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([2601:646:8300:7570:53eb:e6f6:37c3:14bb]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-396d22eacbfsm793778a91.0.2026.08.27.23.18.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Aug 2026 23:18:34 -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 v1] USB: gadgetfs: Fix use-after-free in gadgetfs_kill_sb Date: Thu, 27 Aug 2026 23:18:29 -0700 Message-ID: <20260828061829.566256-1-rafad900@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-usb@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(). 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