Re: [PATCH] nfc: Add sockaddr length checks before accessing sa_family in bind handlers

[Samuel Ortiz]

On Tue, Jun 13, 2017 at 06:44:28PM +0200, Mateusz Jurczyk wrote:
> Verify that the caller-provided sockaddr structure is large enough to
> contain the sa_family field, before accessing it in bind() handlers of the
> AF_NFC socket. Since the syscall doesn't enforce a minimum size of the
> corresponding memory region, very short sockaddrs (zero or one byte long)
> result in operating on uninitialized memory while referencing .sa_family.
> 
> Signed-off-by: Mateusz Jurczyk 
> ---
>  net/nfc/llcp_sock.c | 6 --
>  1 file changed, 4 insertions(+), 2 deletions(-)
Applied to nfc-next, thanks.

Cheers,
Samuel.

[PATCH] nfc: Add sockaddr length checks before accessing sa_family in bind handlers

[Mateusz Jurczyk]

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in bind() handlers of the
AF_NFC socket. Since the syscall doesn't enforce a minimum size of the
corresponding memory region, very short sockaddrs (zero or one byte long)
result in operating on uninitialized memory while referencing .sa_family.

Signed-off-by: Mateusz Jurczyk 
---
 net/nfc/llcp_sock.c | 6 --
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 2ffb18e73df6..80cf35ed320a 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -77,7 +77,8 @@ static int llcp_sock_bind(struct socket *sock, struct 
sockaddr *addr, int alen)
struct sockaddr_nfc_llcp llcp_addr;
int len, ret = 0;
 
-   if (!addr || addr->sa_family != AF_NFC)
+   if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
+   addr->sa_family != AF_NFC)
return -EINVAL;
 
pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);
@@ -151,7 +152,8 @@ static int llcp_raw_sock_bind(struct socket *sock, struct 
sockaddr *addr,
struct sockaddr_nfc_llcp llcp_addr;
int len, ret = 0;
 
-   if (!addr || addr->sa_family != AF_NFC)
+   if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
+   addr->sa_family != AF_NFC)
return -EINVAL;
 
pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);
-- 
2.13.1.508.gb3defc5cc-goog