From nobody Sat Apr 4 00:21:40 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C2B712DF6F6 for ; Sat, 21 Mar 2026 14:41:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774104076; cv=none; b=Pj8q2A5meB5IMGGYUnnl67/4yr8RPnJv28Fr5/sGmhSyYWJZMslyNtt8HkmizcAX25ELn3jTjFiVdouqEkdhlGwOtGN76yqGDH+zPvSkXVIJdRDTM/yjOSASz8LdforvNFuiAgiBwrrPh8OkI/4uWjupAM3ndNzZpnTDHgx0Das= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774104076; c=relaxed/simple; bh=wKEz/F0djnuL058+wAjhhI1S8SSWtf4awfvW6bpkkbw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lYPCBnkYj4sMmDcfWwJzLcYn5sIaAQ9n1T++tkHe8pj2hoMMdbO8gZNZSPU0qRoUYO+BalP7R179VdegjHJnOrPW3hdLKFk9i3G6EkLDyze7fBeXzYzks1r0e7msSLmEMFbt/AbOgZLGEzYZfO0yRy+XpectKm+3nF05Ek4OXno= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bDyQE5Q2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bDyQE5Q2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1C2BC19421; Sat, 21 Mar 2026 14:41:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774104076; bh=wKEz/F0djnuL058+wAjhhI1S8SSWtf4awfvW6bpkkbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bDyQE5Q2VaNZnLdJaKTJCH6olnjw/SpjHJnM224hu9vvYeBXScAA7F23OPXjp1UEj eAa3x7BfoJbYsxJyC5amKtg60IdSMTy+D7oDciOroIqeVuvpj0Rh5q2A4PCAjO8KtQ +vq5cx3Js2HZObuMHbjptC+f4HVGQe4txcRcofMXMjKY0WD2qz6251wYj7rLNNOKUX +h+mbKCsjsadXbSgVpxKLj8iV7WF9w64apW1WiLnnQMl0SQAZ6EZLDCR16vstxArW6 983BBbG7Wy3aRflsBriZBBCImZa0fHhEP1UvP0nPGRLRjBhFR3Jh0vjPygW51sUeqC k3Jlr2ADtLQWQ== From: "Masami Hiramatsu (Google)" To: Petr Mladek , Steven Rostedt , Andy Shevchenko Cc: Rasmus Villemoes , Sergey Senozhatsky , Andrew Morton , David Laight , linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] lib/vsprintf: Fix to check field_width and precision Date: Sat, 21 Mar 2026 23:41:12 +0900 Message-ID: <177410407207.38798.2345647618225402693.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <177410406326.38798.16853803119128725972.stgit@devnote2> References: <177410406326.38798.16853803119128725972.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Check the field_width and presition correctly. Previously it depends on the bitfield conversion from int to check out-of-range error. However, commit 938df695e98d ("vsprintf: associate the format state with the format pointer") changed those fields to int. We need to check the out-of-range correctly without bitfield conversion. Fixes: 938df695e98d ("vsprintf: associate the format state with the format = pointer") Reported-by: David Laight Closes: https://lore.kernel.org/all/20260318151250.40fef0ab@pumpkin/ Signed-off-by: Masami Hiramatsu (Google) --- Changes in v3: - Check and update width and precision before assigning to spec. Changes in v2: - Fix to use logical split. --- lib/vsprintf.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 800b8ac49f53..ce9cbe071ab2 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2802,19 +2802,21 @@ struct fmt format_decode(struct fmt fmt, struct pri= ntf_spec *spec) static void set_field_width(struct printf_spec *spec, int width) { - spec->field_width =3D width; - if (WARN_ONCE(spec->field_width !=3D width, "field width %d too large", w= idth)) { - spec->field_width =3D clamp(width, -FIELD_WIDTH_MAX, FIELD_WIDTH_MAX); + if (WARN_ONCE(width > FIELD_WIDTH_MAX || width < -FIELD_WIDTH_MAX, + "field width %d too large", width)) { + width =3D clamp(width, -FIELD_WIDTH_MAX, FIELD_WIDTH_MAX); } + spec->field_width =3D width; } =20 static void set_precision(struct printf_spec *spec, int prec) { - spec->precision =3D prec; - if (WARN_ONCE(spec->precision !=3D prec, "precision %d too large", prec))= { - spec->precision =3D clamp(prec, 0, PRECISION_MAX); + if (WARN_ONCE(prec > PRECISION_MAX || prec < 0, + "precision %d too large", prec)) { + prec =3D clamp(prec, 0, PRECISION_MAX); } + spec->precision =3D prec; } =20 /* From nobody Sat Apr 4 00:21:40 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4637437646E for ; Sat, 21 Mar 2026 14:41:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774104086; cv=none; b=Dt846FGgfH8xCChDrCu57rSt8EkEBPhrRIm3kWYiEebRfRa228fO9985ASAx3DaqmuMAD5vsOyFvYaNr9Ra5dvFEQkKrm8xvMgXAWzFy6A7Fj9F2ie18SD/uD3mxygOs6v6qKXDptnki3LgXYL/nRyyPAeB+DcqcXX9wY1v2bjc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774104086; c=relaxed/simple; bh=OfB6qlo3ZG2QI+bH/Jm76OK3zNlpfuaiATcPoFwS5OE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=AJYNHPYDO1KBO5MKYiGIabRdpn7pfuGc9Ggy9HVCC1RJyzbdqMgulgOFL8k/PNlpvi09ZAc/rAItrp2AhoxpwflYTv1lxLf+MahVT2XUsVjy4u8bDuUKtYST7f1hZOopgbs4uIN5wQTe74eyit2oGX6Ovne2TJPXNzlxnMN0iyM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZMWqrYcw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZMWqrYcw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83DBFC19421; Sat, 21 Mar 2026 14:41:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774104085; bh=OfB6qlo3ZG2QI+bH/Jm76OK3zNlpfuaiATcPoFwS5OE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZMWqrYcws6BxsqQxsr/wsHs7quh2bcu1qyHPK169sz+mZdsrEtcXCkzelNa+wpwL5 Yt1JnSBB+xNi5D/Mo+SRHxpeaJ1QyXiYNViveIrN3eZssdx6C0EdRAVOQdM85jxFXQ GwRCJNvnOqteSpKyjgwe/oFaYOufW7Kb4DQzCwycskl4HQZwpRKnO0NU0RYv3M4xsW WcpYooa1lTwY0rCCg0Xy35vrXkREob/LlaiNIC7FOwrTA2ODjFStNl1BtnwBPdZEf5 f3+Ln1gRZvruTqQZukFGy8ChXj/VKDMzqvm48eLy04FOn8Sets3EZECH+oI82EVh1V CbKNmGyyzRioA== From: "Masami Hiramatsu (Google)" To: Petr Mladek , Steven Rostedt , Andy Shevchenko Cc: Rasmus Villemoes , Sergey Senozhatsky , Andrew Morton , David Laight , linux-kernel@vger.kernel.org Subject: [PATCH v3 2/2] lib/vsprintf: Limit the returning size to INT_MAX Date: Sat, 21 Mar 2026 23:41:21 +0900 Message-ID: <177410408170.38798.4383977339045208453.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <177410406326.38798.16853803119128725972.stgit@devnote2> References: <177410406326.38798.16853803119128725972.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) The return value of vsnprintf() can overflow INT_MAX and return a minus value. In the @size is checked input overflow, but it does not check the output, which is expected required size. This should never happen but it should be checked and limited. Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Petr Mladek --- Changes in v3: - Use local variable for better readability. --- lib/vsprintf.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index ce9cbe071ab2..396021a50355 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2866,6 +2866,7 @@ static unsigned long long convert_num_spec(unsigned i= nt val, int size, struct pr int vsnprintf(char *buf, size_t size, const char *fmt_str, va_list args) { char *str, *end; + size_t ret_size; struct printf_spec spec =3D {0}; struct fmt fmt =3D { .str =3D fmt_str, @@ -2985,8 +2986,12 @@ int vsnprintf(char *buf, size_t size, const char *fm= t_str, va_list args) } =20 /* the trailing null byte doesn't count towards the total */ - return str-buf; + ret_size =3D str - buf; =20 + /* Make sure the return value is within the positive integer range */ + if (WARN_ON_ONCE(ret_size > INT_MAX)) + ret_size =3D INT_MAX; + return ret_size; } EXPORT_SYMBOL(vsnprintf);