Commit ef82bcfa authored by Xin Long's avatar Xin Long Committed by David S. Miller

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 cacc0621
("sctp: use GFP_USER for user-controlled kmalloc").

However, since Commit c981f254 ("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: c981f254 ("sctp: use vmemdup_user() rather than badly open-coding memdup_user()")
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1c87e79a
...@@ -999,7 +999,7 @@ static int sctp_setsockopt_bindx(struct sock *sk, ...@@ -999,7 +999,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
if (unlikely(addrs_size <= 0)) if (unlikely(addrs_size <= 0))
return -EINVAL; return -EINVAL;
kaddrs = vmemdup_user(addrs, addrs_size); kaddrs = memdup_user(addrs, addrs_size);
if (unlikely(IS_ERR(kaddrs))) if (unlikely(IS_ERR(kaddrs)))
return PTR_ERR(kaddrs); return PTR_ERR(kaddrs);
...@@ -1007,7 +1007,7 @@ static int sctp_setsockopt_bindx(struct sock *sk, ...@@ -1007,7 +1007,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
addr_buf = kaddrs; addr_buf = kaddrs;
while (walk_size < addrs_size) { while (walk_size < addrs_size) {
if (walk_size + sizeof(sa_family_t) > addrs_size) { if (walk_size + sizeof(sa_family_t) > addrs_size) {
kvfree(kaddrs); kfree(kaddrs);
return -EINVAL; return -EINVAL;
} }
...@@ -1018,7 +1018,7 @@ static int sctp_setsockopt_bindx(struct sock *sk, ...@@ -1018,7 +1018,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
* causes the address buffer to overflow return EINVAL. * causes the address buffer to overflow return EINVAL.
*/ */
if (!af || (walk_size + af->sockaddr_len) > addrs_size) { if (!af || (walk_size + af->sockaddr_len) > addrs_size) {
kvfree(kaddrs); kfree(kaddrs);
return -EINVAL; return -EINVAL;
} }
addrcnt++; addrcnt++;
...@@ -1054,7 +1054,7 @@ static int sctp_setsockopt_bindx(struct sock *sk, ...@@ -1054,7 +1054,7 @@ static int sctp_setsockopt_bindx(struct sock *sk,
} }
out: out:
kvfree(kaddrs); kfree(kaddrs);
return err; return err;
} }
...@@ -1329,7 +1329,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk, ...@@ -1329,7 +1329,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk,
if (unlikely(addrs_size <= 0)) if (unlikely(addrs_size <= 0))
return -EINVAL; return -EINVAL;
kaddrs = vmemdup_user(addrs, addrs_size); kaddrs = memdup_user(addrs, addrs_size);
if (unlikely(IS_ERR(kaddrs))) if (unlikely(IS_ERR(kaddrs)))
return PTR_ERR(kaddrs); return PTR_ERR(kaddrs);
...@@ -1349,7 +1349,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk, ...@@ -1349,7 +1349,7 @@ static int __sctp_setsockopt_connectx(struct sock *sk,
err = __sctp_connect(sk, kaddrs, addrs_size, flags, assoc_id); err = __sctp_connect(sk, kaddrs, addrs_size, flags, assoc_id);
out_free: out_free:
kvfree(kaddrs); kfree(kaddrs);
return err; return err;
} }
......
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