diff options
| author | Kuen-Han Tsai <khtsai@google.com> | 2026-03-11 17:12:15 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-11 14:29:56 +0200 |
| commit | 8ff689edfeceb5e3ec1623e09af2b2aa0f1098a8 (patch) | |
| tree | aecd32144d1573540e1be418d28e559f7d7bf6b2 | |
| parent | 854c6b49c2920139eecebc7245cca53d207a7b0d (diff) | |
usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop
commit e1eabb072c75681f78312c484ccfffb7430f206e upstream.
A race condition between gether_disconnect() and eth_stop() leads to a
NULL pointer dereference. Specifically, if eth_stop() is triggered
concurrently while gether_disconnect() is tearing down the endpoints,
eth_stop() attempts to access the cleared endpoint descriptor, causing
the following NPE:
Unable to handle kernel NULL pointer dereference
Call trace:
__dwc3_gadget_ep_enable+0x60/0x788
dwc3_gadget_ep_enable+0x70/0xe4
usb_ep_enable+0x60/0x15c
eth_stop+0xb8/0x108
Because eth_stop() crashes while holding the dev->lock, the thread
running gether_disconnect() fails to acquire the same lock and spins
forever, resulting in a hardlockup:
Core - Debugging Information for Hardlockup core(7)
Call trace:
queued_spin_lock_slowpath+0x94/0x488
_raw_spin_lock+0x64/0x6c
gether_disconnect+0x19c/0x1e8
ncm_set_alt+0x68/0x1a0
composite_setup+0x6a0/0xc50
The root cause is that the clearing of dev->port_usb in
gether_disconnect() is delayed until the end of the function.
Move the clearing of dev->port_usb to the very beginning of
gether_disconnect() while holding dev->lock. This cuts off the link
immediately, ensuring eth_stop() will see dev->port_usb as NULL and
safely bail out.
Fixes: 2b3d942c4878 ("usb ethernet gadget: split out network core")
Cc: stable <stable@kernel.org>
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20260311-gether-disconnect-npe-v1-1-454966adf7c7@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/u_ether.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index dabaa6669251..da07b9ff5d2c 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -1222,6 +1222,11 @@ void gether_disconnect(struct gether *link) DBG(dev, "%s\n", __func__); + spin_lock(&dev->lock); + dev->port_usb = NULL; + link->is_suspend = false; + spin_unlock(&dev->lock); + netif_stop_queue(dev->net); netif_carrier_off(dev->net); @@ -1259,11 +1264,6 @@ void gether_disconnect(struct gether *link) dev->header_len = 0; dev->unwrap = NULL; dev->wrap = NULL; - - spin_lock(&dev->lock); - dev->port_usb = NULL; - link->is_suspend = false; - spin_unlock(&dev->lock); } EXPORT_SYMBOL_GPL(gether_disconnect); |