[ Upstream commit 79ebe9110fa458d58f1fceb078e2068d7ad37390 ]
Open /dev/nbdX first, the config_refs will be 1 and
the pointers in nbd_device are still null. Disconnect
/dev/nbdX, then reference a null recv_workq. The
protection by config_refs in nbd_genl_disconnect is useless.
[ 656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020
[ 656.368943] #PF: supervisor write access in kernel mode
[ 656.369844] #PF: error_code(0x0002) - not-present page
[ 656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0
[ 656.371693] Oops: 0002 [#1] SMP
[ 656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1
[ 656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
[ 656.375904] RIP: 0010:mutex_lock+0x29/0x60
[ 656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 <f0> 48 0f b1 55 d
[ 656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246
[ 656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020
[ 656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318
[ 656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40
[ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00
[ 656.382166] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000
[ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0
[ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 656.384927] Call Trace:
[ 656.385111] flush_workqueue+0x92/0x6c0
[ 656.385395] nbd_disconnect_and_put+0x81/0xd0
[ 656.385716] nbd_genl_disconnect+0x125/0x2a0
[ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0
[ 656.386422] genl_rcv_msg+0xfc/0x2b0
[ 656.386685] ? nbd_ioctl+0x490/0x490
[ 656.386954] ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0
[ 656.387354] netlink_rcv_skb+0x62/0x180
[ 656.387638] genl_rcv+0x34/0x60
[ 656.387874] netlink_unicast+0x26d/0x590
[ 656.388162] netlink_sendmsg+0x398/0x6c0
[ 656.388451] ? netlink_rcv_skb+0x180/0x180
[ 656.388750] ____sys_sendmsg+0x1da/0x320
[ 656.389038] ? ____sys_recvmsg+0x130/0x220
[ 656.389334] ___sys_sendmsg+0x8e/0xf0
[ 656.389605] ? ___sys_recvmsg+0xa2/0xf0
[ 656.389889] ? handle_mm_fault+0x1671/0x21d0
[ 656.390201] __sys_sendmsg+0x6d/0xe0
[ 656.390464] __x64_sys_sendmsg+0x23/0x30
[ 656.390751] do_syscall_64+0x45/0x70
[ 656.391017] entry_SYSCALL_64_after_hwframe+0x44/0xa9
To fix it, just add if (nbd->recv_workq) to nbd_disconnect_and_put().
Fixes: e9e006f5fcf2 ("nbd: fix max number of supported devs")
Signed-off-by: Sun Ke <sunke32@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20210512114331.1233964-2-sunke32@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit c9a2f90f4d6b9d42b9912f7aaf68e8d748acfffd upstream.
There exists a race where we can be attempting to create a new nbd
configuration while a previous configuration is going down, both
configured with DESTROY_ON_DISCONNECT. Normally devices all have a
reference of 1, as they won't be cleaned up until the module is torn
down. However with DESTROY_ON_DISCONNECT we'll make sure that there is
only 1 reference (generally) on the device for the config itself, and
then once the config is dropped, the device is torn down.
The race that exists looks like this
TASK1 TASK2
nbd_genl_connect()
idr_find()
refcount_inc_not_zero(nbd)
* count is 2 here ^^
nbd_config_put()
nbd_put(nbd) (count is 1)
setup new config
check DESTROY_ON_DISCONNECT
put_dev = true
if (put_dev) nbd_put(nbd)
* free'd here ^^
In nbd_genl_connect() we assume that the nbd ref count will be 2,
however clearly that won't be true if the nbd device had been setup as
DESTROY_ON_DISCONNECT with its prior configuration. Fix this by getting
rid of the runtime flag to check if we need to mess with the nbd device
refcount, and use the device NBD_DESTROY_ON_DISCONNECT flag to check if
we need to adjust the ref counts. This was reported by syzkaller with
the following kasan dump
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in refcount_dec_not_one+0x71/0x1e0 lib/refcount.c:76
Read of size 4 at addr ffff888143bf71a0 by task systemd-udevd/8451
CPU: 0 PID: 8451 Comm: systemd-udevd Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:230
__kasan_report mm/kasan/report.c:396 [inline]
kasan_report.cold+0x79/0xd5 mm/kasan/report.c:413
check_memory_region_inline mm/kasan/generic.c:179 [inline]
check_memory_region+0x13d/0x180 mm/kasan/generic.c:185
instrument_atomic_read include/linux/instrumented.h:71 [inline]
atomic_read include/asm-generic/atomic-instrumented.h:27 [inline]
refcount_dec_not_one+0x71/0x1e0 lib/refcount.c:76
refcount_dec_and_mutex_lock+0x19/0x140 lib/refcount.c:115
nbd_put drivers/block/nbd.c:248 [inline]
nbd_release+0x116/0x190 drivers/block/nbd.c:1508
__blkdev_put+0x548/0x800 fs/block_dev.c:1579
blkdev_put+0x92/0x570 fs/block_dev.c:1632
blkdev_close+0x8c/0xb0 fs/block_dev.c:1640
__fput+0x283/0x920 fs/file_table.c:280
task_work_run+0xdd/0x190 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fc1e92b5270
Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24
RSP: 002b:00007ffe8beb2d18 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fc1e92b5270
RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 00007fc1ea16f710 R08: 000000000000004a R09: 0000000000000008
R10: 0000562f8cb0b2a8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000562f8cb0afd0 R14: 0000000000000003 R15: 000000000000000e
