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 6D17923395D for ; Thu, 10 Sep 2026 01:59:12 +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=1789005553; cv=none; b=hm7ImO6xWehJne0cjy+dUmSvK1W8t5AsnJ78Um+wl+xNjxHSYOz1rxR6x2V6Qvp15LDqv14hGYLpOqAGfEU0JV/OtMUaKEovyBtLs1inDFAO3+r8IMmmTWgWTxx/mznrGP0/oTx7cwS+3lCb7Pz96mpBUuld4vttCEx7js+BhaM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789005553; c=relaxed/simple; bh=WvLELWZFkDVU1PMTbPq4r3z1b7lftEJVMlUX0aDWtVQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ctSXgvTztPPirkNeqjKsU1T9prdhWynY+h1DICcYmA4G/xyuGCSdD1g+sfECO0r5/zwvv34UDbREVQHV6EdqGZAsA7atCVWRD7A+/C9Jgyml6L5gP0JMaKL9FykooNdhK9bWZ+S2w4ospj0Rj2cLMQvb/pkuemtJojx28VedagM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VExXimsv; 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="VExXimsv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C0F11F00893; Thu, 10 Sep 2026 01:59:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789005551; bh=20pXcDQVz3yD1LDxHFpKo70VyEHT2lTiErIe+ZEq9Pw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VExXimsvcrfY2LREr3m3rPvn4O7aDnTC2oZWBbLNEL4NwMzAa14GNGK3n4JPCPgA6 NZijnZTtOLKf/w4brx3N/rw/7nswLEjyZwjrtZxBU5JYZwiaOdwuKvpNgU4HwIRqMW +OqVS7PLS4jXxMwQldpiFmMQpzsKRUd8gYieNU2efgbWYpBS9D60h426egWcb1SEU3 usRn3Ii6z1q5RfZ0vJAu/11PW0oZxmqWhjt+mrhYDmBB60fbQEn6t3AyYyYhIFgCmJ 1KYF7LlTaibskYG3imwB37+4bPKqB+lqp2q71KxbRVa4U4Xxpj96IBCoMbyLqJb3Lh KIqWj4q3suEEA== 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 6.18.y] usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers() Date: Wed, 9 Sep 2026 21:59:09 -0400 Message-ID: <20260910015909.3948156-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090850-ethics-surfer-b50f@gregkh> References: <2026090850-ethics-surfer-b50f@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 6f275c3d11ac5..2a22a204c0e73 100644 --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -2748,6 +2748,9 @@ 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