CVE-2012-6704 (published 2016-12-28T07:59Z)

The sock_setsockopt function in net/core/sock.c in the Linux kernel before 3.5 mishandles negative values of sk_sndbuf and sk_rcvbuf, which allows local users to cause a denial of service (memory corruption and system crash) or possibly have unspecified other impact by leveraging the CAP_NET_ADMIN capability for a crafted setsockopt system call with the (1) SO_SNDBUF or (2) SO_RCVBUF option.

Severity: HIGH
CVSS v2 base score: 7.2 (AV:L/AC:L/Au:N/C:C/I:C/A:C)
CVSS v3 base score: 7.8, HIGH (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-119
cwe_name: Improper Restriction of Operations within the Bounds of a Memory Buffer
description: The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
extended_description: 
            Certain languages allow direct addressing of memory locations and do not automatically ensure that these locations are valid for the memory buffer that is being referenced. This can cause read or write operations to be performed on memory locations that may be associated with other variables, data structures, or internal program data.
         
         

Fix information:
repo_url: https://github.com/torvalds/linux
commit_details: repo_url: https://github.com/torvalds/linux
author: Eric Dumazet
author_date: 2012-04-26 20:07:59+00:00
msg: net: cleanups in sock_setsockopt()

Use min_t()/max_t() macros, reformat two comments, use !!test_bit() to
match !!sock_flag()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
repository: repo_url: https://github.com/torvalds/linux
repo_name: torvalds/linux
description: Linux kernel source tree
repo_language: C
owner: torvalds
file_changes: filename: sock.c
change_type: ModificationType.MODIFY
diff: @@ -577,23 +577,15 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 		break;
 	case SO_SNDBUF:
 		/* Don't error on this BSD doesn't and if you think
-		   about it this is right. Otherwise apps have to
-		   play 'guess the biggest size' games. RCVBUF/SNDBUF
-		   are treated in BSD as hints */
-
-		if (val > sysctl_wmem_max)
-			val = sysctl_wmem_max;
+		 * about it this is right. Otherwise apps have to
+		 * play 'guess the biggest size' games. RCVBUF/SNDBUF
+		 * are treated in BSD as hints
+		 */
+		val = min_t(u32, val, sysctl_wmem_max);
 set_sndbuf:
 		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
-		if ((val * 2) < SOCK_MIN_SNDBUF)
-			sk->sk_sndbuf = SOCK_MIN_SNDBUF;
-		else
-			sk->sk_sndbuf = val * 2;
-
-		/*
-		 *	Wake up sending tasks if we
-		 *	upped the value.
-		 */
+		sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
+		/* Wake up sending tasks if we upped the value. */
 		sk->sk_write_space(sk);
 		break;
 
@@ -606,12 +598,11 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 
 	case SO_RCVBUF:
 		/* Don't error on this BSD doesn't and if you think
-		   about it this is right. Otherwise apps have to
-		   play 'guess the biggest size' games. RCVBUF/SNDBUF
-		   are treated in BSD as hints */
-
-		if (val > sysctl_rmem_max)
-			val = sysctl_rmem_max;
+		 * about it this is right. Otherwise apps have to
+		 * play 'guess the biggest size' games. RCVBUF/SNDBUF
+		 * are treated in BSD as hints
+		 */
+		val = min_t(u32, val, sysctl_rmem_max);
 set_rcvbuf:
 		sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
 		/*
@@ -629,10 +620,7 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 		 * returning the value we actually used in getsockopt
 		 * is the most desirable behavior.
 		 */
-		if ((val * 2) < SOCK_MIN_RCVBUF)
-			sk->sk_rcvbuf = SOCK_MIN_RCVBUF;
-		else
-			sk->sk_rcvbuf = val * 2;
+		sk->sk_rcvbuf = max_t(u32, val * 2, SOCK_MIN_RCVBUF);
 		break;
 
 	case SO_RCVBUFFORCE:
@@ -975,7 +963,7 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case SO_PASSCRED:
-		v.val = test_bit(SOCK_PASSCRED, &sock->flags) ? 1 : 0;
+		v.val = !!test_bit(SOCK_PASSCRED, &sock->flags);
 		break;
 
 	case SO_PEERCRED:
@@ -1010,7 +998,7 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case SO_PASSSEC:
-		v.val = test_bit(SOCK_PASSSEC, &sock->flags) ? 1 : 0;
+		v.val = !!test_bit(SOCK_PASSSEC, &sock->flags);
 		break;
 
 	case SO_PEERSEC:

programming_language: C