| Message ID | 2c54e352442c700440158d104c2bbc1ccbdf4ddf.1623232095.git.pabeni@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | a8b897c7bcd47f4147d066e22cc01d1026d7640e |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] udp: fix race between close() and udp_abort() | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | fail | 1 blamed authors not CCed: dsahern@kernel.org; 2 maintainers not CCed: yoshfuji@linux-ipv6.org dsahern@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 7 this patch: 7 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 35 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 7 this patch: 7 |
| netdev/header_inline | success | Link |
Hello: This patch was applied to netdev/net.git (refs/heads/master): On Wed, 9 Jun 2021 11:49:01 +0200 you wrote: > Kaustubh reported and diagnosed a panic in udp_lib_lookup(). > The root cause is udp_abort() racing with close(). Both > racing functions acquire the socket lock, but udp{v6}_destroy_sock() > release it before performing destructive actions. > > We can't easily extend the socket lock scope to avoid the race, > instead use the SOCK_DEAD flag to prevent udp_abort from doing > any action when the critical race happens. > > [...] Here is the summary with links: - [net] udp: fix race between close() and udp_abort() https://git.kernel.org/netdev/net/c/a8b897c7bcd4 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 055fceb18bea..bf98a87ac6e6 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2607,6 +2607,9 @@ void udp_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); bool slow = lock_sock_fast(sk); + + /* protects from races with udp_abort() */ + sock_set_flag(sk, SOCK_DEAD); udp_flush_pending_frames(sk); unlock_sock_fast(sk, slow); if (static_branch_unlikely(&udp_encap_needed_key)) { @@ -2857,10 +2860,17 @@ int udp_abort(struct sock *sk, int err) { lock_sock(sk); + /* udp{v6}_destroy_sock() sets it under the sk lock, avoid racing + * with close() + */ + if (sock_flag(sk, SOCK_DEAD)) + goto out; + sk->sk_err = err; sk->sk_error_report(sk); __udp_disconnect(sk, 0); +out: release_sock(sk); return 0; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 199b080d418a..3fcd86f4dfdc 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1598,6 +1598,9 @@ void udpv6_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); lock_sock(sk); + + /* protects from races with udp_abort() */ + sock_set_flag(sk, SOCK_DEAD); udp_v6_flush_pending_frames(sk); release_sock(sk);
Kaustubh reported and diagnosed a panic in udp_lib_lookup(). The root cause is udp_abort() racing with close(). Both racing functions acquire the socket lock, but udp{v6}_destroy_sock() release it before performing destructive actions. We can't easily extend the socket lock scope to avoid the race, instead use the SOCK_DEAD flag to prevent udp_abort from doing any action when the critical race happens. Diagnosed-and-tested-by: Kaustubh Pandey <kapandey@codeaurora.org> Fixes: 5d77dca82839 ("net: diag: support SOCK_DESTROY for UDP sockets") Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- net/ipv4/udp.c | 10 ++++++++++ net/ipv6/udp.c | 3 +++ 2 files changed, 13 insertions(+)