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 94E4F36194D for ; Thu, 10 Sep 2026 02:14:11 +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=1789006452; cv=none; b=HbhTj688qOhZ6C3X+SXAbqg+mDYkz5mSiJOiY1ipFQNotPevYJJ4p+H8ZfWdo6TVO5Rk5snrje8aelXBwUW7hO8Bk5BttDqQHNL91Y3zT5+JTUK2BXveVEk9k+fvYURXh4m6MyuwNEVklqKRV8ewfVRYBIVP+ghU1RWDlju915g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789006452; c=relaxed/simple; bh=tKcx+5Vsjjnr9AK3kzWngurtrLTwcaOuoWgt3CggJVQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=JdzFKyCf0Nrp/1mFdHeKqtZnRkTpVHWZiBhiQe5FM9MSS+gR8u8qWRBzxhUK9I+5JNwbUpKKDPKVS15V6LY3aLjpULYBZJJ6PYu2MsN/4iV8KqYzh4hChTLE8WziT7znu+dMArY1lQ/nbc9zAgTZfHWBW9Zrc+UthhC1F8F7Tl4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=deECWw0f; 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="deECWw0f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B51311F000FF; Thu, 10 Sep 2026 02:14:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789006451; bh=OxLclSyoHj+B4aaUI9/kR+YJN5OlLsArhd55/S98xW8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=deECWw0fQ8jCkjNbbFqpRpbSv2obLZwb1lf/FeFx3/WfIKqnanSB/rn/Kc0pItFr9 VqO1sP5lo6lRFkYCfkF/3NRKZuAy9ToY+0xIf1baBV7E09Eh4wFYQhHWmgEtNIZFKU AwFk+afhqDMP7tDG434aOW9Jh3CuzKdKQawDHr5o9OJ6aIzMdGU93MFL6nSGcBazEP LTrCmMoh+ZHnEdBltJ1Nihyloulpz4eNEAVg/Mh5DS66uD8Ed2KEl2Iw4CnLTw19Ms 6SKsj2s4iEQsewJpD6cYSDUlzJv1qAb0s+A46PXc7mBgt2A5PTdnipkT17BXKvF407 CflGg3Md/fTtg== 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 6.6.y] usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers() Date: Wed, 9 Sep 2026 22:14:09 -0400 Message-ID: <20260910021409.3997045-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090851-diameter-thermal-3fb2@gregkh> References: <2026090851-diameter-thermal-3fb2@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 e01d57a5327c6..f149560f8a9b7 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