From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f47.google.com (mail-pj1-f47.google.com [209.85.216.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C13811397 for ; Sat, 29 Aug 2026 01:19:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787966354; cv=none; b=eB8WdJ4G+DkLgBTeoHoW/6iAowVZIsQYbgntbpuqiFpsSqGnxtEo26TcUbwwSqIz8TKN4L7zV+hGbMfeinZmc4EL3E/JZ7cCKU97z+vu/oJ0+V+1gh/ZmJiKXOFIHWdf3tGNElA8xshn5EbhOPIVgUvYBuC8MaycBq/ullj3FxE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787966354; c=relaxed/simple; bh=HscXdFpNsRlkFpSvaVpcYt8mqsjP9QoFN8kKOJceJZ8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ezdJ7eZAULrz+x8xMGnQJJmx0nOC9tTD0coZEHJqzg6EiteHn6trmbN6aoyuD+tJWdk7beRWZ+Hix9/MFHE5D7FFxEaY1xktmTPzhdOqmvhJWi07sAdKew7FBxoOcjRbXZ399oBgy4EWEQ7C3PbWm/1/tyAEd4ruTNv13DH/jgU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=F1Xd6sBx; arc=none smtp.client-ip=209.85.216.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="F1Xd6sBx" Received: by mail-pj1-f47.google.com with SMTP id 98e67ed59e1d1-38d489b6b71so1888211a91.0 for ; Fri, 28 Aug 2026 18:19:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1787966352; x=1788571152; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=fZg8mAdLVuaPOBvQhtWMylhZ2H86Gw6DTQC1M2Z4EuA=; b=F1Xd6sBx3vrV87skcElJnPIPJBt/P28uvFHzZ2w41E7w0S529D5Gs9VAEPFd7o6UHW xPpArbTSNB7K8m6BsR7K4p1Ug2IfLHhHRXYG1HDqIVX9p/l/C6+yD4K2B8qDXZgakWTI kN6L3dLJgBBbiHH7XnDOvd7Vjxj7QVfOkg+b1KVwOCQIeWVwiZmx7250WtldhvGJZ3ce oxDMArggVi90A/vz7yIaCfOuXBRLJqEFYAZMtzp1b+P6LYJtGyrQBrzFDmWFr822T8VP RvBfqWxqnwT5wXCGvu4T5khNiuaqzTrZHWNkfNLRo1oEN0J5nIW1jly1RmL8fceuWsKo H1tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787966352; x=1788571152; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=fZg8mAdLVuaPOBvQhtWMylhZ2H86Gw6DTQC1M2Z4EuA=; b=eJQ4W8NSO7WjgTj5/RttYJucIYQWt6ekHCysFM36Ds6glpEmG9SY/KU8Pxa8oApjBt x9A2zKX2RvaoWoub1bHzYAVEq81Y74WYlmEVkkXqNiJSFW/e+eFd/xCAlmEabyI7a0JI iTbpZWUgIeCle3NLGCV50BNXGgO5rz5VCyi5MopTWlP2Bg4lT+/Y6sWIjs9lClq7TuXo /LFtTI9aFCPKh/CTdhh1hbmoMAUTUvr1OUfrk0YFiSOg/OauJhuZA1cxzKoxAAObH0NK yAAOFUGQ4/2r9IAav9h871MaC8z57Ujty+QQgO6y4UkQYsYOVlByrDU9dEd1qJYiA7Zz +wxA== X-Forwarded-Encrypted: i=1; AKwUvBw4HaRH0Fec2BlJwQRYNlUJWwrXpMCSxyYPV2c3AWJoD5tjdbCsKRXpaLUddDTyytoka5Qnz9kvjTFtmBM=@vger.kernel.org X-Gm-Message-State: AFuF++nI7qebEmTtVpqjIY0q+gbtcwLIhwlDk7MmCF+0mfINBJiNqmky A6wP7yqVG3HwtZEUjz4+7rHTMyr9jaacs6xqsne6lgnbUVXlClbP8Nf/ X-Gm-Gg: AYBFou1AP2umty/BKv1NMTGN9XEP2F7iOTntwuGUNj23UmWvdnDk2tkZe//sbaWyFzs 3uKPzYxjtYrBQ+V8DOiPefto7g6YckzTAdTalz0gZ4S4TZHgZzGcwNmPSV+ox+XLLyQ5lfzWsI1 RGYaUJy2swvviSrp2LqBJyU7k3zTRnQ6dmZvK5Vp5Im7TTttOUvL7xSMA58RfvWt4xnY4ntq/Fh r1wDMHAFoTeaZ/09Kc6mS975XsTNWc16V+TIJ1IW1ZswpSF+rnMAgddDaVb5x3BOClphUzYDC0G 3A+oOMkGEaMPnku/mFlQXKHm0L+2gT5BsK5c0UUoLwedIL/J12WGH8C3xGGlK/GiOsdj5nMuour L6EQwipIcO6c75TqcRpcMVaKkidgFWjjvjBygGnZdVkRtesd7Xul5juvzJti10K+UGvlIx+53t4 4rwYuu4y0yt8IzCe7s3WSaFmtHEGTg/JyPdkWDuQTl/hVLnJ9KFhShGcnk3qJyHQ== X-Received: by 2002:a17:90b:2e48:b0:380:71eb:4014 with SMTP id 98e67ed59e1d1-396d0feda32mr18850877a91.15.1787966352081; Fri, 28 Aug 2026 18:19:12 -0700 (PDT) Received: from tradnomic.. ([2601:646:8300:7570:a9a6:70a4:308d:c424]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-142e41837c6sm6833167c88.11.2026.08.28.18.19.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Aug 2026 18:19:11 -0700 (PDT) From: Rafael Alejandro Diaz Cruz To: gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Rafael Alejandro Diaz Cruz , syzbot+4a5c87a01894ca37f25c@syzkaller.appspotmail.com Subject: [PATCH usb-next v2] USB: gadgetfs: Fix use-after-free in gadgetfs_kill_sb Date: Fri, 28 Aug 2026 18:19:01 -0700 Message-ID: <20260829011901.325379-1-rafad900@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When gadgetfs_fill_super() fails, it's error path calls put_dev() which drops refcount inside the_device to 0 and frees the objet. But the_device pointer is not cleared, leading to point at freed memory. VFS will then call gadgetfs_kill_sb() after mount failure leading to put_dev() to be called on the already freed pointer. Fix by setting the_device = NULL during error path before calling put_dev() inside gadgetfs_fill_super() so that gadgetfs_kill_sb() skips put_dev(). However, if the fault injection from syzbot failed and it began the open()/write()/close()/unmount() sequence then close() and umount() will each trigger the refcount to drop once via put_dev(). This will still cause UAF since refcount is only incremented once on creation but decremented twice. Reported-by: syzbot+4a5c87a01894ca37f25c@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=4a5c87a01894ca37f25c Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Rafael Alejandro Diaz Cruz --- drivers/usb/gadget/legacy/inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c index d87a8ab51510..77efa984ce84 100644 --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -2059,6 +2059,7 @@ gadgetfs_fill_super (struct super_block *sb, struct fs_context *fc) rc = gadgetfs_create_file(sb, CHIP, dev, &ep0_operations); if (rc) { put_dev(dev); + the_device = NULL; goto Enomem; } @@ -2066,6 +2067,7 @@ gadgetfs_fill_super (struct super_block *sb, struct fs_context *fc) * from binding to a controller. */ the_device = dev; + get_dev(dev); rc = 0; goto Done; -- 2.43.0