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Merge branch 'mptcp-prevent-tcp_push-crash-and-selftest-temp-file-buildup'

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Mat Martineau says:

====================
mptcp: Prevent tcp_push() crash and selftest temp file buildup

These are two fixes for the net tree, addressing separate issues.

Patch 1 addresses a divide-by-zero crash seen in syzkaller and also
reported by a user on the netdev list. This changes MPTCP code so
tcp_push() cannot be called with an invalid (0) mss_now value.

Patch 2 fixes a selftest temp file cleanup issue that consumes excessive
disk space when running repeated tests.
====================

Link: https://lore.kernel.org/r/20210901171537.121255-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2021-09-01 10:55:51 -07:00
commit 36e784a60b
2 changed files with 37 additions and 43 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

76
net/mptcp/protocol.c
View file

@ -1003,6 +1003,13 @@ static void mptcp_wmem_uncharge(struct sock *sk, int size)
msk->wmem_reserved += size;
}
static void __mptcp_mem_reclaim_partial(struct sock *sk)
{
lockdep_assert_held_once(&sk->sk_lock.slock);
__mptcp_update_wmem(sk);
sk_mem_reclaim_partial(sk);
}
static void mptcp_mem_reclaim_partial(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
@ -1094,12 +1101,8 @@ static void __mptcp_clean_una(struct sock *sk)
msk->recovery = false;
out:
if (cleaned) {
if (tcp_under_memory_pressure(sk)) {
__mptcp_update_wmem(sk);
sk_mem_reclaim_partial(sk);
}
}
if (cleaned && tcp_under_memory_pressure(sk))
__mptcp_mem_reclaim_partial(sk);
if (snd_una == READ_ONCE(msk->snd_nxt) && !msk->recovery) {
if (mptcp_timer_pending(sk) && !mptcp_data_fin_enabled(msk))
@ -1179,6 +1182,7 @@ struct mptcp_sendmsg_info {
u16 limit;
u16 sent;
unsigned int flags;
bool data_lock_held;
};
static int mptcp_check_allowed_size(struct mptcp_sock *msk, u64 data_seq,
@ -1250,17 +1254,17 @@ static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp)
return false;
}
static bool mptcp_must_reclaim_memory(struct sock *sk, struct sock *ssk)
static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, bool data_lock_held)
{
return !ssk->sk_tx_skb_cache &&
tcp_under_memory_pressure(sk);
}
gfp_t gfp = data_lock_held ? GFP_ATOMIC : sk->sk_allocation;
static bool mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk)
{
if (unlikely(mptcp_must_reclaim_memory(sk, ssk)))
mptcp_mem_reclaim_partial(sk);
return __mptcp_alloc_tx_skb(sk, ssk, sk->sk_allocation);
if (unlikely(tcp_under_memory_pressure(sk))) {
if (data_lock_held)
__mptcp_mem_reclaim_partial(sk);
else
mptcp_mem_reclaim_partial(sk);
}
return __mptcp_alloc_tx_skb(sk, ssk, gfp);
}
/* note: this always recompute the csum on the whole skb, even
@ -1284,7 +1288,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
bool zero_window_probe = false;
struct mptcp_ext *mpext = NULL;
struct sk_buff *skb, *tail;
bool can_collapse = false;
bool must_collapse = false;
int size_bias = 0;
int avail_size;
size_t ret = 0;
@ -1304,16 +1308,24 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
* SSN association set here
*/
mpext = skb_ext_find(skb, SKB_EXT_MPTCP);
can_collapse = (info->size_goal - skb->len > 0) &&
mptcp_skb_can_collapse_to(data_seq, skb, mpext);
if (!can_collapse) {
if (!mptcp_skb_can_collapse_to(data_seq, skb, mpext)) {
TCP_SKB_CB(skb)->eor = 1;
} else {
goto alloc_skb;
}
must_collapse = (info->size_goal - skb->len > 0) &&
(skb_shinfo(skb)->nr_frags < sysctl_max_skb_frags);
if (must_collapse) {
size_bias = skb->len;
avail_size = info->size_goal - skb->len;
}
}
alloc_skb:
if (!must_collapse && !ssk->sk_tx_skb_cache &&
!mptcp_alloc_tx_skb(sk, ssk, info->data_lock_held))
return 0;
/* Zero window and all data acked? Probe. */
avail_size = mptcp_check_allowed_size(msk, data_seq, avail_size);
if (avail_size == 0) {
@ -1343,7 +1355,6 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
if (skb == tail) {
TCP_SKB_CB(tail)->tcp_flags &= ~TCPHDR_PSH;
mpext->data_len += ret;
WARN_ON_ONCE(!can_collapse);
WARN_ON_ONCE(zero_window_probe);
goto out;
}
@ -1530,15 +1541,6 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
if (ssk != prev_ssk)
lock_sock(ssk);
/* keep it simple and always provide a new skb for the
* subflow, even if we will not use it when collapsing
* on the pending one
*/
if (!mptcp_alloc_tx_skb(sk, ssk)) {
mptcp_push_release(sk, ssk, &info);
goto out;
}
ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
if (ret <= 0) {
mptcp_push_release(sk, ssk, &info);
@ -1571,7 +1573,9 @@ out:
static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_sendmsg_info info;
struct mptcp_sendmsg_info info = {
.data_lock_held = true,
};
struct mptcp_data_frag *dfrag;
struct sock *xmit_ssk;
int len, copied = 0;
@ -1597,13 +1601,6 @@ static void __mptcp_subflow_push_pending(struct sock *sk, struct sock *ssk)
goto out;
}
if (unlikely(mptcp_must_reclaim_memory(sk, ssk))) {
__mptcp_update_wmem(sk);
sk_mem_reclaim_partial(sk);
}
if (!__mptcp_alloc_tx_skb(sk, ssk, GFP_ATOMIC))
goto out;
ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
if (ret <= 0)
goto out;
@ -2409,9 +2406,6 @@ static void __mptcp_retrans(struct sock *sk)
info.sent = 0;
info.limit = READ_ONCE(msk->csum_enabled) ? dfrag->data_len : dfrag->already_sent;
while (info.sent < info.limit) {
if (!mptcp_alloc_tx_skb(sk, ssk))
break;
ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
if (ret <= 0)
break;

4
tools/testing/selftests/net/mptcp/simult_flows.sh
View file

@ -22,8 +22,8 @@ usage() {
cleanup()
{
rm -f "$cin" "$cout"
rm -f "$sin" "$sout"
rm -f "$cout" "$sout"
rm -f "$large" "$small"
rm -f "$capout"
local netns