Allocated by task 1:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:401 [inline]
____kasan_kmalloc.constprop.0+0x82/0xa0 mm/kasan/common.c:429
kmalloc include/linux/slab.h:552 [inline]
kzalloc include/linux/slab.h:682 [inline]
nbd_dev_add+0x44/0x8e0 drivers/block/nbd.c:1673
nbd_init+0x250/0x271 drivers/block/nbd.c:2394
do_one_initcall+0x103/0x650 init/main.c:1223
do_initcall_level init/main.c:1296 [inline]
do_initcalls init/main.c:1312 [inline]
do_basic_setup init/main.c:1332 [inline]
kernel_init_freeable+0x605/0x689 init/main.c:1533
kernel_init+0xd/0x1b8 init/main.c:1421
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Freed by task 8451:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:356
____kasan_slab_free+0xe1/0x110 mm/kasan/common.c:362
kasan_slab_free include/linux/kasan.h:192 [inline]
slab_free_hook mm/slub.c:1547 [inline]
slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1580
slab_free mm/slub.c:3143 [inline]
kfree+0xdb/0x3b0 mm/slub.c:4139
nbd_dev_remove drivers/block/nbd.c:243 [inline]
nbd_put.part.0+0x180/0x1d0 drivers/block/nbd.c:251
nbd_put drivers/block/nbd.c:295 [inline]
nbd_config_put+0x6dd/0x8c0 drivers/block/nbd.c:1242
nbd_release+0x103/0x190 drivers/block/nbd.c:1507
__blkdev_put+0x548/0x800 fs/block_dev.c:1579
blkdev_put+0x92/0x570 fs/block_dev.c:1632
blkdev_close+0x8c/0xb0 fs/block_dev.c:1640
__fput+0x283/0x920 fs/file_table.c:280
task_work_run+0xdd/0x190 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The buggy address belongs to the object at ffff888143bf7000
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 416 bytes inside of
1024-byte region [ffff888143bf7000, ffff888143bf7400)
The buggy address belongs to the page:
page:000000005238f4ce refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x143bf0
head:000000005238f4ce order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head)
raw: 057ff00000010200 ffffea00004b1400 0000000300000003 ffff888010c41140
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888143bf7080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888143bf7100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888143bf7180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888143bf7200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
Reported-and-tested-by: syzbot+429d3f82d757c211bff3@syzkaller.appspotmail.com
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When setting up a device, we can krealloc the config->socks array to add new sockets to the configuration. However if we happen to get a IO request in at this point even though we aren't setup we could hit a UAF, as we deref config->socks without any locking, assuming that the configuration was setup already and that ->socks is safe to access it as we have a reference on the configuration. But there's nothing really preventing IO from occurring at this point of the device setup, we don't want to incur the overhead of a lock to access ->socks when it will never change while the device is running. To fix this UAF scenario simply freeze the queue if we are adding sockets. This will protect us from this particular case without adding any additional overhead for the normal running case. Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
The creation path of the NBD device respects max_part and only scans for partitions if max_part is not 0. However, some other code paths ignore max_part, and unconditionally scan for partitions. Add a check for max_part on each partition scan. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
We can just dereference the point in struct gendisk instead. Also remove the now unused export. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now that the hd_struct always has a block device attached to it, there is no need for having two size field that just get out of sync. Additionally the field in hd_struct did not use proper serialization, possibly allowing for torn writes. By only using the block_device field this problem also gets fixed. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Hannes Reinecke <hare@suse.de> Acked-by: Coly Li <colyli@suse.de> [bcache] Acked-by: Chao Yu <yuchao0@huawei.com> [f2fs] Signed-off-by: Jens Axboe <axboe@kernel.dk>
Use set_capacity_and_notify to update the disk and block device sizes and send a RESIZE uevent to userspace. Note that blktests relies on uevents being sent also for updates that did not change the device size, so the explicit kobject_uevent remains for that case. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move the validation of the block from the callers into nbd_set_size. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Merge nbd_size_set and nbd_size_update into a single function that also updates the nbd_config fields. This new function takes the device size in bytes as the first argument, and the blocksize as the second argument, simplifying the calculations required in most callers. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
nbd_size_update is about to acquire a few more callers, so lift the check into the function. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>