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authorTaehee Yoo <ap420073@gmail.com>2020-02-01 16:43:13 +0000
committerJakub Kicinski <kuba@kernel.org>2020-02-03 15:32:20 -0800
commit8526ad9646b17c59b6d430d8baa8f152a14fe177 (patch)
tree00d8773e6d3f6c538805e6b92ee4fb2924d27ab1 /drivers/net/netdevsim
parent6ab63366e1ec4ec1900f253aa64727b4b5f4ee73 (diff)
netdevsim: fix panic in nsim_dev_take_snapshot_write()
nsim_dev_take_snapshot_write() uses nsim_dev and nsim_dev->dummy_region. So, during this function, these data shouldn't be removed. But there is no protecting stuff in this function. There are two similar cases. 1. reload case reload could be called during nsim_dev_take_snapshot_write(). When reload is being executed, nsim_dev_reload_down() is called and it calls nsim_dev_reload_destroy(). nsim_dev_reload_destroy() calls devlink_region_destroy() to destroy nsim_dev->dummy_region. So, during nsim_dev_take_snapshot_write(), nsim_dev->dummy_region() would be removed. At this point, snapshot_write() would access freed pointer. In order to fix this case, take_snapshot file will be removed before devlink_region_destroy(). The take_snapshot file will be re-created by ->reload_up(). 2. del_device_store case del_device_store() also could call nsim_dev_reload_destroy() during nsim_dev_take_snapshot_write(). If so, panic would occur. This problem is actually the same problem with the first case. So, this problem will be fixed by the first case's solution. Test commands: modprobe netdevsim while : do echo 1 > /sys/bus/netdevsim/new_device & echo 1 > /sys/bus/netdevsim/del_device & devlink dev reload netdevsim/netdevsim1 & echo 1 > /sys/kernel/debug/netdevsim/netdevsim1/take_snapshot & done Splat looks like: [ 45.564513][ T975] general protection fault, probably for non-canonical address 0xdffffc000000003a: 0000 [#1] SMP DEI [ 45.566131][ T975] KASAN: null-ptr-deref in range [0x00000000000001d0-0x00000000000001d7] [ 45.566135][ T975] CPU: 1 PID: 975 Comm: bash Not tainted 5.5.0+ #322 [ 45.569020][ T975] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 45.569026][ T975] RIP: 0010:__mutex_lock+0x10a/0x14b0 [ 45.570518][ T975] Code: 08 84 d2 0f 85 7f 12 00 00 44 8b 0d 10 23 65 02 45 85 c9 75 29 49 8d 7f 68 48 b8 00 00 00 0f [ 45.570522][ T975] RSP: 0018:ffff888046ccfbf0 EFLAGS: 00010206 [ 45.572305][ T975] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 45.572308][ T975] RDX: 000000000000003a RSI: ffffffffac926440 RDI: 00000000000001d0 [ 45.576843][ T975] RBP: ffff888046ccfd70 R08: ffffffffab610645 R09: 0000000000000000 [ 45.576847][ T975] R10: ffff888046ccfd90 R11: ffffed100d6360ad R12: 0000000000000000 [ 45.578471][ T975] R13: dffffc0000000000 R14: ffffffffae1976c0 R15: 0000000000000168 [ 45.578475][ T975] FS: 00007f614d6e7740(0000) GS:ffff88806c400000(0000) knlGS:0000000000000000 [ 45.581492][ T975] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 45.582942][ T975] CR2: 00005618677d1cf0 CR3: 000000005fb9c002 CR4: 00000000000606e0 [ 45.584543][ T975] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 45.586633][ T975] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 45.589889][ T975] Call Trace: [ 45.591445][ T975] ? devlink_region_snapshot_create+0x55/0x4a0 [ 45.601250][ T975] ? mutex_lock_io_nested+0x1380/0x1380 [ 45.602817][ T975] ? mutex_lock_io_nested+0x1380/0x1380 [ 45.603875][ T975] ? mark_held_locks+0xa5/0xe0 [ 45.604769][ T975] ? _raw_spin_unlock_irqrestore+0x2d/0x50 [ 45.606147][ T975] ? __mutex_unlock_slowpath+0xd0/0x670 [ 45.607723][ T975] ? crng_backtrack_protect+0x80/0x80 [ 45.613530][ T975] ? wait_for_completion+0x390/0x390 [ 45.615152][ T975] ? devlink_region_snapshot_create+0x55/0x4a0 [ 45.616834][ T975] devlink_region_snapshot_create+0x55/0x4a0 [ ... ] Fixes: 4418f862d675 ("netdevsim: implement support for devlink region and snapshots") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers/net/netdevsim')
-rw-r--r--drivers/net/netdevsim/dev.c13
-rw-r--r--drivers/net/netdevsim/netdevsim.h1
2 files changed, 12 insertions, 2 deletions
diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index b53fbc06e104..06b178be3017 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -88,8 +88,11 @@ static int nsim_dev_debugfs_init(struct nsim_dev *nsim_dev)
&nsim_dev->max_macs);
debugfs_create_bool("test1", 0600, nsim_dev->ddir,
&nsim_dev->test1);
- debugfs_create_file("take_snapshot", 0200, nsim_dev->ddir, nsim_dev,
- &nsim_dev_take_snapshot_fops);
+ nsim_dev->take_snapshot = debugfs_create_file("take_snapshot",
+ 0200,
+ nsim_dev->ddir,
+ nsim_dev,
+ &nsim_dev_take_snapshot_fops);
debugfs_create_bool("dont_allow_reload", 0600, nsim_dev->ddir,
&nsim_dev->dont_allow_reload);
debugfs_create_bool("fail_reload", 0600, nsim_dev->ddir,
@@ -740,6 +743,11 @@ static int nsim_dev_reload_create(struct nsim_dev *nsim_dev,
if (err)
goto err_health_exit;
+ nsim_dev->take_snapshot = debugfs_create_file("take_snapshot",
+ 0200,
+ nsim_dev->ddir,
+ nsim_dev,
+ &nsim_dev_take_snapshot_fops);
return 0;
err_health_exit:
@@ -853,6 +861,7 @@ static void nsim_dev_reload_destroy(struct nsim_dev *nsim_dev)
if (devlink_is_reload_failed(devlink))
return;
+ debugfs_remove(nsim_dev->take_snapshot);
nsim_dev_port_del_all(nsim_dev);
nsim_dev_health_exit(nsim_dev);
nsim_dev_traps_exit(devlink);
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index be100b11a055..2eb7b0dc1594 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -160,6 +160,7 @@ struct nsim_dev {
struct nsim_trap_data *trap_data;
struct dentry *ddir;
struct dentry *ports_ddir;
+ struct dentry *take_snapshot;
struct bpf_offload_dev *bpf_dev;
bool bpf_bind_accept;
u32 bpf_bind_verifier_delay;