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| author |   Mateusz Jurczyk <mjurczyk@google.com> | 2017-05-24 12:26:20 +0200 |
|---|---|---|
| committer |   Samuel Ortiz <sameo@linux.intel.com> | 2017-06-23 00:26:19 +0200 |
| commit | 608c4adfcabab220142ee335a2a003ccd1c0b25b (patch) | |
| tree | 02926d53fd24c2cd655fddd70b324e9446cb1430 /net | |
| parent | Revert "NFC: trf7970a: Handle extra byte in response to Type 5 RMB commands" (diff) | |
| download | linux-dev-608c4adfcabab220142ee335a2a003ccd1c0b25b.tar.xz linux-dev-608c4adfcabab220142ee335a2a003ccd1c0b25b.zip | |
nfc: Fix the sockaddr length sanitization in llcp_sock_connect
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@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/nfc/llcp_sock.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c index 2ffb18e73df6..d0d12bea65cb 100644 --- a/net/nfc/llcp_sock.c +++ b/net/nfc/llcp_sock.c @@ -662,8 +662,7 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr, pr_debug("sock %p sk %p flags 0x%x\n", sock, sk, flags); - if (!addr || len < sizeof(struct sockaddr_nfc) || - addr->sa_family != AF_NFC) + if (!addr || len < sizeof(*addr) || addr->sa_family != AF_NFC) return -EINVAL; if (addr->service_name_len == 0 && addr->dsap == 0) |