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Vladislav Bolkhovitin
8ce28aaba2
The sysfs attributes of a target can be accessed before scst_tgt.tgt_priv has been set. Avoid that such an access triggers a crash. Symptom: BUG: unable to handle kernel NULL pointer dereference at 000000000000004c IP: [<ffffffffa1345848>] iscsi_is_target_enabled+0x8/0x20 [iscsi_scst] PGD 150a4c067 PUD 13cacb067 PMD 0 Oops: 0000 [#1] SMP CPU 1 Modules linked in: zfs(P) iscsi_scst(O) scst_vdisk(O) scst(O) zcommon(P) znvpair(P) zavl(P) zunicode(P) spl(O) [last unloaded: zfs] Pid: 3974, comm: scst_uid1864 Tainted: P O 3.2.23-zfsiscsi-std-ipv6-64 #3 Supermicro X6DVA/X6DVA RIP: 0010:[<ffffffffa1345848>] [<ffffffffa1345848>] iscsi_is_target_enabled+0x8/0x20 [iscsi_scst] RSP: 0018:ffff88015071ddc0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff880181fdaa00 RCX: ffff88012d41f380 RDX: ffff88015071c010 RSI: 0000000000000000 RDI: ffff880181fdaa00 RBP: ffff88015071ddc0 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffa134a608 R13: 0000000000000000 R14: 0000000000000129 R15: ffffffffa134a4c0 FS: 0000000000000000(0000) GS:ffff88019fc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 000000000000004c CR3: 0000000151927000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process scst_uid1864 (pid: 3974, threadinfo ffff88015071c000, task ffff880194d57500) Stack: ffff88015071de10 ffffffffa12ee89a 00000000fffffffc 01ff88015071de98 ffff88015071de80 ffff8801932a48d8 00000000fffffffc ffff88015071de98 ffff88015071de80 ffff880194d57500 ffff88015071de30 ffffffffa12f582e Call Trace: [<ffffffffa12ee89a>] __scst_is_relative_target_port_id_unique+0x6a/0xc0 [scst] [<ffffffffa12f582e>] gen_relative_target_port_id+0x6e/0xd0 [scst] [<ffffffffa12fdb8a>] scst_tgt_enable_store_work_fn+0x3a/0xe0 [scst] [<ffffffffa12f9397>] sysfs_work_thread_fn+0xc7/0x2e0 [scst] [<ffffffffa12f92d0>] ? scst_tgtt_release+0x20/0x20 [scst] [<ffffffffa12f92d0>] ? scst_tgtt_release+0x20/0x20 [scst] [<ffffffff810b44f6>] kthread+0x96/0xa0 [<ffffffff81b8ed74>] kernel_thread_helper+0x4/0x10 [<ffffffff810b4460>] ? kthread_worker_fn+0x180/0x180 [<ffffffff81b8ed70>] ? gs_change+0xb/0xb Code: 42 c8 74 0f 39 78 48 75 ea c9 c3 0f 1f 84 00 00 00 00 00 31 c0 c9 c3 66 66 66 2e 0f 1f 84 00 00 00 00 00 48 8b 47 48 55 48 89 e5 <0f> b6 40 4c c9 83 e0 01 c3 66 66 66 66 66 66 2e 0f 1f 84 00 00 RIP [<ffffffffa1345848>] iscsi_is_target_enabled+0x8/0x20 [iscsi_scst] RSP <ffff88015071ddc0> CR2: 000000000000004c ---[ end trace 6311d4069703be07 ]--- Reported-by: Etienne Dechamps <e-t172@akegroup.org> Signed-off-by: Bart Van Assche <bvanassche@acm.org> with some modifications git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@4515 d57e44dd-8a1f-0410-8b47-8ef2f437770f