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| author | Michal Luczaj <mhal@rbox.co> | 2025-06-09 19:08:03 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-06-27 11:07:22 +0100 |
| commit | 8926a7ef1977a832dd6bf702f1a99303dbf15b15 (patch) | |
| tree | c9d0326ca2a52e8d39e9d6519c1576e2ce6dc927 /include/net | |
| parent | 356d09c7f5bf525086002a34f8bae40b134d1611 (diff) | |
| download | linux-8926a7ef1977a832dd6bf702f1a99303dbf15b15.tar.gz linux-8926a7ef1977a832dd6bf702f1a99303dbf15b15.tar.bz2 linux-8926a7ef1977a832dd6bf702f1a99303dbf15b15.zip | |
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/net')
| -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 e716b2ba00bb..e00cd9d0bec8 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -3061,8 +3061,11 @@ int sock_copy_user_timeval(struct __kernel_sock_timeval *tv, 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 */ |