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net: Fix data-races around sysctl_optmem_max.

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[ Upstream commit 7de6d09f51917c829af2b835aba8bb5040f8e86a ]

While reading sysctl_optmem_max, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kuniyuki Iwashima
2022-08-23 10:46:49 -07:00
committed by Greg Kroah-Hartman
parent 27e8ade792
commit ed48223f87
5 changed files with 18 additions and 14 deletions
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8
net/core/sock.c
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@@ -2219,7 +2219,7 @@ struct sk_buff *sock_omalloc(struct sock *sk, unsigned long size,
/* small safe race: SKB_TRUESIZE may differ from final skb->truesize */
if (atomic_read(&sk->sk_omem_alloc) + SKB_TRUESIZE(size) >
sysctl_optmem_max)
READ_ONCE(sysctl_optmem_max))
return NULL;
skb = alloc_skb(size, priority);
@@ -2237,8 +2237,10 @@ struct sk_buff *sock_omalloc(struct sock *sk, unsigned long size,
*/
void *sock_kmalloc(struct sock *sk, int size, gfp_t priority)
{
if ((unsigned int)size <= sysctl_optmem_max &&
atomic_read(&sk->sk_omem_alloc) + size < sysctl_optmem_max) {
int optmem_max = READ_ONCE(sysctl_optmem_max);
if ((unsigned int)size <= optmem_max &&
atomic_read(&sk->sk_omem_alloc) + size < optmem_max) {
void *mem;
/* First do the add, to avoid the race if kmalloc
* might sleep.