| Message ID | a76164e7-8d9f-37d5-8c2e-6733778d20da@kernel.dk (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On 04/11/2018 09:23 AM, Jens Axboe wrote: > We can't just use scsi_cd() to get the scsi_cd structure, we have > to grab a live reference to the device. For both callbacks, we're > not inside an open where we already hold a reference to the device. > > This fixes device removal/addition under concurrent device access, > which otherwise could result in the below oops. > > NULL pointer dereference at 0000000000000010 > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP > Modules linked in: > sr 12:0:0:0: [sr2] scsi-1 drive > scsi_debug crc_t10dif crct10dif_generic crct10dif_common nvme nvme_core sb_edac xl > sr 12:0:0:0: Attached scsi CD-ROM sr2 > sr_mod cdrom btrfs xor zstd_decompress zstd_compress xxhash lzo_compress zlib_defc > sr 12:0:0:0: Attached scsi generic sg7 type 5 > igb ahci libahci i2c_algo_bit libata dca [last unloaded: crc_t10dif] > CPU: 43 PID: 4629 Comm: systemd-udevd Not tainted 4.16.0+ #650 > Hardware name: Dell Inc. PowerEdge T630/0NT78X, BIOS 2.3.4 11/09/2016 > RIP: 0010:sr_block_revalidate_disk+0x23/0x190 [sr_mod] > RSP: 0018:ffff883ff357bb58 EFLAGS: 00010292 > RAX: ffffffffa00b07d0 RBX: ffff883ff3058000 RCX: ffff883ff357bb66 > RDX: 0000000000000003 RSI: 0000000000007530 RDI: ffff881fea631000 > RBP: 0000000000000000 R08: ffff881fe4d38400 R09: 0000000000000000 > R10: 0000000000000000 R11: 00000000000001b6 R12: 000000000800005d > R13: 000000000800005d R14: ffff883ffd9b3790 R15: 0000000000000000 > FS: 00007f7dc8e6d8c0(0000) GS:ffff883fff340000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000010 CR3: 0000003ffda98005 CR4: 00000000003606e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ? __invalidate_device+0x48/0x60 > check_disk_change+0x4c/0x60 > sr_block_open+0x16/0xd0 [sr_mod] > __blkdev_get+0xb9/0x450 > ? iget5_locked+0x1c0/0x1e0 > blkdev_get+0x11e/0x320 > ? bdget+0x11d/0x150 > ? _raw_spin_unlock+0xa/0x20 > ? bd_acquire+0xc0/0xc0 > do_dentry_open+0x1b0/0x320 > ? inode_permission+0x24/0xc0 > path_openat+0x4e6/0x1420 > ? cpumask_any_but+0x1f/0x40 > ? flush_tlb_mm_range+0xa0/0x120 > do_filp_open+0x8c/0xf0 > ? __seccomp_filter+0x28/0x230 > ? _raw_spin_unlock+0xa/0x20 > ? __handle_mm_fault+0x7d6/0x9b0 > ? list_lru_add+0xa8/0xc0 > ? _raw_spin_unlock+0xa/0x20 > ? __alloc_fd+0xaf/0x160 > ? do_sys_open+0x1a6/0x230 > do_sys_open+0x1a6/0x230 > do_syscall_64+0x5a/0x100 > entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > > --- > > diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c > index 0cf25d789d05..3f3cb72e0c0c 100644 > --- a/drivers/scsi/sr.c > +++ b/drivers/scsi/sr.c > @@ -587,18 +587,28 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, > static unsigned int sr_block_check_events(struct gendisk *disk, > unsigned int clearing) > { > - struct scsi_cd *cd = scsi_cd(disk); > + unsigned int ret = 0; > + struct scsi_cd *cd; > > - if (atomic_read(&cd->device->disk_events_disable_depth)) > + cd = scsi_cd_get(disk); > + if (!cd) > return 0; > > - return cdrom_check_events(&cd->cdi, clearing); > + if (!atomic_read(&cd->device->disk_events_disable_depth)) > + ret = cdrom_check_events(&cd->cdi, clearing); > + > + scsi_cd_put(cd); > + return ret; > } > > static int sr_block_revalidate_disk(struct gendisk *disk) > { > - struct scsi_cd *cd = scsi_cd(disk); > struct scsi_sense_hdr sshdr; > + struct scsi_cd *cd; > + > + cd = scsi_cd_get(disk); > + if (!cd) > + return -ENXIO; > > /* if the unit is not ready, nothing more to do */ > if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr)) > @@ -607,6 +617,7 @@ static int sr_block_revalidate_disk(struct gendisk *disk) > sr_cd_check(&cd->cdi); > get_sectorsize(cd); > out: > + scsi_cd_put(cd); > return 0; > } > > Reviewed-by: Lee Duncan <lduncan@suse.com>
