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 71E7436606A for ; Thu, 10 Sep 2026 02:22:36 +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=1789006957; cv=none; b=iGiGNIdfZpOvpCyBh0jldwHje0JJeQFIzvNfb8vLMwLD2hXvNd//r9o32EjbD6ma7Jx5s5/Z2QedE8xYKoV6O1iyjCkz0NSzFbUdoF04onkV/hPbKP+eXSKMvOxJQRrrKRucR/OGFO+CE/ak3Gn9sUDqEj+fTMpUoDgVfK9v4EY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789006957; c=relaxed/simple; bh=d+A7SaPPza8HZmJlTmXut0Nn4itaUG4ds3SsnM5TVEk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=cItJdAV9AzuRJtb3uT67iFdw2y8JT/+CNze13zZXpMekm8dmz6q3lMi32cdHyJayzz8TSL90gdo06e9dtUyktU89CRrA46TY59MRqadH8Vsa5my0K+Mvx2HJCt6n6dNw64kHOmGXM6fuulS8glBo889eV+h0pS3qJZPvyh8OHT0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G0tc2QNw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G0tc2QNw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D2931F000FF; Thu, 10 Sep 2026 02:22:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789006956; bh=wT/Hwi4YzH4wSodyjl5FYcIO5LfNAq2Gigiur7IPblo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=G0tc2QNw/2ecJUxdONwQEgGWpvBjZNMzROuE/1eT0dxp691do5G3ZKIfKN+OfMol+ csgTX3gbIJ+DMWZ10SqvqI1UIJldLj9IgQspm9ewrY1xJmzuv9zKwlTbp9aCIkzYJ9 Pc0ItuY6LwcvkU1JcIbe8cuV+6dkkR13FHJB4MSDRooozHJRSGQCLx9rk1a7640EO7 QHPcsk+MH+mZ5s8kRqBDD1FAQQ4wB7YYOGMj+lyNEHNONm/qJRdD1qzYFSfbzuZq1O K0cjs14TdtbqsD5ZNyNh0MdZMci3j9PIujz9BMj+NLFp0YkPj+dSLaAWTj/G9Gm4gK wClQogWQ2w3oA== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeffin Philip , syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com, stable , Alan Stern , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 5.15.y] usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers() Date: Wed, 9 Sep 2026 22:22:33 -0400 Message-ID: <20260910022233.4023433-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090851-disprove-ointment-dbd3@gregkh> References: <2026090851-disprove-ointment-dbd3@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jeffin Philip [ Upstream commit 2c0f5ca48674a5b5f9fa4a9c3325aa48053af0bc ] Previously fsg_num_buffers_validate() was removed as it was not necessary due to Kconfig setting the limits for n from 2 to 256 with default as 2. However, setting the page content in such a way that kstrtou8() reflects n value as either 0 or 1 bypasses these restrictions leading to a null pointer dereference if n is 0. Fix this by adding a check for n < 2 and returning -EINVAL if n is either 0 or 1 consistent with Kconfig logic. Reported-by: syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=791be35f1fbcc85d06d7 Fixes: fe5a6c48fd95 ("usb: gadget: storage: get rid of fsg_num_buffers_validate()") Cc: stable Signed-off-by: Jeffin Philip Acked-by: Alan Stern Link: https://patch.msgid.link/20260818035904.10324-1-jeffinphilip14@gmail.com Signed-off-by: Greg Kroah-Hartman [ adjusted context to retain the branch’s existing kcalloc() call instead of kzalloc_objs(). ] Signed-off-by: Sasha Levin --- drivers/usb/gadget/function/f_mass_storage.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c index f602eee451a35..76c0246714c9f 100644 --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -2592,6 +2592,9 @@ int fsg_common_set_num_buffers(struct fsg_common *common, unsigned int n) struct fsg_buffhd *bh, *buffhds; int i; + if (n < 2) + return -EINVAL; + buffhds = kcalloc(n, sizeof(*buffhds), GFP_KERNEL); if (!buffhds) return -ENOMEM; -- 2.53.0