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| author | Calvin Owens <calvinowens@fb.com> | 2016-05-13 22:28:21 +0200 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2016-08-12 23:40:51 +0200 |
| commit | e120dcb6b2a11840b08f0fc0d2e90256b7b6e842 (patch) | |
| tree | 03ee7f65770d472448885e3f16b74408d1615015 /drivers/scsi/ses.c | |
| parent | mpt3sas: Fix resume on WarpDrive flash cards (diff) | |
| download | linux-e120dcb6b2a11840b08f0fc0d2e90256b7b6e842.tar.xz linux-e120dcb6b2a11840b08f0fc0d2e90256b7b6e842.zip | |
ses: Fix racy cleanup of /sys in remove_dev()
Currently we free the resources backing the enclosure device before we
call device_unregister(). This is racy: during rmmod of low-level SCSI
drivers that hook into enclosure, we end up with a small window of time
during which writing to /sys can OOPS. Example trace with mpt3sas:
general protection fault: 0000 [#1] SMP KASAN
Modules linked in: mpt3sas(-) <...>
RIP: [<ffffffffa0388a98>] ses_get_page2_descriptor.isra.6+0x38/0x220 [ses]
Call Trace:
[<ffffffffa0389d14>] ses_set_fault+0xf4/0x400 [ses]
[<ffffffffa0361069>] set_component_fault+0xa9/0xf0 [enclosure]
[<ffffffff8205bffc>] dev_attr_store+0x3c/0x70
[<ffffffff81677df5>] sysfs_kf_write+0x115/0x180
[<ffffffff81675725>] kernfs_fop_write+0x275/0x3a0
[<ffffffff8151f810>] __vfs_write+0xe0/0x3e0
[<ffffffff8152281f>] vfs_write+0x13f/0x4a0
[<ffffffff81526731>] SyS_write+0x111/0x230
[<ffffffff828b401b>] entry_SYSCALL_64_fastpath+0x13/0x94
Fortunately the solution is extremely simple: call device_unregister()
before we free the resources, and the race no longer exists. The driver
core holds a reference over ->remove_dev(), so AFAICT this is safe.
Signed-off-by: Calvin Owens <calvinowens@fb.com>
Reviewed-by: James Bottomley <jejb@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/ses.c')
| -rw-r--r-- | drivers/scsi/ses.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c index 53ef1cb6418e..0e8601aa877a 100644 --- a/drivers/scsi/ses.c +++ b/drivers/scsi/ses.c @@ -778,6 +778,8 @@ static void ses_intf_remove_enclosure(struct scsi_device *sdev) if (!edev) return; + enclosure_unregister(edev); + ses_dev = edev->scratch; edev->scratch = NULL; @@ -789,7 +791,6 @@ static void ses_intf_remove_enclosure(struct scsi_device *sdev) kfree(edev->component[0].scratch); put_device(&edev->edev); - enclosure_unregister(edev); } static void ses_intf_remove(struct device *cdev, |