On Wed 11-04-18 10:23:30, Jens Axboe wrote: > We can't just use scsi_cd() to get the scsi_cd structure, we have > to grab a live reference to the device. For both callbacks, we're > not inside an open where we already hold a reference to the device. > > This fixes device removal/addition under concurrent device access, > which otherwise could result in the below oops. > > NULL pointer dereference at 0000000000000010 > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP > Modules linked in: > sr 12:0:0:0: [sr2] scsi-1 drive > scsi_debug crc_t10dif crct10dif_generic crct10dif_common nvme nvme_core sb_edac xl > sr 12:0:0:0: Attached scsi CD-ROM sr2 > sr_mod cdrom btrfs xor zstd_decompress zstd_compress xxhash lzo_compress zlib_defc > sr 12:0:0:0: Attached scsi generic sg7 type 5 > igb ahci libahci i2c_algo_bit libata dca [last unloaded: crc_t10dif] > CPU: 43 PID: 4629 Comm: systemd-udevd Not tainted 4.16.0+ #650 > Hardware name: Dell Inc. PowerEdge T630/0NT78X, BIOS 2.3.4 11/09/2016 > RIP: 0010:sr_block_revalidate_disk+0x23/0x190 [sr_mod] > RSP: 0018:ffff883ff357bb58 EFLAGS: 00010292 > RAX: ffffffffa00b07d0 RBX: ffff883ff3058000 RCX: ffff883ff357bb66 > RDX: 0000000000000003 RSI: 0000000000007530 RDI: ffff881fea631000 > RBP: 0000000000000000 R08: ffff881fe4d38400 R09: 0000000000000000 > R10: 0000000000000000 R11: 00000000000001b6 R12: 000000000800005d > R13: 000000000800005d R14: ffff883ffd9b3790 R15: 0000000000000000 > FS: 00007f7dc8e6d8c0(0000) GS:ffff883fff340000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000010 CR3: 0000003ffda98005 CR4: 00000000003606e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ? __invalidate_device+0x48/0x60 > check_disk_change+0x4c/0x60 > sr_block_open+0x16/0xd0 [sr_mod] > __blkdev_get+0xb9/0x450 > ? iget5_locked+0x1c0/0x1e0 > blkdev_get+0x11e/0x320 > ? bdget+0x11d/0x150 > ? _raw_spin_unlock+0xa/0x20 > ? bd_acquire+0xc0/0xc0 > do_dentry_open+0x1b0/0x320 > ? inode_permission+0x24/0xc0 > path_openat+0x4e6/0x1420 > ? cpumask_any_but+0x1f/0x40 > ? flush_tlb_mm_range+0xa0/0x120 > do_filp_open+0x8c/0xf0 > ? __seccomp_filter+0x28/0x230 > ? _raw_spin_unlock+0xa/0x20 > ? __handle_mm_fault+0x7d6/0x9b0 > ? list_lru_add+0xa8/0xc0 > ? _raw_spin_unlock+0xa/0x20 > ? __alloc_fd+0xaf/0x160 > ? do_sys_open+0x1a6/0x230 > do_sys_open+0x1a6/0x230 > do_syscall_64+0x5a/0x100 > entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > > Signed-off-by: Jens Axboe <axboe@kernel.dk> Looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > > --- > > diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c > index 0cf25d789d05..3f3cb72e0c0c 100644 > --- a/drivers/scsi/sr.c > +++ b/drivers/scsi/sr.c > @@ -587,18 +587,28 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, > static unsigned int sr_block_check_events(struct gendisk *disk, > unsigned int clearing) > { > - struct scsi_cd *cd = scsi_cd(disk); > + unsigned int ret = 0; > + struct scsi_cd *cd; > > - if (atomic_read(&cd->device->disk_events_disable_depth)) > + cd = scsi_cd_get(disk); > + if (!cd) > return 0; > > - return cdrom_check_events(&cd->cdi, clearing); > + if (!atomic_read(&cd->device->disk_events_disable_depth)) > + ret = cdrom_check_events(&cd->cdi, clearing); > + > + scsi_cd_put(cd); > + return ret; > } > > static int sr_block_revalidate_disk(struct gendisk *disk) > { > - struct scsi_cd *cd = scsi_cd(disk); > struct scsi_sense_hdr sshdr; > + struct scsi_cd *cd; > + > + cd = scsi_cd_get(disk); > + if (!cd) > + return -ENXIO; > > /* if the unit is not ready, nothing more to do */ > if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr)) > @@ -607,6 +617,7 @@ static int sr_block_revalidate_disk(struct gendisk *disk) > sr_cd_check(&cd->cdi); > get_sectorsize(cd); > out: > + scsi_cd_put(cd); > return 0; > } > > > -- > Jens Axboe >
Jens, > We can't just use scsi_cd() to get the scsi_cd structure, we have > to grab a live reference to the device. For both callbacks, we're > not inside an open where we already hold a reference to the device. Applied to 4.17/scsi-fixes, thanks!
