CVE-2024-47711

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> af_unix: Don&amp;#39;t return OOB skb in manage_oob().<br /> <br /> syzbot reported use-after-free in unix_stream_recv_urg(). [0]<br /> <br /> The scenario is<br /> <br /> 1. send(MSG_OOB)<br /> 2. recv(MSG_OOB)<br /> -&gt; The consumed OOB remains in recv queue<br /> 3. send(MSG_OOB)<br /> 4. recv()<br /> -&gt; manage_oob() returns the next skb of the consumed OOB<br /> -&gt; This is also OOB, but unix_sk(sk)-&gt;oob_skb is not cleared<br /> 5. recv(MSG_OOB)<br /> -&gt; unix_sk(sk)-&gt;oob_skb is used but already freed<br /> <br /> The recent commit 8594d9b85c07 ("af_unix: Don&amp;#39;t call skb_get() for OOB<br /> skb.") uncovered the issue.<br /> <br /> If the OOB skb is consumed and the next skb is peeked in manage_oob(),<br /> we still need to check if the skb is OOB.<br /> <br /> Let&amp;#39;s do so by falling back to the following checks in manage_oob()<br /> and add the test case in selftest.<br /> <br /> Note that we need to add a similar check for SIOCATMARK.<br /> <br /> [0]:<br /> BUG: KASAN: slab-use-after-free in unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959<br /> Read of size 4 at addr ffff8880326abcc4 by task syz-executor178/5235<br /> <br /> CPU: 0 UID: 0 PID: 5235 Comm: syz-executor178 Not tainted 6.11.0-rc5-syzkaller-00742-gfbdaffe41adc #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024<br /> Call Trace:<br /> <br /> __dump_stack lib/dump_stack.c:93 [inline]<br /> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119<br /> print_address_description mm/kasan/report.c:377 [inline]<br /> print_report+0x169/0x550 mm/kasan/report.c:488<br /> kasan_report+0x143/0x180 mm/kasan/report.c:601<br /> unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959<br /> unix_stream_recv_urg+0x1df/0x320 net/unix/af_unix.c:2640<br /> unix_stream_read_generic+0x2456/0x2520 net/unix/af_unix.c:2778<br /> unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996<br /> sock_recvmsg_nosec net/socket.c:1046 [inline]<br /> sock_recvmsg+0x22f/0x280 net/socket.c:1068<br /> ____sys_recvmsg+0x1db/0x470 net/socket.c:2816<br /> ___sys_recvmsg net/socket.c:2858 [inline]<br /> __sys_recvmsg+0x2f0/0x3e0 net/socket.c:2888<br /> do_syscall_x64 arch/x86/entry/common.c:52 [inline]<br /> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f<br /> RIP: 0033:0x7f5360d6b4e9<br /> 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 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48<br /> RSP: 002b:00007fff29b3a458 EFLAGS: 00000246 ORIG_RAX: 000000000000002f<br /> RAX: ffffffffffffffda RBX: 00007fff29b3a638 RCX: 00007f5360d6b4e9<br /> RDX: 0000000000002001 RSI: 0000000020000640 RDI: 0000000000000003<br /> RBP: 00007f5360dde610 R08: 0000000000000000 R09: 0000000000000000<br /> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001<br /> R13: 00007fff29b3a628 R14: 0000000000000001 R15: 0000000000000001<br /> <br /> <br /> Allocated by task 5235:<br /> kasan_save_stack mm/kasan/common.c:47 [inline]<br /> kasan_save_track+0x3f/0x80 mm/kasan/common.c:68<br /> unpoison_slab_object mm/kasan/common.c:312 [inline]<br /> __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338<br /> kasan_slab_alloc include/linux/kasan.h:201 [inline]<br /> slab_post_alloc_hook mm/slub.c:3988 [inline]<br /> slab_alloc_node mm/slub.c:4037 [inline]<br /> kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4080<br /> __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667<br /> alloc_skb include/linux/skbuff.h:1320 [inline]<br /> alloc_skb_with_frags+0xc3/0x770 net/core/skbuff.c:6528<br /> sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2815<br /> sock_alloc_send_skb include/net/sock.h:1778 [inline]<br /> queue_oob+0x108/0x680 net/unix/af_unix.c:2198<br /> unix_stream_sendmsg+0xd24/0xf80 net/unix/af_unix.c:2351<br /> sock_sendmsg_nosec net/socket.c:730 [inline]<br /> __sock_sendmsg+0x221/0x270 net/socket.c:745<br /> ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597<br /> ___sys_sendmsg net/socket.c:2651 [inline]<br /> __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680<br /> do_syscall_x64 arch/x86/entry/common.c:52 [inline]<br /> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f<br /> <br /> Freed by task 5235:<br /> kasan_save_stack mm/kasan/common.c:47<br /> ---truncated---