| Message ID | 1596185878-24360-1-git-send-email-macpaul.lin@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] usb: mtu3: fix panic in mtu3_gadget_disconnect() | expand |
On Fri, Jul 31, 2020 at 04:57:58PM +0800, Macpaul Lin wrote: > This patch fixes a possible issue when mtu3_gadget_stop() > already assigned NULL to mtu->gadget_driver during mtu_gadget_disconnect(). > > Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com> > Cc: stable@vger.kernel.org > --- > Changes for v2: > - Check mtu_gadget_driver out of spin_lock might still not work. > We use a temporary pointer to keep the callback function. > > drivers/usb/mtu3/mtu3_gadget.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c > index 68ea4395f871..40cb6626f496 100644 > --- a/drivers/usb/mtu3/mtu3_gadget.c > +++ b/drivers/usb/mtu3/mtu3_gadget.c > @@ -840,10 +840,17 @@ void mtu3_gadget_suspend(struct mtu3 *mtu) > /* called when VBUS drops below session threshold, and in other cases */ > void mtu3_gadget_disconnect(struct mtu3 *mtu) > { > + struct usb_gadget_driver *driver; > + > dev_dbg(mtu->dev, "gadget DISCONNECT\n"); > if (mtu->gadget_driver && mtu->gadget_driver->disconnect) { > + driver = mtu->gadget_driver; > spin_unlock(&mtu->lock); > - mtu->gadget_driver->disconnect(&mtu->g); > + /* > + * avoid kernel panic because mtu3_gadget_stop() assigned NULL > + * to mtu->gadget_driver. > + */ > + driver->disconnect(&mtu->g); > spin_lock(&mtu->lock); > } This is not the right approach; it might race with the gadget driver unregistering itself. Instead, mtu3_gadget_stop() should call synchronize_irq() after releasing the IRQ line. When synchronize_irq() returns, you'll know any IRQ handlers have finished running, so you won't receive any more disconnect notifications. Then it will be safe to acquire the spinlock and set mtu->gadget_driver to NULL. Alan Stern
diff --git a/drivers/usb/mtu3/mtu3_gadget.c b/drivers/usb/mtu3/mtu3_gadget.c index 68ea4395f871..40cb6626f496 100644 --- a/drivers/usb/mtu3/mtu3_gadget.c +++ b/drivers/usb/mtu3/mtu3_gadget.c @@ -840,10 +840,17 @@ void mtu3_gadget_suspend(struct mtu3 *mtu) /* called when VBUS drops below session threshold, and in other cases */ void mtu3_gadget_disconnect(struct mtu3 *mtu) { + struct usb_gadget_driver *driver; + dev_dbg(mtu->dev, "gadget DISCONNECT\n"); if (mtu->gadget_driver && mtu->gadget_driver->disconnect) { + driver = mtu->gadget_driver; spin_unlock(&mtu->lock); - mtu->gadget_driver->disconnect(&mtu->g); + /* + * avoid kernel panic because mtu3_gadget_stop() assigned NULL + * to mtu->gadget_driver. + */ + driver->disconnect(&mtu->g); spin_lock(&mtu->lock); }
This patch fixes a possible issue when mtu3_gadget_stop() already assigned NULL to mtu->gadget_driver during mtu_gadget_disconnect(). [<ffffff9008161974>] notifier_call_chain+0xa4/0x128 [<ffffff9008161fd4>] __atomic_notifier_call_chain+0x84/0x138 [<ffffff9008162ec0>] notify_die+0xb0/0x120 [<ffffff900809e340>] die+0x1f8/0x5d0 [<ffffff90080d03b4>] __do_kernel_fault+0x19c/0x280 [<ffffff90080d04dc>] do_bad_area+0x44/0x140 [<ffffff90080d0f9c>] do_translation_fault+0x4c/0x90 [<ffffff9008080a78>] do_mem_abort+0xb8/0x258 [<ffffff90080849d0>] el1_da+0x24/0x3c [<ffffff9009bde01c>] mtu3_gadget_disconnect+0xac/0x128 [<ffffff9009bd576c>] mtu3_irq+0x34c/0xc18 [<ffffff90082ac03c>] __handle_irq_event_percpu+0x2ac/0xcd0 [<ffffff90082acae0>] handle_irq_event_percpu+0x80/0x138 [<ffffff90082acc44>] handle_irq_event+0xac/0x148 [<ffffff90082b71cc>] handle_fasteoi_irq+0x234/0x568 [<ffffff90082a8708>] generic_handle_irq+0x48/0x68 [<ffffff90082a96ac>] __handle_domain_irq+0x264/0x1740 [<ffffff90080819f4>] gic_handle_irq+0x14c/0x250 [<ffffff9008084cec>] el1_irq+0xec/0x194 [<ffffff90085b985c>] dma_pool_alloc+0x6e4/0xae0 [<ffffff9008d7f890>] cmdq_mbox_pool_alloc_impl+0xb0/0x238 [<ffffff9008d80904>] cmdq_pkt_alloc_buf+0x2dc/0x7c0 [<ffffff9008d80f60>] cmdq_pkt_add_cmd_buffer+0x178/0x270 [<ffffff9008d82320>] cmdq_pkt_perf_begin+0x108/0x148 [<ffffff9008d824d8>] cmdq_pkt_create+0x178/0x1f0 [<ffffff9008f96230>] mtk_crtc_config_default_path+0x328/0x7a0 [<ffffff90090246cc>] mtk_drm_idlemgr_kick+0xa6c/0x1460 [<ffffff9008f9bbb4>] mtk_drm_crtc_atomic_begin+0x1a4/0x1a68 [<ffffff9008e8df9c>] drm_atomic_helper_commit_planes+0x154/0x878 [<ffffff9008f2fb70>] mtk_atomic_complete.isra.16+0xe80/0x19c8 [<ffffff9008f30910>] mtk_atomic_commit+0x258/0x898 [<ffffff9008ef142c>] drm_atomic_commit+0xcc/0x108 [<ffffff9008ef7cf0>] drm_mode_atomic_ioctl+0x1c20/0x2580 [<ffffff9008ebc768>] drm_ioctl_kernel+0x118/0x1b0 [<ffffff9008ebcde8>] drm_ioctl+0x5c0/0x920 [<ffffff900863b030>] do_vfs_ioctl+0x188/0x1820 [<ffffff900863c754>] SyS_ioctl+0x8c/0xa0 Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com> Cc: stable@vger.kernel.org --- Changes for v2: - Check mtu_gadget_driver out of spin_lock might still not work. We use a temporary pointer to keep the callback function. drivers/usb/mtu3/mtu3_gadget.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)