| From e7ac6c6666bec0a354758a1298d3231e4a635362 Mon Sep 17 00:00:00 2001 |
| From: "Seymour, Shane M" <shane.seymour@hp.com> |
| Date: Thu, 2 Jul 2015 12:01:10 +0000 |
| Subject: st: null pointer dereference panic caused by use after kref_put by st_open |
| MIME-Version: 1.0 |
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| |
| From: "Seymour, Shane M" <shane.seymour@hp.com> |
| |
| commit e7ac6c6666bec0a354758a1298d3231e4a635362 upstream. |
| |
| Two SLES11 SP3 servers encountered similar crashes simultaneously |
| following some kind of SAN/tape target issue: |
| |
| ... |
| qla2xxx [0000:81:00.0]-801c:3: Abort command issued nexus=3:0:2 -- 1 2002. |
| qla2xxx [0000:81:00.0]-801c:3: Abort command issued nexus=3:0:2 -- 1 2002. |
| qla2xxx [0000:81:00.0]-8009:3: DEVICE RESET ISSUED nexus=3:0:2 cmd=ffff882f89c2c7c0. |
| qla2xxx [0000:81:00.0]-800c:3: do_reset failed for cmd=ffff882f89c2c7c0. |
| qla2xxx [0000:81:00.0]-800f:3: DEVICE RESET FAILED: Task management failed nexus=3:0:2 cmd=ffff882f89c2c7c0. |
| qla2xxx [0000:81:00.0]-8009:3: TARGET RESET ISSUED nexus=3:0:2 cmd=ffff882f89c2c7c0. |
| qla2xxx [0000:81:00.0]-800c:3: do_reset failed for cmd=ffff882f89c2c7c0. |
| qla2xxx [0000:81:00.0]-800f:3: TARGET RESET FAILED: Task management failed nexus=3:0:2 cmd=ffff882f89c2c7c0. |
| qla2xxx [0000:81:00.0]-8012:3: BUS RESET ISSUED nexus=3:0:2. |
| qla2xxx [0000:81:00.0]-802b:3: BUS RESET SUCCEEDED nexus=3:0:2. |
| qla2xxx [0000:81:00.0]-505f:3: Link is operational (8 Gbps). |
| qla2xxx [0000:81:00.0]-8018:3: ADAPTER RESET ISSUED nexus=3:0:2. |
| qla2xxx [0000:81:00.0]-00af:3: Performing ISP error recovery - ha=ffff88bf04d18000. |
| rport-3:0-0: blocked FC remote port time out: removing target and saving binding |
| qla2xxx [0000:81:00.0]-505f:3: Link is operational (8 Gbps). |
| qla2xxx [0000:81:00.0]-8017:3: ADAPTER RESET SUCCEEDED nexus=3:0:2. |
| rport-2:0-0: blocked FC remote port time out: removing target and saving binding |
| sg_rq_end_io: device detached |
| BUG: unable to handle kernel NULL pointer dereference at 00000000000002a8 |
| IP: [<ffffffff8133b268>] __pm_runtime_idle+0x28/0x90 |
| PGD 7e6586f067 PUD 7e5af06067 PMD 0 [1739975.390354] Oops: 0002 [#1] SMP |
| CPU 0 |
| ... |
| Supported: No, Proprietary modules are loaded [1739975.390463] |
| Pid: 27965, comm: ABCD Tainted: PF X 3.0.101-0.29-default #1 HP ProLiant DL580 Gen8 |
| RIP: 0010:[<ffffffff8133b268>] [<ffffffff8133b268>] __pm_runtime_idle+0x28/0x90 |
| RSP: 0018:ffff8839dc1e7c68 EFLAGS: 00010202 |
| RAX: 0000000000000000 RBX: ffff883f0592fc00 RCX: 0000000000000090 |
| RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000138 |
| RBP: 0000000000000138 R08: 0000000000000010 R09: ffffffff81bd39d0 |
| R10: 00000000000009c0 R11: ffffffff81025790 R12: 0000000000000001 |
| R13: ffff883022212b80 R14: 0000000000000004 R15: ffff883022212b80 |
| FS: 00007f8e54560720(0000) GS:ffff88407f800000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b |
| CR2: 00000000000002a8 CR3: 0000007e6ced6000 CR4: 00000000001407f0 |
| DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 |
| Process ABCD (pid: 27965, threadinfo ffff8839dc1e6000, task ffff883592e0c640) |
| Stack: |
| ffff883f0592fc00 00000000fffffffa 0000000000000001 ffff883022212b80 |
| ffff883eff772400 ffffffffa03fa309 0000000000000000 0000000000000000 |
| ffffffffa04003a0 ffff883f063196c0 ffff887f0379a930 ffffffff8115ea1e |
| Call Trace: |
| [<ffffffffa03fa309>] st_open+0x129/0x240 [st] |
| [<ffffffff8115ea1e>] chrdev_open+0x13e/0x200 |
| [<ffffffff811588a8>] __dentry_open+0x198/0x310 |
| [<ffffffff81167d74>] do_last+0x1f4/0x800 |
| [<ffffffff81168fe9>] path_openat+0xd9/0x420 |
| [<ffffffff8116946c>] do_filp_open+0x4c/0xc0 |
| [<ffffffff8115a00f>] do_sys_open+0x17f/0x250 |
| [<ffffffff81468d92>] system_call_fastpath+0x16/0x1b |
