[PATCH v1 net-next 0/4] af_unix: Correct manage_oob() when OOB follows a consumed OOB.

[PATCH v1 net-next 0/4] af_unix: Correct manage_oob() when OOB follows a consumed OOB.

[Kuniyuki Iwashima]

Recently syzkaller reported UAF of OOB skb.

The bug was introduced by commit 93c99f21db36 ("af_unix: Don't stop
recv(MSG_DONTWAIT) if consumed OOB skb is at the head.") but uncovered
by another recent commit 8594d9b85c07 ("af_unix: Don't call skb_get()
for OOB skb.").

This should be targeted for net.git, but it will introduce conflicts.
Given it's now rc6, I'll target this for net-next and later send
8594d9b85c07 and this series for stable.

[0]: https://lore.kernel.org/netdev/00000000000083b05a06214c9ddc@google.com/


Kuniyuki Iwashima (4):
  af_unix: Remove single nest in manage_oob().
  af_unix: Rename unlinked_skb in manage_oob().
  af_unix: Move spin_lock() in manage_oob().
  af_unix: Don't return OOB skb in manage_oob().

 net/unix/af_unix.c                            | 61 ++++++++++---------
 tools/testing/selftests/net/af_unix/msg_oob.c | 23 +++++++
 2 files changed, 56 insertions(+), 28 deletions(-)

-- 
2.30.2

[PATCH v1 net-next 1/4] af_unix: Remove single nest in manage_oob().

[Kuniyuki Iwashima]

This is a prep for the later fix.

No functional change intended.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/unix/af_unix.c | 45 +++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index a1894019ebd5..03820454bc72 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2654,11 +2654,10 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state)
 static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 				  int flags, int copied)
 {
+	struct sk_buff *unlinked_skb = NULL;
 	struct unix_sock *u = unix_sk(sk);
 
 	if (!unix_skb_len(skb)) {
-		struct sk_buff *unlinked_skb = NULL;
-
 		spin_lock(&sk->sk_receive_queue.lock);
 
 		if (copied && (!u->oob_skb || skb == u->oob_skb)) {
@@ -2674,31 +2673,33 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 		spin_unlock(&sk->sk_receive_queue.lock);
 
 		consume_skb(unlinked_skb);
-	} else {
-		struct sk_buff *unlinked_skb = NULL;
+		return skb;
+	}
 
-		spin_lock(&sk->sk_receive_queue.lock);
+	spin_lock(&sk->sk_receive_queue.lock);
 
-		if (skb == u->oob_skb) {
-			if (copied) {
-				skb = NULL;
-			} else if (!(flags & MSG_PEEK)) {
-				WRITE_ONCE(u->oob_skb, NULL);
-
-				if (!sock_flag(sk, SOCK_URGINLINE)) {
-					__skb_unlink(skb, &sk->sk_receive_queue);
-					unlinked_skb = skb;
-					skb = skb_peek(&sk->sk_receive_queue);
-				}
-			} else if (!sock_flag(sk, SOCK_URGINLINE)) {
-				skb = skb_peek_next(skb, &sk->sk_receive_queue);
-			}
-		}
+	if (skb != u->oob_skb)
+		goto unlock;
 
-		spin_unlock(&sk->sk_receive_queue.lock);
+	if (copied) {
+		skb = NULL;
+	} else if (!(flags & MSG_PEEK)) {
+		WRITE_ONCE(u->oob_skb, NULL);
 
-		kfree_skb(unlinked_skb);
+		if (!sock_flag(sk, SOCK_URGINLINE)) {
+			__skb_unlink(skb, &sk->sk_receive_queue);
+			unlinked_skb = skb;
+			skb = skb_peek(&sk->sk_receive_queue);
+		}
+	} else if (!sock_flag(sk, SOCK_URGINLINE)) {
+		skb = skb_peek_next(skb, &sk->sk_receive_queue);
 	}
+
+unlock:
+	spin_unlock(&sk->sk_receive_queue.lock);
+
+	kfree_skb(unlinked_skb);
+
 	return skb;
 }
 #endif
-- 
2.30.2

[PATCH v1 net-next 2/4] af_unix: Rename unlinked_skb in manage_oob().

[Kuniyuki Iwashima]

When OOB skb has been already consumed, manage_oob() returns the next
skb if exists.  In such a case, we need to fall back to the else branch
below.

Then, we need to keep two skbs and free them later with consume_skb()
and kfree_skb().

