diff options
| author | Michal Luczaj <mhal@rbox.co> | 2025-06-09 20:08:03 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-19 16:28:41 +0300 |
| commit | ff55c85a923e043d59d26b20a673a1b4a219c310 (patch) | |
| tree | 4f01395f868bd9159ab0b9783af4f732daa58433 /include | |
| parent | c6dad167aade4bf0bef9130f2f149f4249fc4ad0 (diff) | |
| download | linux-ff55c85a923e043d59d26b20a673a1b4a219c310.tar.xz | |
net: Fix TOCTOU issue in sk_is_readable()
[ Upstream commit 2660a544fdc0940bba15f70508a46cf9a6491230 ]
sk->sk_prot->sock_is_readable is a valid function pointer when sk resides
in a sockmap. After the last sk_psock_put() (which usually happens when
socket is removed from sockmap), sk->sk_prot gets restored and
sk->sk_prot->sock_is_readable becomes NULL.
This makes sk_is_readable() racy, if the value of sk->sk_prot is reloaded
after the initial check. Which in turn may lead to a null pointer
dereference.
Ensure the function pointer does not turn NULL after the check.
Fixes: 8934ce2fd081 ("bpf: sockmap redirect ingress support")
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250609-skisreadable-toctou-v1-1-d0dfb2d62c37@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/sock.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index dc625f94ee37..e15bea43b2ec 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -3043,8 +3043,11 @@ int sock_ioctl_inout(struct sock *sk, unsigned int cmd, int sk_ioctl(struct sock *sk, unsigned int cmd, void __user *arg); static inline bool sk_is_readable(struct sock *sk) { - if (sk->sk_prot->sock_is_readable) - return sk->sk_prot->sock_is_readable(sk); + const struct proto *prot = READ_ONCE(sk->sk_prot); + + if (prot->sock_is_readable) + return prot->sock_is_readable(sk); + return false; } #endif /* _SOCK_H */ |