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sctp: use memdup_user instead of vmemdup_user 

In sctp_setsockopt_bindx()/__sctp_setsockopt_connectx(), it allocates
memory with addrs_size which is passed from userspace. We used flag
GFP_USER to put some more restrictions on it in Commit cacc062152
("sctp: use GFP_USER for user-controlled kmalloc").

However, since Commit c981f254cc ("sctp: use vmemdup_user() rather
than badly open-coding memdup_user()"), vmemdup_user() has been used,
which doesn't check GFP_USER flag when goes to vmalloc_*(). So when
addrs_size is a huge value, it could exhaust memory and even trigger
oom killer.

This patch is to use memdup_user() instead, in which GFP_USER would
work to limit the memory allocation with a huge addrs_size.

Note we can't fix it by limiting 'addrs_size', as there's no demand
for it from RFC.

Reported-by: syzbot+ec1b7575afef85a0e5ca@syzkaller.appspotmail.com
Fixes: c981f254cc ("sctp: use vmemdup_user() rather than badly open-coding memdup_user()")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2019-03-20 14:49:38 +08:00 committed by David S. Miller
parent 1c87e79a00
commit ef82bcfa67
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/sctp/socket.c
View File

@ -999,7 +999,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
if (unlikely(addrs_size <= 0))
return -EINVAL;
kaddrs = vmemdup_user(addrs, addrs_size);
kaddrs = memdup_user(addrs, addrs_size);
if (unlikely(IS_ERR(kaddrs)))
return PTR_ERR(kaddrs);
@ -1007,7 +1007,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
addr_buf = kaddrs;
while (walk_size < addrs_size) {
if (walk_size + sizeof(sa_family_t) > addrs_size) {
kvfree(kaddrs);
kfree(kaddrs);
return -EINVAL;
}
@ -1018,7 +1018,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
* causes the address buffer to overflow return EINVAL.
*/
if (!af || (walk_size + af->sockaddr_len) > addrs_size) {
kvfree(kaddrs);
kfree(kaddrs);
return -EINVAL;
}
addrcnt++;
@ -1054,7 +1054,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
}
out:
kvfree(kaddrs);
kfree(kaddrs);
return err;
}
@ -1329,7 +1329,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk,
if (unlikely(addrs_size <= 0))
return -EINVAL;
kaddrs = vmemdup_user(addrs, addrs_size);
kaddrs = memdup_user(addrs, addrs_size);
if (unlikely(IS_ERR(kaddrs)))
return PTR_ERR(kaddrs);
@ -1349,7 +1349,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk,
err = __sctp_connect(sk, kaddrs, addrs_size, flags, assoc_id);
out_free:
kvfree(kaddrs);
kfree(kaddrs);
return err;
}