2021-10-02 3:51 GMT+09:00, Marios Makassikis <mmakassikis@xxxxxxxxxx>:
> On Mon, 2021-08-23 at 17:13 +0200, Christian Brauner wrote:
>> From: Christian Brauner <christian.brauner@xxxxxxxxxx>
>>
>> Permission checking and copying over ownership information is the
>> task
>> of the underlying filesystem not ksmbd. The order is also wrong here.
>> This modifies the inode before notify_change(). If notify_change()
>> fails
>> this will have changed ownership nonetheless. All of this is
>> unnecessary
>> though since the underlying filesystem's ->setattr handler will do
>> all
>> this (if required) by itself.
>> Cc: Steve French <stfrench@xxxxxxxxxxxxx>
>> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
>> Cc: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
>> Cc: Hyunchul Lee <hyc.lee@xxxxxxxxx>
>> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
>> Cc: linux-cifs@xxxxxxxxxxxxxxx
>> Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
>> ---
>> fs/ksmbd/smb2pdu.c | 5 -----
>> 1 file changed, 5 deletions(-)
>>
>> diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
>> index 1148e52a4037..059764753aaa 100644
>> --- a/fs/ksmbd/smb2pdu.c
>> +++ b/fs/ksmbd/smb2pdu.c
>> @@ -5521,12 +5521,7 @@ static int set_file_basic_info(struct
>> ksmbd_file *fp, char *buf,
>> if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
>> return -EACCES;
>>
>> - rc = setattr_prepare(user_ns, dentry, &attrs);
>> - if (rc)
>> - return -EINVAL;
>> -
>> inode_lock(inode);
>> - setattr_copy(user_ns, inode, &attrs);
>> attrs.ia_valid &= ~ATTR_CTIME;
>> rc = notify_change(user_ns, dentry, &attrs, NULL);
>> inode_unlock(inode);
>
> Hello,
Hi Marios,
>
> With this change, rsync'ing a large directory (kernel repo checkout for
> example) to a FUSE-backed share crashes the kernel:
>
> BUG: unable to handle page fault for address: fffffffffffffff8
> #PF: supervisor write access in kernel mode
> #PF: error_code(0x0002) - not-present page
> PGD 3229067 P4D 3229067 PUD 322b067 PMD 0
> Oops: 0002 [#1] SMP KASAN NOPTI
> CPU: 0 PID: 55 Comm: kworker/u2:1 Not tainted 5.15.0-rc3+ #186
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-
> 1ubuntu1.1 04/01/2014
> Workqueue: writeback wb_workfn (flush-8:17-fuseblk)
> RIP: 0010:fuse_file_get+0x26/0x50
> Code: 00 0f 1f 00 0f 1f 44 00 00 41 56 53 48 89 fb 4c 8d 77 28 4c 89
> f7 be 04 00 00 00 e8 54 ad c1 ff be 01 00 00 00 b8 01 00 e
> RSP: 0018:ffffc900001af660 EFLAGS: 00010256
> RAX: 0000000000000001 RBX: ffffffffffffffd0 RCX: ffffffff818314cc
> RDX: 0000000000000001 RSI: 0000000000000001 RDI: fffffffffffffff8
> RBP: ffff8880108b0680 R08: dffffc0000000000 R09: fffffc0000000000
> R10: fffffc0000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000020087 R14: fffffffffffffff8 R15: ffff8880108b0680
> FS: 0000000000000000(0000) GS:ffff888036200000(0000)
> knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: fffffffffffffff8 CR3: 00000000101a4000 CR4: 00000000000006f0
> Call Trace:
> __fuse_write_file_get+0x4e/0x70
> fuse_write_inode+0xf/0x40
> __writeback_single_inode+0x206/0x250
> writeback_sb_inodes+0x3fb/0x760
> ? queue_io+0xd0/0xd0
> ? trylock_super+0x17/0x60
> ? __init_rwsem+0xf0/0xf0
> ? rcu_read_lock_sched_held+0xa5/0x130
> ? __bpf_trace_rcu_barrier+0x10/0x10
> ? do_raw_spin_lock+0x14f/0x250
> ? __bpf_trace_rcu_barrier+0x10/0x10
> __writeback_inodes_wb+0xbf/0x130
> wb_writeback+0x25b/0x360
> ? print_irqtrace_events+0x110/0x110
> ? trace_writeback_exec+0x150/0x150
> ? _local_bh_enable+0x70/0x70
