| Message ID | 1541725843-2019-1-git-send-email-manjunath.b.patil@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] xen-blkfront: fix kernel panic with blkfront_remove() | expand |
On 09/11/2018 02:10, Manjunath Patil wrote: > When we try to detach the device, blkfront_remove() tries to access > blkfront_info leading to kernel panic. > > Typical call stack involving panic - > #10 page_fault at ffffffff816f25df > [exception RIP: blkif_free+46] > #11 blkfront_remove at ffffffffa004de47 [xen_blkfront] > #12 xenbus_dev_remove at ffffffff813faa4c > #13 __device_release_driver at ffffffff814769aa > #14 device_release_driver at ffffffff81476a63 > #15 bus_remove_device at ffffffff814762eb > #16 device_del at ffffffff81472684 > #17 device_unregister at ffffffff814727e2 > #18 xenbus_dev_changed at ffffffff813fa89f > #19 frontend_changed at ffffffff813fca19 > #20 xenwatch_thread at ffffffff813f88f9 > #21 kthread at ffffffff810a486b > #22 ret_from_fork at ffffffff816ed2a8 > > Cc: stable@vger.kernel.org > Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com> Commit f92898e7f32e3 already added that. Juergen
oops! sorry for not noticing this. -Manjunath On 11/8/2018 10:16 PM, Juergen Gross wrote: > On 09/11/2018 02:10, Manjunath Patil wrote: >> When we try to detach the device, blkfront_remove() tries to access >> blkfront_info leading to kernel panic. >> >> Typical call stack involving panic - >> #10 page_fault at ffffffff816f25df >> [exception RIP: blkif_free+46] >> #11 blkfront_remove at ffffffffa004de47 [xen_blkfront] >> #12 xenbus_dev_remove at ffffffff813faa4c >> #13 __device_release_driver at ffffffff814769aa >> #14 device_release_driver at ffffffff81476a63 >> #15 bus_remove_device at ffffffff814762eb >> #16 device_del at ffffffff81472684 >> #17 device_unregister at ffffffff814727e2 >> #18 xenbus_dev_changed at ffffffff813fa89f >> #19 frontend_changed at ffffffff813fca19 >> #20 xenwatch_thread at ffffffff813f88f9 >> #21 kthread at ffffffff810a486b >> #22 ret_from_fork at ffffffff816ed2a8 >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com> > Commit f92898e7f32e3 already added that. > > > Juergen
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index dc8fe25..2d8b10d 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -2496,6 +2496,9 @@ static int blkfront_remove(struct xenbus_device *xbdev) dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); + if (!info) + return 0; + blkif_free(info, 0); mutex_lock(&info->mutex);
When we try to detach the device, blkfront_remove() tries to access blkfront_info leading to kernel panic. Typical call stack involving panic - #10 page_fault at ffffffff816f25df [exception RIP: blkif_free+46] #11 blkfront_remove at ffffffffa004de47 [xen_blkfront] #12 xenbus_dev_remove at ffffffff813faa4c #13 __device_release_driver at ffffffff814769aa #14 device_release_driver at ffffffff81476a63 #15 bus_remove_device at ffffffff814762eb #16 device_del at ffffffff81472684 #17 device_unregister at ffffffff814727e2 #18 xenbus_dev_changed at ffffffff813fa89f #19 frontend_changed at ffffffff813fca19 #20 xenwatch_thread at ffffffff813f88f9 #21 kthread at ffffffff810a486b #22 ret_from_fork at ffffffff816ed2a8 Cc: stable@vger.kernel.org Signed-off-by: Manjunath Patil <manjunath.b.patil@oracle.com> --- v2: style change. added the missing space b/w if and ( --- drivers/block/xen-blkfront.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)