6.6-stable review patch. If anyone has any objections, please let me know.
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From: Kuen-Han Tsai khtsai@google.com
[ Upstream commit 75a5b8d4ddd4eb6b16cb0b475d14ff4ae64295ef ]
After an bind/unbind cycle, the ncm->notify_req is left stale. If a subsequent bind fails, the unified error label attempts to free this stale request, leading to a NULL pointer dereference when accessing ep->ops->free_request.
Refactor the error handling in the bind path to use the __free() automatic cleanup mechanism.
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020 Call trace: usb_ep_free_request+0x2c/0xec ncm_bind+0x39c/0x3dc usb_add_function+0xcc/0x1f0 configfs_composite_bind+0x468/0x588 gadget_bind_driver+0x104/0x270 really_probe+0x190/0x374 __driver_probe_device+0xa0/0x12c driver_probe_device+0x3c/0x218 __device_attach_driver+0x14c/0x188 bus_for_each_drv+0x10c/0x168 __device_attach+0xfc/0x198 device_initial_probe+0x14/0x24 bus_probe_device+0x94/0x11c device_add+0x268/0x48c usb_add_gadget+0x198/0x28c dwc3_gadget_init+0x700/0x858 __dwc3_set_mode+0x3cc/0x664 process_scheduled_works+0x1d8/0x488 worker_thread+0x244/0x334 kthread+0x114/0x1bc ret_from_fork+0x10/0x20
Fixes: 9f6ce4240a2b ("usb: gadget: f_ncm.c added") Cc: stable@kernel.org Signed-off-by: Kuen-Han Tsai khtsai@google.com Link: https://lore.kernel.org/r/20250916-ready-v1-3-4997bf277548@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Link: https://lore.kernel.org/r/20250916-ready-v1-3-4997bf277548@google.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/gadget/function/f_ncm.c | 78 +++++++++++++++--------------------- 1 file changed, 33 insertions(+), 45 deletions(-)
--- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -11,6 +11,7 @@ * Copyright (C) 2008 Nokia Corporation */
+#include <linux/cleanup.h> #include <linux/kernel.h> #include <linux/interrupt.h> #include <linux/module.h> @@ -19,6 +20,7 @@ #include <linux/crc32.h>
#include <linux/usb/cdc.h> +#include <linux/usb/gadget.h>
#include "u_ether.h" #include "u_ether_configfs.h" @@ -1422,18 +1424,18 @@ static int ncm_bind(struct usb_configura struct usb_ep *ep; struct f_ncm_opts *ncm_opts;
+ struct usb_os_desc_table *os_desc_table __free(kfree) = NULL; + struct usb_request *request __free(free_usb_request) = NULL; + if (!can_support_ecm(cdev->gadget)) return -EINVAL;
ncm_opts = container_of(f->fi, struct f_ncm_opts, func_inst);
if (cdev->use_os_string) { - f->os_desc_table = kzalloc(sizeof(*f->os_desc_table), - GFP_KERNEL); - if (!f->os_desc_table) + os_desc_table = kzalloc(sizeof(*os_desc_table), GFP_KERNEL); + if (!os_desc_table) return -ENOMEM; - f->os_desc_n = 1; - f->os_desc_table[0].os_desc = &ncm_opts->ncm_os_desc; }
mutex_lock(&ncm_opts->lock); @@ -1443,16 +1445,15 @@ static int ncm_bind(struct usb_configura mutex_unlock(&ncm_opts->lock);
if (status) - goto fail; + return status;
ncm_opts->bound = true;
us = usb_gstrings_attach(cdev, ncm_strings, ARRAY_SIZE(ncm_string_defs)); - if (IS_ERR(us)) { - status = PTR_ERR(us); - goto fail; - } + if (IS_ERR(us)) + return PTR_ERR(us); + ncm_control_intf.iInterface = us[STRING_CTRL_IDX].id; ncm_data_nop_intf.iInterface = us[STRING_DATA_IDX].id; ncm_data_intf.iInterface = us[STRING_DATA_IDX].id; @@ -1462,55 +1463,47 @@ static int ncm_bind(struct usb_configura /* allocate instance-specific interface IDs */ status = usb_interface_id(c, f); if (status < 0) - goto fail; + return status; ncm->ctrl_id = status; ncm_iad_desc.bFirstInterface = status;
ncm_control_intf.bInterfaceNumber = status; ncm_union_desc.bMasterInterface0 = status;
- if (cdev->use_os_string) - f->os_desc_table[0].if_id = - ncm_iad_desc.bFirstInterface; - status = usb_interface_id(c, f); if (status < 0) - goto fail; + return status; ncm->data_id = status;
ncm_data_nop_intf.bInterfaceNumber = status; ncm_data_intf.bInterfaceNumber = status; ncm_union_desc.bSlaveInterface0 = status;
- status = -ENODEV; - /* allocate instance-specific endpoints */ ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_in_desc); if (!ep) - goto fail; + return -ENODEV; ncm->port.in_ep = ep;
ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_out_desc); if (!ep) - goto fail; + return -ENODEV; ncm->port.out_ep = ep;
ep = usb_ep_autoconfig(cdev->gadget, &fs_ncm_notify_desc); if (!ep) - goto fail; + return -ENODEV; ncm->notify = ep;
- status = -ENOMEM; - /* allocate notification request and buffer */ - ncm->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL); - if (!ncm->notify_req) - goto fail; - ncm->notify_req->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL); - if (!ncm->notify_req->buf) - goto fail; - ncm->notify_req->context = ncm; - ncm->notify_req->complete = ncm_notify_complete; + request = usb_ep_alloc_request(ep, GFP_KERNEL); + if (!request) + return -ENOMEM; + request->buf = kmalloc(NCM_STATUS_BYTECOUNT, GFP_KERNEL); + if (!request->buf) + return -ENOMEM; + request->context = ncm; + request->complete = ncm_notify_complete;
/* * support all relevant hardware speeds... we expect that when @@ -1530,7 +1523,7 @@ static int ncm_bind(struct usb_configura status = usb_assign_descriptors(f, ncm_fs_function, ncm_hs_function, ncm_ss_function, ncm_ss_function); if (status) - goto fail; + return status;
/* * NOTE: all that is done without knowing or caring about @@ -1544,23 +1537,18 @@ static int ncm_bind(struct usb_configura hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT); ncm->task_timer.function = ncm_tx_timeout;
+ if (cdev->use_os_string) { + os_desc_table[0].os_desc = &ncm_opts->ncm_os_desc; + os_desc_table[0].if_id = ncm_iad_desc.bFirstInterface; + f->os_desc_table = no_free_ptr(os_desc_table); + f->os_desc_n = 1; + } + ncm->notify_req = no_free_ptr(request); + DBG(cdev, "CDC Network: IN/%s OUT/%s NOTIFY/%s\n", ncm->port.in_ep->name, ncm->port.out_ep->name, ncm->notify->name); return 0; - -fail: - kfree(f->os_desc_table); - f->os_desc_n = 0; - - if (ncm->notify_req) { - kfree(ncm->notify_req->buf); - usb_ep_free_request(ncm->notify, ncm->notify_req); - } - - ERROR(cdev, "%s: can't bind, err %d\n", f->name, status); - - return status; }
static inline struct f_ncm_opts *to_f_ncm_opts(struct config_item *item)