From mboxrd@z Thu Jan 1 00:00:00 1970 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 679E439B947; Tue, 7 Apr 2026 08:55:09 +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=1775552109; cv=none; b=FbxD7aunUV6z07AX903DsU2Rdh5Y+MoQFyf1bgpp9BZmtX3e4v7XoONFqUgF5avAHw7dR2bgoc8WOP0f80Ri36eMo2o8PNFnEWjmFF0TWXwq5G5YSGHfgjYiTG5h6d2HPdlJ5yVcyuJV/gg7KqGOzRfx3QajUJjNxPWTEcRdBok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775552109; c=relaxed/simple; bh=GuKln7VYxHIG8btwCkuLT0R/K1AI0ImWbV7M1cCDesI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=at50NUVFiDn9/5kc8VUKDeRsQd3szT1p7AvNhQy8riMm2ygVbivOVw/UeybVnMOI0Im48vZHLMyQeosa78duthZgkEC+v0YYINqsKiqeOvhjEnfgTDcWO+IimcF5/ifnMjug7hqbbnDBcrEttQdPtGd10LLToW0eSET6b0yz0jw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dn9LnTiY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="dn9LnTiY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B857C2BCAF; Tue, 7 Apr 2026 08:55:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775552109; bh=GuKln7VYxHIG8btwCkuLT0R/K1AI0ImWbV7M1cCDesI=; h=From:To:Cc:Subject:Date:From; b=dn9LnTiYaVNnX+1p4Taeij1Wlx6Z3lZOxtArL/Sr8GAkRT7BAJ7k8xGzJngJ9juFP 1SP9kj0Vvo6E2RA+l82XFfhiS7DXVq+xXzhbA0/9GUiBUovI8dBxFX6gjMzm/Tszyw 3FHG2ciJAEXX7liWeFognn6E5zgPoFXktKyN4Gjg= From: Greg Kroah-Hartman To: linux-usb@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , stable Subject: [PATCH] usb: gadget: f_phonet: fix skb frags[] overflow in pn_rx_complete() Date: Tue, 7 Apr 2026 10:55:05 +0200 Message-ID: <2026040705-fruit-unloved-0701@gregkh> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1871; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=GuKln7VYxHIG8btwCkuLT0R/K1AI0ImWbV7M1cCDesI=; b=owGbwMvMwCRo6H6F97bub03G02pJDJlXjmWyspT0Htncnv8syvO9kozpq/Y9PW/n2wYt1Eit+ VKxd1dRRywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAExkzX2GBddU/hVUbTxcy262 QCMwuZ+JadINeYYFPSb+rMzstuJGL+I2HGDekB/OJy8KAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit A broken/bored/mean USB host can overflow the skb_shared_info->frags[] array on a Linux gadget exposing a Phonet function by sending an unbounded sequence of full-page OUT transfers. pn_rx_complete() finalizes the skb only when req->actual < req->length, where req->length is set to PAGE_SIZE by the gadget. If the host always sends exactly PAGE_SIZE bytes per transfer, fp->rx.skb will never be reset and each completion will add another fragment via skb_add_rx_frag(). Once nr_frags exceeds MAX_SKB_FRAGS (default 17), subsequent frag stores overwrite memory adjacent to the shinfo on the heap. Drop the skb and account a length error when the frag limit is reached, matching the fix applied in t7xx by commit f0813bcd2d9d ("net: wwan: t7xx: fix potential skb->frags overflow in RX path"). Fixes: 9732d5232335 ("Phonet: USB CDC Phonet function for gadget framework") Cc: stable Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_phonet.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/usb/gadget/function/f_phonet.c b/drivers/usb/gadget/function/f_phonet.c index 2c007790ead2..b1ee9a7c2e94 100644 --- a/drivers/usb/gadget/function/f_phonet.c +++ b/drivers/usb/gadget/function/f_phonet.c @@ -333,6 +333,15 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req) if (unlikely(!skb)) break; + if (unlikely(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)) { + /* Frame count from host exceeds frags[] capacity */ + dev_kfree_skb_any(skb); + if (fp->rx.skb == skb) + fp->rx.skb = NULL; + dev->stats.rx_length_errors++; + break; + } + if (skb->len == 0) { /* First fragment */ skb->protocol = htons(ETH_P_PHONET); skb_reset_mac_header(skb); -- 2.53.0