st: null pointer dereference panic caused by use after kref_put by st_open
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 Mäkisara <kai.makisara@kolumbus.fi> Cc: stable@vger.kernel.org Signed-off-by: James Bottomley <JBottomley@Odin.com>
This commit is contained in:
Seymour, Shane M
James Bottomley
parent
bc0195aad0
commit
e7ac6c6666
|
|
@ -1329,9 +1329,9 @@ static int st_open(struct inode *inode, struct file *filp)
|
|||
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;
|
||||
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue