diff options
| author | Pavel Shilovsky <pshilovsky@samba.org> | 2016-07-24 09:37:38 +0200 |
|---|---|---|
| committer | Steve French <smfrench@gmail.com> | 2016-07-28 05:55:56 +0200 |
| commit | 7893242e2465aea6f2cbc2639da8fa5ce96e8cc2 (patch) | |
| tree | 1cab64729128945784e3e72ac5796a1671187eb7 /fs/cifs | |
| parent | fs/cifs: make share unaccessible at root level mountable (diff) | |
| download | linux-7893242e2465aea6f2cbc2639da8fa5ce96e8cc2.tar.xz linux-7893242e2465aea6f2cbc2639da8fa5ce96e8cc2.zip | |
CIFS: Fix a possible invalid memory access in smb2_query_symlink()
During following a symbolic link we received err_buf from SMB2_open().
While the validity of SMB2 error response is checked previously
in smb2_check_message() a symbolic link payload is not checked at all.
Fix it by adding such checks.
Cc: Dan Carpenter <dan.carpenter@oracle.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
Diffstat (limited to 'fs/cifs')
| -rw-r--r-- | fs/cifs/smb2ops.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 527d1ac8583b..d203c0329626 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -1044,6 +1044,9 @@ smb2_new_lease_key(struct cifs_fid *fid) get_random_bytes(fid->lease_key, SMB2_LEASE_KEY_SIZE); } +#define SMB2_SYMLINK_STRUCT_SIZE \ + (sizeof(struct smb2_err_rsp) - 1 + sizeof(struct smb2_symlink_err_rsp)) + static int smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon, const char *full_path, char **target_path, @@ -1056,7 +1059,10 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid fid; struct smb2_err_rsp *err_buf = NULL; struct smb2_symlink_err_rsp *symlink; - unsigned int sub_len, sub_offset; + unsigned int sub_len; + unsigned int sub_offset; + unsigned int print_len; + unsigned int print_offset; cifs_dbg(FYI, "%s: path: %s\n", __func__, full_path); @@ -1077,11 +1083,33 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon, kfree(utf16_path); return -ENOENT; } + + if (le32_to_cpu(err_buf->ByteCount) < sizeof(struct smb2_symlink_err_rsp) || + get_rfc1002_length(err_buf) + 4 < SMB2_SYMLINK_STRUCT_SIZE) { + kfree(utf16_path); + return -ENOENT; + } + /* open must fail on symlink - reset rc */ rc = 0; symlink = (struct smb2_symlink_err_rsp *)err_buf->ErrorData; sub_len = le16_to_cpu(symlink->SubstituteNameLength); sub_offset = le16_to_cpu(symlink->SubstituteNameOffset); + print_len = le16_to_cpu(symlink->PrintNameLength); + print_offset = le16_to_cpu(symlink->PrintNameOffset); + + if (get_rfc1002_length(err_buf) + 4 < + SMB2_SYMLINK_STRUCT_SIZE + sub_offset + sub_len) { + kfree(utf16_path); + return -ENOENT; + } + + if (get_rfc1002_length(err_buf) + 4 < + SMB2_SYMLINK_STRUCT_SIZE + print_offset + print_len) { + kfree(utf16_path); + return -ENOENT; + } + *target_path = cifs_strndup_from_utf16( (char *)symlink->PathBuffer + sub_offset, sub_len, true, cifs_sb->local_nls); |