5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kuniyuki Iwashima kuniyu@google.com
commit 7851263998d4269125fd6cb3fdbfc7c6db853859 upstream.
In vcc_sendmsg(), we account skb->truesize to sk->sk_wmem_alloc by atm_account_tx().
It is expected to be reverted by atm_pop_raw() later called by vcc->dev->ops->send(vcc, skb).
However, vcc_sendmsg() misses the same revert when copy_from_iter_full() fails, and then we will leak a socket.
Let's factorise the revert part as atm_return_tx() and call it in the failure path.
Note that the corresponding sk_wmem_alloc operation can be found in alloc_tx() as of the blamed commit.
$ git blame -L:alloc_tx net/atm/common.c c55fa3cccbc2c~
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Simon Horman horms@kernel.org Closes: https://lore.kernel.org/netdev/20250614161959.GR414686@horms.kernel.org/ Signed-off-by: Kuniyuki Iwashima kuniyu@google.com Link: https://patch.msgid.link/20250616182147.963333-3-kuni1840@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/atmdev.h | 6 ++++++ net/atm/common.c | 1 + net/atm/raw.c | 2 +- 3 files changed, 8 insertions(+), 1 deletion(-)
--- a/include/linux/atmdev.h +++ b/include/linux/atmdev.h @@ -257,6 +257,12 @@ static inline void atm_account_tx(struct ATM_SKB(skb)->atm_options = vcc->atm_options; }
+static inline void atm_return_tx(struct atm_vcc *vcc, struct sk_buff *skb) +{ + WARN_ON_ONCE(refcount_sub_and_test(ATM_SKB(skb)->acct_truesize, + &sk_atm(vcc)->sk_wmem_alloc)); +} + static inline void atm_force_charge(struct atm_vcc *vcc,int truesize) { atomic_add(truesize, &sk_atm(vcc)->sk_rmem_alloc); --- a/net/atm/common.c +++ b/net/atm/common.c @@ -635,6 +635,7 @@ int vcc_sendmsg(struct socket *sock, str
skb->dev = NULL; /* for paths shared with net_device interfaces */ if (!copy_from_iter_full(skb_put(skb, size), size, &m->msg_iter)) { + atm_return_tx(vcc, skb); kfree_skb(skb); error = -EFAULT; goto out; --- a/net/atm/raw.c +++ b/net/atm/raw.c @@ -36,7 +36,7 @@ static void atm_pop_raw(struct atm_vcc *
pr_debug("(%d) %d -= %d\n", vcc->vci, sk_wmem_alloc_get(sk), ATM_SKB(skb)->acct_truesize); - WARN_ON(refcount_sub_and_test(ATM_SKB(skb)->acct_truesize, &sk->sk_wmem_alloc)); + atm_return_tx(vcc, skb); dev_kfree_skb_any(skb); sk->sk_write_space(sk); }