commit 4cfbca86f6a8b801f3254e0e3c8f2b1d2d64be2b upstream.
Considering that in some extreme cases,
when u_serial driver is accessed by multiple threads,
Thread A is executing the open operation and calling the gs_open,
Thread B is executing the disconnect operation and calling the
gserial_disconnect function,The port->port_usb pointer will be set to NULL.
E.g.
Thread A Thread B
gs_open() gadget_unbind_driver()
gs_start_io() composite_disconnect()
gs_start_rx() gserial_disconnect()
... ...
spin_unlock(&port->port_lock)
status = usb_ep_queue() spin_lock(&port->port_lock)
spin_lock(&port->port_lock) port->port_usb = NULL
gs_free_requests(port->port_usb->in) spin_unlock(&port->port_lock)
Crash
This causes thread A to access a null pointer (port->port_usb is null)
when calling the gs_free_requests function, causing a crash.
If port_usb is NULL, the release request will be skipped as it
will be done by gserial_disconnect.
So add a null pointer check to gs_start_io before attempting
to access the value of the pointer port->port_usb.
Call trace:
gs_start_io+0x164/0x25c
gs_open+0x108/0x13c
tty_open+0x314/0x638
chrdev_open+0x1b8/0x258
do_dentry_open+0x2c4/0x700
vfs_open+0x2c/0x3c
path_openat+0xa64/0xc60
do_filp_open+0xb8/0x164
do_sys_openat2+0x84/0xf0
__arm64_sys_openat+0x70/0x9c
invoke_syscall+0x58/0x114
el0_svc_common+0x80/0xe0
do_el0_svc+0x1c/0x28
el0_svc+0x38/0x68
Fixes: c1dca562be8a ("usb gadget: split out serial core")
Cc: stable@vger.kernel.org
Suggested-by: Prashanth K <quic_prashk@quicinc.com>
Signed-off-by: Lianqin Hu <hulianqin@vivo.com>
Acked-by: Prashanth K <quic_prashk@quicinc.com>
Link: https://lore.kernel.org/r/TYUPR06MB62178DC3473F9E1A537DCD02D2362@TYUPR06MB6217.apcprd06.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5a444bea37e2759549ef72bfe83d1c8712e76b3d upstream.
Upstream commit aba3a8d01d62 ("usb: gadget: u_serial: add suspend
resume callbacks") added started_delayed flag, so that new ports
which are opened after USB suspend can start IO while resuming.
But if the port was already opened, and gadget suspend kicks in
afterwards, start_delayed will never be set. This causes resume
to bail out before calling gs_start_io(). Fix this by setting
start_delayed during suspend.
Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume callbacks")
Cc: stable@vger.kernel.org
Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
Link: https://lore.kernel.org/r/20240730125754.576326-1-quic_prashk@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
