From: Kuniyuki Iwashima <kuniyu@google.com> stable inclusion from stable-v6.6.95 commit 3902205eadf35db59dbc2186c2a98b9e6182efa5 category: bugfix bugzilla: ICK4OK CVE: CVE-2025-38190 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ------------------------------- 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> Signed-off-by: Ziming Du <duziming2@huawei.com> --- include/linux/atmdev.h | 6 ++++++ net/atm/common.c | 1 + net/atm/raw.c | 2 +- 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h index 9b02961d65ee..45f2f278b50a 100644 --- a/include/linux/atmdev.h +++ b/include/linux/atmdev.h @@ -249,6 +249,12 @@ static inline void atm_account_tx(struct atm_vcc *vcc, struct sk_buff *skb) 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); diff --git a/net/atm/common.c b/net/atm/common.c index f7019df41c3e..9cc82acbc735 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -635,6 +635,7 @@ int vcc_sendmsg(struct socket *sock, struct msghdr *m, size_t size) 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; diff --git a/net/atm/raw.c b/net/atm/raw.c index 2b5f78a7ec3e..1e6511ec842c 100644 --- a/net/atm/raw.c +++ b/net/atm/raw.c @@ -36,7 +36,7 @@ static void atm_pop_raw(struct atm_vcc *vcc, struct sk_buff *skb) 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); } -- 2.43.0