Let's rename unlinked_skb accordingly.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/unix/af_unix.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 03820454bc72..91d7877a1079 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2654,7 +2654,7 @@ static int unix_stream_recv_urg(struct unix_stream_read_state *state)
 static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 				  int flags, int copied)
 {
-	struct sk_buff *unlinked_skb = NULL;
+	struct sk_buff *read_skb = NULL, *unread_skb = NULL;
 	struct unix_sock *u = unix_sk(sk);
 
 	if (!unix_skb_len(skb)) {
@@ -2665,14 +2665,14 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 		} else if (flags & MSG_PEEK) {
 			skb = skb_peek_next(skb, &sk->sk_receive_queue);
 		} else {
-			unlinked_skb = skb;
+			read_skb = skb;
 			skb = skb_peek_next(skb, &sk->sk_receive_queue);
-			__skb_unlink(unlinked_skb, &sk->sk_receive_queue);
+			__skb_unlink(read_skb, &sk->sk_receive_queue);
 		}
 
 		spin_unlock(&sk->sk_receive_queue.lock);
 
-		consume_skb(unlinked_skb);
+		consume_skb(read_skb);
 		return skb;
 	}
 
@@ -2688,7 +2688,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 
 		if (!sock_flag(sk, SOCK_URGINLINE)) {
 			__skb_unlink(skb, &sk->sk_receive_queue);
-			unlinked_skb = skb;
+			unread_skb = skb;
 			skb = skb_peek(&sk->sk_receive_queue);
 		}
 	} else if (!sock_flag(sk, SOCK_URGINLINE)) {
@@ -2698,7 +2698,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 unlock:
 	spin_unlock(&sk->sk_receive_queue.lock);
 
-	kfree_skb(unlinked_skb);
+	kfree_skb(unread_skb);
 
 	return skb;
 }
-- 
2.30.2

[PATCH v1 net-next 3/4] af_unix: Move spin_lock() in manage_oob().

[Kuniyuki Iwashima]

When OOB skb has been already consumed, manage_oob() returns the next
skb if exists.  In such a case, we need to fall back to the else branch
below.

Then, we want to keep holding spin_lock(&sk->sk_receive_queue.lock).

Let's move it out of if-else branch and add lightweight check before
spin_lock() for major use cases without OOB skb.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/unix/af_unix.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 91d7877a1079..159d78fc3d14 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2657,9 +2657,12 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 	struct sk_buff *read_skb = NULL, *unread_skb = NULL;
 	struct unix_sock *u = unix_sk(sk);
 
-	if (!unix_skb_len(skb)) {
-		spin_lock(&sk->sk_receive_queue.lock);
+	if (likely(unix_skb_len(skb) && skb != READ_ONCE(u->oob_skb)))
+		return skb;
 
+	spin_lock(&sk->sk_receive_queue.lock);
+
+	if (!unix_skb_len(skb)) {
 		if (copied && (!u->oob_skb || skb == u->oob_skb)) {
 			skb = NULL;
 		} else if (flags & MSG_PEEK) {
@@ -2670,14 +2673,9 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 			__skb_unlink(read_skb, &sk->sk_receive_queue);
 		}
 
-		spin_unlock(&sk->sk_receive_queue.lock);
-
-		consume_skb(read_skb);
-		return skb;
+		goto unlock;
 	}
 
-	spin_lock(&sk->sk_receive_queue.lock);
-
 	if (skb != u->oob_skb)
 		goto unlock;
 
@@ -2698,6 +2696,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 unlock:
 	spin_unlock(&sk->sk_receive_queue.lock);
 
+	consume_skb(read_skb);
 	kfree_skb(unread_skb);
 
 	return skb;
-- 
2.30.2

[PATCH v1 net-next 4/4] af_unix: Don't return OOB skb in manage_oob().

[Kuniyuki Iwashima]

syzbot reported use-after-free in unix_stream_recv_urg(). [0]

The scenario is

  1. send(MSG_OOB)
  2. recv(MSG_OOB)
     -> The consumed OOB remains in recv queue
  3. send(MSG_OOB)
  4. recv()
     -> manage_oob() returns the next skb of the consumed OOB
     -> This is also OOB, but unix_sk(sk)->oob_skb is not cleared
  5. recv(MSG_OOB)
     -> unix_sk(sk)->oob_skb is used but already freed

The recent commit 8594d9b85c07 ("af_unix: Don't call skb_get() for OOB
skb.") uncovered the issue.

If the OOB skb is consumed and the next skb is peeked in manage_oob(),
we still need to check if the skb is OOB.

Let's do so by falling back to the following checks in manage_oob()
and add the test case in selftest.

Note that we need to add a similar check for SIOCATMARK.

