Hi Mateusz, On Wed, May 24, 2017 at 12:26:20PM +0200, Mateusz Jurczyk wrote: > Fix the sockaddr length verification in the connect() handler of NFC/LLCP > sockets, to compare against the size of the actual structure expected on > input (sockaddr_nfc_llcp) instead of its shorter version (sockaddr_nfc). > > Both structures are defined in include/uapi/linux/nfc.h. The fields > specific to the _llcp extended struct are as follows: > > 276 __u8 dsap; /* Destination SAP, if known */ > 277 __u8 ssap; /* Source SAP to be bound to */ > 278 char service_name[NFC_LLCP_MAX_SERVICE_NAME]; /* Service name URI */; > 279 size_t service_name_len; > > If the caller doesn't provide a sufficiently long sockaddr buffer, these > fields remain uninitialized (and they currently originate from the stack > frame of the top-level sys_connect handler). They are then copied by > llcp_sock_connect() into internal storage (nfc_llcp_sock structure), and > could be subsequently read back through the user-mode getsockname() > function (handled by llcp_sock_getname()). This would result in the > disclosure of up to ~70 uninitialized bytes from the kernel stack to > user-mode clients capable of creating AFC_NFC sockets. > > Signed-off-by: Mateusz Jurczyk <mjurczyk@xxxxxxxxxx> > --- > net/nfc/llcp_sock.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) Applied to nfc-next, thanks. Cheers, Samuel.
