[ upstream commit 0091bfc81741b8d3aeb3b7ab8636f911b2de6e80 ]

Instead of putting io_uring's registered files in unix_gc() we want it to be done by io_uring itself. The trick here is to consider io_uring registered files for cycle detection but not actually putting them down. Because io_uring can't register other ring instances, this will remove all refs to the ring file triggering the ->release path and clean up with io_ring_ctx_free().

Cc: stable@vger.kernel.org Fixes: 6b06314c47e1 ("io_uring: add file set registration") Reported-and-tested-by: David Bouman dbouman03@gmail.com Signed-off-by: Pavel Begunkov asml.silence@gmail.com Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com [axboe: add kerneldoc comment to skb, fold in skb leak fix] Signed-off-by: Jens Axboe axboe@kernel.dk --- fs/io_uring.c | 1 + include/linux/skbuff.h | 2 ++ net/unix/garbage.c | 20 ++++++++++++++++++++ 3 files changed, 23 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c index 501c7e14c07c..e8df6345a812 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3172,6 +3172,7 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset) }

skb->sk = sk; + skb->scm_io_uring = 1; skb->destructor = io_destruct_skb;

fpl->user = get_uid(ctx->user); diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 680f71ecdc08..eab3a4d02f32 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -659,6 +659,7 @@ typedef unsigned char *sk_buff_data_t; * @wifi_acked: whether frame was acked on wifi or not * @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS * @csum_not_inet: use CRC32c to resolve CHECKSUM_PARTIAL + * @scm_io_uring: SKB holds io_uring registered files * @dst_pending_confirm: need to confirm neighbour * @decrypted: Decrypted SKB * @napi_id: id of the NAPI struct this skb came from @@ -824,6 +825,7 @@ struct sk_buff { #ifdef CONFIG_TLS_DEVICE __u8 decrypted:1; #endif + __u8 scm_io_uring:1;

#ifdef CONFIG_NET_SCHED __u16 tc_index; /* traffic control index */ diff --git a/net/unix/garbage.c b/net/unix/garbage.c index d45d5366115a..dc2763540393 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -204,6 +204,7 @@ void wait_for_unix_gc(void) /* The external entry point: unix_gc() */ void unix_gc(void) { + struct sk_buff *next_skb, *skb; struct unix_sock *u; struct unix_sock *next; struct sk_buff_head hitlist; @@ -297,11 +298,30 @@ void unix_gc(void)

spin_unlock(&unix_gc_lock);

+ /* We need io_uring to clean its registered files, ignore all io_uring + * originated skbs. It's fine as io_uring doesn't keep references to + * other io_uring instances and so killing all other files in the cycle + * will put all io_uring references forcing it to go through normal + * release.path eventually putting registered files. + */ + skb_queue_walk_safe(&hitlist, skb, next_skb) { + if (skb->scm_io_uring) { + __skb_unlink(skb, &hitlist); + skb_queue_tail(&skb->sk->sk_receive_queue, skb); + } + } + /* Here we are. Hitlist is filled. Die. */ __skb_queue_purge(&hitlist);

spin_lock(&unix_gc_lock);

+ /* There could be io_uring registered files, just push them back to + * the inflight list + */ + list_for_each_entry_safe(u, next, &gc_candidates, link) + list_move_tail(&u->link, &gc_inflight_list); + /* All candidates should have been detached by now. */ BUG_ON(!list_empty(&gc_candidates));