[0]:
BUG: KASAN: slab-use-after-free in unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959
Read of size 4 at addr ffff8880326abcc4 by task syz-executor178/5235

CPU: 0 UID: 0 PID: 5235 Comm: syz-executor178 Not tainted 6.11.0-rc5-syzkaller-00742-gfbdaffe41adc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959
 unix_stream_recv_urg+0x1df/0x320 net/unix/af_unix.c:2640
 unix_stream_read_generic+0x2456/0x2520 net/unix/af_unix.c:2778
 unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x22f/0x280 net/socket.c:1068
 ____sys_recvmsg+0x1db/0x470 net/socket.c:2816
 ___sys_recvmsg net/socket.c:2858 [inline]
 __sys_recvmsg+0x2f0/0x3e0 net/socket.c:2888
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5360d6b4e9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff29b3a458 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00007fff29b3a638 RCX: 00007f5360d6b4e9
RDX: 0000000000002001 RSI: 0000000020000640 RDI: 0000000000000003
RBP: 00007f5360dde610 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff29b3a628 R14: 0000000000000001 R15: 0000000000000001
 </TASK>

Allocated by task 5235:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:312 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3988 [inline]
 slab_alloc_node mm/slub.c:4037 [inline]
 kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4080
 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667
 alloc_skb include/linux/skbuff.h:1320 [inline]
 alloc_skb_with_frags+0xc3/0x770 net/core/skbuff.c:6528
 sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2815
 sock_alloc_send_skb include/net/sock.h:1778 [inline]
 queue_oob+0x108/0x680 net/unix/af_unix.c:2198
 unix_stream_sendmsg+0xd24/0xf80 net/unix/af_unix.c:2351
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:745
 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597
 ___sys_sendmsg net/socket.c:2651 [inline]
 __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5235:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2252 [inline]
 slab_free mm/slub.c:4473 [inline]
 kmem_cache_free+0x145/0x350 mm/slub.c:4548
 unix_stream_read_generic+0x1ef6/0x2520 net/unix/af_unix.c:2917
 unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x22f/0x280 net/socket.c:1068
 __sys_recvfrom+0x256/0x3e0 net/socket.c:2255
 __do_sys_recvfrom net/socket.c:2273 [inline]
 __se_sys_recvfrom net/socket.c:2269 [inline]
 __x64_sys_recvfrom+0xde/0x100 net/socket.c:2269
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880326abc80
 which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 68 bytes inside of
 freed 240-byte region [ffff8880326abc80, ffff8880326abd70)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x326ab
ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 00fff00000000000 ffff88801eaee780 ffffea0000b7dc80 dead000000000003
raw: 0000000000000000 00000000800c000c 00000001fdffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 4686, tgid 4686 (udevadm), ts 32357469485, free_ts 28829011109
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4695
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x5f/0x120 mm/slub.c:2321
 allocate_slab+0x5a/0x2f0 mm/slub.c:2484
 new_slab mm/slub.c:2537 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3723
 __slab_alloc+0x58/0xa0 mm/slub.c:3813
 __slab_alloc_node mm/slub.c:3866 [inline]
 slab_alloc_node mm/slub.c:4025 [inline]
 kmem_cache_alloc_node_noprof+0x1fe/0x320 mm/slub.c:4080
 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667
 alloc_skb include/linux/skbuff.h:1320 [inline]
 alloc_uevent_skb+0x74/0x230 lib/kobject_uevent.c:289
 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
 kobject_uevent_net_broadcast+0x2fd/0x580 lib/kobject_uevent.c:410
 kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x4ef/0xae0 lib/kobject_uevent.c:207
 uevent_store+0x4b/0x70 drivers/base/bus.c:633
 kernfs_fop_write_iter+0x3a1/0x500 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa72/0xc90 fs/read_write.c:590
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2612
 kasan_depopulate_vmalloc_pte+0x74/0x90 mm/kasan/shadow.c:408
 apply_to_pte_range mm/memory.c:2797 [inline]
 apply_to_pmd_range mm/memory.c:2841 [inline]
 apply_to_pud_range mm/memory.c:2877 [inline]
 apply_to_p4d_range mm/memory.c:2913 [inline]
 __apply_to_page_range+0x8a8/0xe50 mm/memory.c:2947
 kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:525
 purge_vmap_node+0x3e3/0x770 mm/vmalloc.c:2208
 __purge_vmap_area_lazy+0x708/0xae0 mm/vmalloc.c:2290
 _vm_unmap_aliases+0x79d/0x840 mm/vmalloc.c:2885
 change_page_attr_set_clr+0x2fe/0xdb0 arch/x86/mm/pat/set_memory.c:1881
 change_page_attr_set arch/x86/mm/pat/set_memory.c:1922 [inline]
 set_memory_nx+0xf2/0x130 arch/x86/mm/pat/set_memory.c:2110
 free_init_pages arch/x86/mm/init.c:924 [inline]
 free_kernel_image_pages arch/x86/mm/init.c:943 [inline]
 free_initmem+0x79/0x110 arch/x86/mm/init.c:970
 kernel_init+0x31/0x2b0 init/main.c:1476
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff8880326abb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880326abc00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
>ffff8880326abc80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8880326abd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff8880326abd80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb

Fixes: 93c99f21db36 ("af_unix: Don't stop recv(MSG_DONTWAIT) if consumed OOB skb is at the head.")
Reported-by: syzbot+8811381d455e3e9ec788@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8811381d455e3e9ec788
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/unix/af_unix.c                            |  9 ++++++--
 tools/testing/selftests/net/af_unix/msg_oob.c | 23 +++++++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 159d78fc3d14..001ccc55ef0f 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2673,7 +2673,8 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 			__skb_unlink(read_skb, &sk->sk_receive_queue);
 		}
 
-		goto unlock;
+		if (!skb)
+			goto unlock;
 	}
 
 	if (skb != u->oob_skb)
@@ -3175,9 +3176,13 @@ static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 			skb = skb_peek(&sk->sk_receive_queue);
 			if (skb) {
 				struct sk_buff *oob_skb = READ_ONCE(u->oob_skb);
+				struct sk_buff *next_skb;
+
+				next_skb = skb_peek_next(skb, &sk->sk_receive_queue);
 
 				if (skb == oob_skb ||
-				    (!oob_skb && !unix_skb_len(skb)))
+				    (!unix_skb_len(skb) &&
+				     (!oob_skb || next_skb == oob_skb)))
 					answ = 1;
 			}
 
diff --git a/tools/testing/selftests/net/af_unix/msg_oob.c b/tools/testing/selftests/net/af_unix/msg_oob.c
index 535eb2c3d7d1..3ed3882a93b8 100644
--- a/tools/testing/selftests/net/af_unix/msg_oob.c
+++ b/tools/testing/selftests/net/af_unix/msg_oob.c
@@ -525,6 +525,29 @@ TEST_F(msg_oob, ex_oob_drop_2)
 	}
 }
 
+TEST_F(msg_oob, ex_oob_oob)
+{
+	sendpair("x", 1, MSG_OOB);
+	epollpair(true);
+	siocatmarkpair(true);
+
+	recvpair("x", 1, 1, MSG_OOB);
+	epollpair(false);
+	siocatmarkpair(true);
+
+	sendpair("y", 1, MSG_OOB);
+	epollpair(true);
+	siocatmarkpair(true);
+
+	recvpair("", -EAGAIN, 1, 0);
+	epollpair(false);
+	siocatmarkpair(false);
+
+	recvpair("", -EINVAL, 1, MSG_OOB);
+	epollpair(false);
+	siocatmarkpair(false);
+}
+
 TEST_F(msg_oob, ex_oob_ahead_break)
 {
 	sendpair("hello", 5, MSG_OOB);
-- 
2.30.2

Re: [PATCH v1 net-next 0/4] af_unix: Correct manage_oob() when OOB follows a consumed OOB.

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 5 Sep 2024 12:32:36 -0700 you wrote:
> Recently syzkaller reported UAF of OOB skb.
> 
> The bug was introduced by commit 93c99f21db36 ("af_unix: Don't stop
> recv(MSG_DONTWAIT) if consumed OOB skb is at the head.") but uncovered
> by another recent commit 8594d9b85c07 ("af_unix: Don't call skb_get()
> for OOB skb.").
> 
> [...]

Here is the summary with links:
  - [v1,net-next,1/4] af_unix: Remove single nest in manage_oob().
    https://git.kernel.org/netdev/net-next/c/579770dd8985
  - [v1,net-next,2/4] af_unix: Rename unlinked_skb in manage_oob().
    https://git.kernel.org/netdev/net-next/c/beb2c5f19b6a
  - [v1,net-next,3/4] af_unix: Move spin_lock() in manage_oob().
    https://git.kernel.org/netdev/net-next/c/a0264a9f51fe
  - [v1,net-next,4/4] af_unix: Don't return OOB skb in manage_oob().
    https://git.kernel.org/netdev/net-next/c/5aa57d9f2d53

You are awesome, thank you!
-- 
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