> ? cpumask_next+0x20/0x50
> ? cpumask_next+0x20/0x50
> wb_workfn+0x608/0x860
> ? __inode_wait_for_writeback+0x1c0/0x1c0
> ? check_chain_key+0x1cf/0x2a0
> ? __lock_acquire+0x9f4/0xdf0
> ? lock_acquire+0x14d/0x370
> ? process_one_work+0x2c5/0x550
> ? lock_acquire+0x176/0x370
> ? rcu_read_lock_sched_held+0xa5/0x130
> ? __bpf_trace_rcu_barrier+0x10/0x10
> ? lock_acquire+0x14d/0x370
> ? worker_thread+0xf8/0x4a0
> ? lock_acquire+0x176/0x370
> process_one_work+0x304/0x550
> ? worker_detach_from_pool+0x100/0x100
> ? _raw_spin_lock_irq+0xaf/0xe0
> ? _raw_spin_lock_irqsave+0xf0/0xf0
> ? __list_add_valid+0x2a/0xa0
> worker_thread+0x373/0x4a0
> kthread+0x1d9/0x1f0
> ? pr_cont_work+0xa0/0xa0
> ? __list_add+0x50/0x50
> ret_from_fork+0x1f/0x30
> Modules linked in:
> CR2: fffffffffffffff8
> ---[ end trace fa4a96caf17482dd ]---
>
> $ ./scripts/faddr2line vmlinux.o fuse_file_get+0x26/0x50
> fuse_file_get+0x26/0x50:
> arch_atomic_fetch_add at arch/x86/include/asm/atomic.h:184
> (inlined by) atomic_fetch_add_relaxed at include/asm-generic/atomic-
> instrumented.h:143
> (inlined by) __refcount_add at include/linux/refcount.h:193
> (inlined by) __refcount_inc at include/linux/refcount.h:250
> (inlined by) refcount_inc at include/linux/refcount.h:267
> (inlined by) fuse_file_get at fs/fuse/file.c:93
>
> $ ./scripts/faddr2line vmlinux.o __fuse_write_file_get+0x4e/0x70
> __fuse_write_file_get+0x4e/0x70:
> __fuse_write_file_get at fs/fuse/file.c:1827
>
> I had already encountered this before [0]. Back then, changing ksmbd to
> use notify_change rather than mark_inode_dirty fixed the issue [1].
>
> Using ext4/xfs does not trigger the bug.
Thanks for your report and detailed check.
>
> rsync'ing the same folder over SMB (with samba4), or over NFS does not
> trigger the bug either. The only combination where I'm seeing this so
> far is ksmbd+FUSE, although I can't tell if it's a bug in ksmbd side or
> FUSE.
Could you please check your issue is fixed with the following change ?
diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 4d1be224dd8e..e58a5a99d6ed 100644
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -5483,7 +5483,6 @@ static int set_file_basic_info(struct ksmbd_file *fp,
struct ksmbd_share_config *share)
{
struct iattr attrs;
- struct timespec64 ctime;
struct file *filp;
struct inode *inode;
struct user_namespace *user_ns;
@@ -5505,13 +5504,11 @@ static int set_file_basic_info(struct ksmbd_file *fp,
attrs.ia_valid |= (ATTR_ATIME | ATTR_ATIME_SET);
}
+ attrs.ia_valid |= ATTR_CTIME;
if (file_info->ChangeTime) {
attrs.ia_ctime = ksmbd_NTtimeToUnix(file_info->ChangeTime);
- ctime = attrs.ia_ctime;
- attrs.ia_valid |= ATTR_CTIME;
- } else {
- ctime = inode->i_ctime;
- }
+ } else
+ attrs.ia_ctime = inode->i_ctime;
if (file_info->LastWriteTime) {
attrs.ia_mtime = ksmbd_NTtimeToUnix(file_info->LastWriteTime);
@@ -5557,11 +5554,9 @@ static int set_file_basic_info(struct ksmbd_file *fp,
return -EACCES;
inode_lock(inode);
+ inode->i_ctime = attrs.ia_ctime;
+ attrs.ia_valid &= ~ATTR_CTIME;
rc = notify_change(user_ns, dentry, &attrs, NULL);
- if (!rc) {
- inode->i_ctime = ctime;
- mark_inode_dirty(inode);
- }
inode_unlock(inode);
}
return rc;
--
2.25.1
>
> Marios
>
> [0]
> https://lore.kernel.org/linux-fsdevel/CAF6XXKWCwqSa72p+iQjg4QSBmAkX4Y5DxGrRR1tW1ar2uthd=w@xxxxxxxxxxxxxx/T/#u
> [1]
> https://github.com/cifsd-team/ksmbd/commit/5e929125e519acaf48abc4c42f8389caa26c4d5a#diff-9f95c7d87d27c50e4e1d0afb24772b60bfa1449d619c118f23d7a2493d3ea9b0
>
>
