[1/1] sctp: prevent reading out-of-bounds memory

Submitted by Andrew Morton on Oct. 1, 2010, 9:16 p.m.

Details

Message ID 201010012116.o91LGwS5021150@imap1.linux-foundation.org
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Andrew Morton Oct. 1, 2010, 9:16 p.m.
From: Dan Rosenberg <dan.j.rosenberg@gmail.com>

Two user-controlled allocations in SCTP are subsequently dereferenced as
sockaddr structs, without checking if the dereferenced struct members fall
beyond the end of the allocated chunk.  There doesn't appear to be any
information leakage here based on how these members are used and
additional checking, but it's still worth fixing.

[akpm@linux-foundation.org: remove unfashionable newlines, fix gmail tab->space conversion]
Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 net/sctp/socket.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

Comments

David Miller Oct. 4, 2010, 4:59 a.m.
From: akpm@linux-foundation.org
Date: Fri, 01 Oct 2010 14:16:58 -0700

> From: Dan Rosenberg <dan.j.rosenberg@gmail.com>
> 
> Two user-controlled allocations in SCTP are subsequently dereferenced as
> sockaddr structs, without checking if the dereferenced struct members fall
> beyond the end of the allocated chunk.  There doesn't appear to be any
> information leakage here based on how these members are used and
> additional checking, but it's still worth fixing.
> 
> [akpm@linux-foundation.org: remove unfashionable newlines, fix gmail tab->space conversion]
> Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com>
> Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
> Cc: David Miller <davem@davemloft.net>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Applied.
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diff -puN net/sctp/socket.c~sctp-prevent-reading-out-of-bounds-memory net/sctp/socket.c
--- a/net/sctp/socket.c~sctp-prevent-reading-out-of-bounds-memory
+++ a/net/sctp/socket.c
@@ -918,6 +918,11 @@  SCTP_STATIC int sctp_setsockopt_bindx(st
 	/* Walk through the addrs buffer and count the number of addresses. */
 	addr_buf = kaddrs;
 	while (walk_size < addrs_size) {
+		if (walk_size + sizeof(sa_family_t) > addrs_size) {
+			kfree(kaddrs);
+			return -EINVAL;
+		}
+
 		sa_addr = (struct sockaddr *)addr_buf;
 		af = sctp_get_af_specific(sa_addr->sa_family);
 
@@ -1004,9 +1009,13 @@  static int __sctp_connect(struct sock* s
 	/* Walk through the addrs buffer and count the number of addresses. */
 	addr_buf = kaddrs;
 	while (walk_size < addrs_size) {
+		if (walk_size + sizeof(sa_family_t) > addrs_size) {
+			err = -EINVAL;
+			goto out_free;
+		}
+
 		sa_addr = (union sctp_addr *)addr_buf;
 		af = sctp_get_af_specific(sa_addr->sa.sa_family);
-		port = ntohs(sa_addr->v4.sin_port);
 
 		/* If the address family is not supported or if this address
 		 * causes the address buffer to overflow return EINVAL.
@@ -1016,6 +1025,8 @@  static int __sctp_connect(struct sock* s
 			goto out_free;
 		}
 
+		port = ntohs(sa_addr->v4.sin_port);
+
 		/* Save current address so we can work with it */
 		memcpy(&to, sa_addr, af->sockaddr_len);