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index 0cf25d789d05..3f3cb72e0c0c 100644 --- a/drivers/scsi/sr.c +++ b/drivers/scsi/sr.c @@ -587,18 +587,28 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd, static unsigned int sr_block_check_events(struct gendisk *disk, unsigned int clearing) { - struct scsi_cd *cd = scsi_cd(disk); + unsigned int ret = 0; + struct scsi_cd *cd; - if (atomic_read(&cd->device->disk_events_disable_depth)) + cd = scsi_cd_get(disk); + if (!cd) return 0; - return cdrom_check_events(&cd->cdi, clearing); + if (!atomic_read(&cd->device->disk_events_disable_depth)) + ret = cdrom_check_events(&cd->cdi, clearing); + + scsi_cd_put(cd); + return ret; } static int sr_block_revalidate_disk(struct gendisk *disk) { - struct scsi_cd *cd = scsi_cd(disk); struct scsi_sense_hdr sshdr; + struct scsi_cd *cd; + + cd = scsi_cd_get(disk); + if (!cd) + return -ENXIO; /* if the unit is not ready, nothing more to do */ if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr)) @@ -607,6 +617,7 @@ static int sr_block_revalidate_disk(struct gendisk *disk) sr_cd_check(&cd->cdi); get_sectorsize(cd); out: + scsi_cd_put(cd); return 0; }
We can't just use scsi_cd() to get the scsi_cd structure, we have to grab a live reference to the device. For both callbacks, we're not inside an open where we already hold a reference to the device. This fixes device removal/addition under concurrent device access, which otherwise could result in the below oops. NULL pointer dereference at 0000000000000010 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: sr 12:0:0:0: [sr2] scsi-1 drive scsi_debug crc_t10dif crct10dif_generic crct10dif_common nvme nvme_core sb_edac xl sr 12:0:0:0: Attached scsi CD-ROM sr2 sr_mod cdrom btrfs xor zstd_decompress zstd_compress xxhash lzo_compress zlib_defc sr 12:0:0:0: Attached scsi generic sg7 type 5 igb ahci libahci i2c_algo_bit libata dca [last unloaded: crc_t10dif] CPU: 43 PID: 4629 Comm: systemd-udevd Not tainted 4.16.0+ #650 Hardware name: Dell Inc. PowerEdge T630/0NT78X, BIOS 2.3.4 11/09/2016 RIP: 0010:sr_block_revalidate_disk+0x23/0x190 [sr_mod] RSP: 0018:ffff883ff357bb58 EFLAGS: 00010292 RAX: ffffffffa00b07d0 RBX: ffff883ff3058000 RCX: ffff883ff357bb66 RDX: 0000000000000003 RSI: 0000000000007530 RDI: ffff881fea631000 RBP: 0000000000000000 R08: ffff881fe4d38400 R09: 0000000000000000 R10: 0000000000000000 R11: 00000000000001b6 R12: 000000000800005d R13: 000000000800005d R14: ffff883ffd9b3790 R15: 0000000000000000 FS: 00007f7dc8e6d8c0(0000) GS:ffff883fff340000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 0000003ffda98005 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? __invalidate_device+0x48/0x60 check_disk_change+0x4c/0x60 sr_block_open+0x16/0xd0 [sr_mod] __blkdev_get+0xb9/0x450 ? iget5_locked+0x1c0/0x1e0 blkdev_get+0x11e/0x320 ? bdget+0x11d/0x150 ? _raw_spin_unlock+0xa/0x20 ? bd_acquire+0xc0/0xc0 do_dentry_open+0x1b0/0x320 ? inode_permission+0x24/0xc0 path_openat+0x4e6/0x1420 ? cpumask_any_but+0x1f/0x40 ? flush_tlb_mm_range+0xa0/0x120 do_filp_open+0x8c/0xf0 ? __seccomp_filter+0x28/0x230 ? _raw_spin_unlock+0xa/0x20 ? __handle_mm_fault+0x7d6/0x9b0 ? list_lru_add+0xa8/0xc0 ? _raw_spin_unlock+0xa/0x20 ? __alloc_fd+0xaf/0x160 ? do_sys_open+0x1a6/0x230 do_sys_open+0x1a6/0x230 do_syscall_64+0x5a/0x100 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Signed-off-by: Jens Axboe <axboe@kernel.dk> ---