , Kees Cook Cc: 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 6/6] kallsyms: Prevent module removal when printing module name and buildid Date: Wed, 5 Nov 2025 15:23:18 +0100 Message-ID: <20251105142319.1139183-7-pmladek@suse.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251105142319.1139183-1-pmladek@suse.com> References: <20251105142319.1139183-1-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-Spam-Level: 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)[17]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TAGGED_RCPT(0.00)[]; FREEMAIL_CC(0.00)[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)[suse.com:email,suse.com:mid]; R_RATELIMIT(0.00)[to_ip_from(RLh88t7rzwwfj8wh1imqozhtme)]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; FREEMAIL_ENVRCPT(0.00)[gmail.com] X-Spam-Flag: NO X-Spam-Score: -5.30 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(). Signed-off-by: Petr Mladek Reviewed-by: Aaron Tomlin --- kernel/kallsyms.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index ff7017337535..1fda06b6638c 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -468,6 +468,9 @@ 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