diff options
| -rw-r--r-- | fs/cifs/smb2ops.c | 34 |
1 files changed, 27 insertions, 7 deletions
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 812e4884c392..68622f1e706b 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -894,6 +894,13 @@ smb3_set_integrity(const unsigned int xid, struct cifs_tcon *tcon, } +/* GMT Token is @GMT-YYYY.MM.DD-HH.MM.SS Unicode which is 48 bytes + null */ +#define GMT_TOKEN_SIZE 50 + +/* + * Input buffer contains (empty) struct smb_snapshot array with size filled in + * For output see struct SRV_SNAPSHOT_ARRAY in MS-SMB2 section 2.2.32.2 + */ static int smb3_enum_snapshots(const unsigned int xid, struct cifs_tcon *tcon, struct cifsFileInfo *cfile, void __user *ioc_buf) @@ -922,14 +929,27 @@ smb3_enum_snapshots(const unsigned int xid, struct cifs_tcon *tcon, kfree(retbuf); return rc; } - if (snapshot_in.snapshot_array_size < sizeof(struct smb_snapshot_array)) { - rc = -ERANGE; - kfree(retbuf); - return rc; - } - if (ret_data_len > snapshot_in.snapshot_array_size) - ret_data_len = snapshot_in.snapshot_array_size; + /* + * Check for min size, ie not large enough to fit even one GMT + * token (snapshot). On the first ioctl some users may pass in + * smaller size (or zero) to simply get the size of the array + * so the user space caller can allocate sufficient memory + * and retry the ioctl again with larger array size sufficient + * to hold all of the snapshot GMT tokens on the second try. + */ + if (snapshot_in.snapshot_array_size < GMT_TOKEN_SIZE) + ret_data_len = sizeof(struct smb_snapshot_array); + + /* + * We return struct SRV_SNAPSHOT_ARRAY, followed by + * the snapshot array (of 50 byte GMT tokens) each + * representing an available previous version of the data + */ + if (ret_data_len > (snapshot_in.snapshot_array_size + + sizeof(struct smb_snapshot_array))) + ret_data_len = snapshot_in.snapshot_array_size + + sizeof(struct smb_snapshot_array); if (copy_to_user(ioc_buf, retbuf, ret_data_len)) rc = -EFAULT; |