| [<00007f8e4f617fd0>] 0x7f8e4f617fcf |
| Code: eb d3 90 48 83 ec 28 40 f6 c6 04 48 89 6c 24 08 4c 89 74 24 20 48 89 fd 48 89 1c 24 4c 89 64 24 10 41 89 f6 4c 89 6c 24 18 74 11 <f0> ff 8f 70 01 00 00 0f 94 c0 45 31 ed 84 c0 74 2b 4c 8d a5 a0 |
| RIP [<ffffffff8133b268>] __pm_runtime_idle+0x28/0x90 |
| RSP <ffff8839dc1e7c68> |
| CR2: 00000000000002a8 |
| |
| Analysis reveals the cause of the crash to be due to STp->device |
| being NULL. The pointer was NULLed via scsi_tape_put(STp) when it |
| calls scsi_tape_release(). In st_open() we jump to err_out after |
| scsi_block_when_processing_errors() completes and returns the |
| device as offline (sdev_state was SDEV_DEL): |
| |
| 1180 /* Open the device. Needs to take the BKL only because of incrementing the SCSI host |
| 1181 module count. */ |
| 1182 static int st_open(struct inode *inode, struct file *filp) |
| 1183 { |
| 1184 int i, retval = (-EIO); |
| 1185 int resumed = 0; |
| 1186 struct scsi_tape *STp; |
| 1187 struct st_partstat *STps; |
| 1188 int dev = TAPE_NR(inode); |
| 1189 char *name; |
| ... |
| 1217 if (scsi_autopm_get_device(STp->device) < 0) { |
| 1218 retval = -EIO; |
| 1219 goto err_out; |
| 1220 } |
| 1221 resumed = 1; |
| 1222 if (!scsi_block_when_processing_errors(STp->device)) { |
| 1223 retval = (-ENXIO); |
| 1224 goto err_out; |
| 1225 } |
| ... |
| 1264 err_out: |
| 1265 normalize_buffer(STp->buffer); |
| 1266 spin_lock(&st_use_lock); |
| 1267 STp->in_use = 0; |
| 1268 spin_unlock(&st_use_lock); |
| 1269 scsi_tape_put(STp); <-- STp->device = 0 after this |
| 1270 if (resumed) |
| 1271 scsi_autopm_put_device(STp->device); |
| 1272 return retval; |
| |
| The ref count for the struct scsi_tape had already been reduced |
| to 1 when the .remove method of the st module had been called. |
| The kref_put() in scsi_tape_put() caused scsi_tape_release() |
| to be called: |
| |
| 0266 static void scsi_tape_put(struct scsi_tape *STp) |
| 0267 { |
| 0268 struct scsi_device *sdev = STp->device; |
| 0269 |
| 0270 mutex_lock(&st_ref_mutex); |
| 0271 kref_put(&STp->kref, scsi_tape_release); <-- calls this |
| 0272 scsi_device_put(sdev); |
| 0273 mutex_unlock(&st_ref_mutex); |
| 0274 } |
| |
| In scsi_tape_release() the struct scsi_device in the struct |
| scsi_tape gets set to NULL: |
| |
| 4273 static void scsi_tape_release(struct kref *kref) |
| 4274 { |
| 4275 struct scsi_tape *tpnt = to_scsi_tape(kref); |
| 4276 struct gendisk *disk = tpnt->disk; |
| 4277 |
| 4278 tpnt->device = NULL; <<<---- where the dev is nulled |
| 4279 |
| 4280 if (tpnt->buffer) { |
| 4281 normalize_buffer(tpnt->buffer); |
| 4282 kfree(tpnt->buffer->reserved_pages); |
| 4283 kfree(tpnt->buffer); |
| 4284 } |
| 4285 |
| 4286 disk->private_data = NULL; |
| 4287 put_disk(disk); |
| 4288 kfree(tpnt); |
| 4289 return; |
| 4290 } |
| |
| Although the problem was reported on SLES11.3 the problem appears |
| in linux-next as well. |
| |
| The crash is fixed by reordering the code so we no longer access |
| the struct scsi_tape after the kref_put() is done on it in st_open(). |
| |
| Signed-off-by: Shane Seymour <shane.seymour@hp.com> |
| Signed-off-by: Darren Lavender <darren.lavender@hp.com> |
| Reviewed-by: Johannes Thumshirn <jthumshirn@suse.com> |
| Acked-by: Kai Mรคkisara <kai.makisara@kolumbus.fi> |
| Signed-off-by: James Bottomley <JBottomley@Odin.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/scsi/st.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/scsi/st.c |
| +++ b/drivers/scsi/st.c |
| @@ -1262,9 +1262,9 @@ static int st_open(struct inode *inode, |
| spin_lock(&st_use_lock); |
| STp->in_use = 0; |
| spin_unlock(&st_use_lock); |
| - scsi_tape_put(STp); |
| if (resumed) |
| scsi_autopm_put_device(STp->device); |
| + scsi_tape_put(STp); |
| return retval; |
| |
| } |