CVE-2024-26733

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> arp: Prevent overflow in arp_req_get().<br /> <br /> syzkaller reported an overflown write in arp_req_get(). [0]<br /> <br /> When ioctl(SIOCGARP) is issued, arp_req_get() looks up an neighbour<br /> entry and copies neigh-&gt;ha to struct arpreq.arp_ha.sa_data.<br /> <br /> The arp_ha here is struct sockaddr, not struct sockaddr_storage, so<br /> the sa_data buffer is just 14 bytes.<br /> <br /> In the splat below, 2 bytes are overflown to the next int field,<br /> arp_flags. We initialise the field just after the memcpy(), so it&amp;#39;s<br /> not a problem.<br /> <br /> However, when dev-&gt;addr_len is greater than 22 (e.g. MAX_ADDR_LEN),<br /> arp_netmask is overwritten, which could be set as htonl(0xFFFFFFFFUL)<br /> in arp_ioctl() before calling arp_req_get().<br /> <br /> To avoid the overflow, let&amp;#39;s limit the max length of memcpy().<br /> <br /> Note that commit b5f0de6df6dc ("net: dev: Convert sa_data to flexible<br /> array in struct sockaddr") just silenced syzkaller.<br /> <br /> [0]:<br /> memcpy: detected field-spanning write (size 16) of single field "r-&gt;arp_ha.sa_data" at net/ipv4/arp.c:1128 (size 14)<br /> WARNING: CPU: 0 PID: 144638 at net/ipv4/arp.c:1128 arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128<br /> Modules linked in:<br /> CPU: 0 PID: 144638 Comm: syz-executor.4 Not tainted 6.1.74 #31<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014<br /> RIP: 0010:arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128<br /> Code: fd ff ff e8 41 42 de fb b9 0e 00 00 00 4c 89 fe 48 c7 c2 20 6d ab 87 48 c7 c7 80 6d ab 87 c6 05 25 af 72 04 01 e8 5f 8d ad fb 0b e9 6c fd ff ff e8 13 42 de fb be 03 00 00 00 4c 89 e7 e8 a6<br /> RSP: 0018:ffffc900050b7998 EFLAGS: 00010286<br /> RAX: 0000000000000000 RBX: ffff88803a815000 RCX: 0000000000000000<br /> RDX: 0000000000000000 RSI: ffffffff8641a44a RDI: 0000000000000001<br /> RBP: ffffc900050b7a98 R08: 0000000000000001 R09: 0000000000000000<br /> R10: 0000000000000000 R11: 203a7970636d656d R12: ffff888039c54000<br /> R13: 1ffff92000a16f37 R14: ffff88803a815084 R15: 0000000000000010<br /> FS: 00007f172bf306c0(0000) GS:ffff88805aa00000(0000) knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 00007f172b3569f0 CR3: 0000000057f12005 CR4: 0000000000770ef0<br /> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000<br /> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400<br /> PKRU: 55555554<br /> Call Trace:<br /> <br /> arp_ioctl+0x33f/0x4b0 net/ipv4/arp.c:1261<br /> inet_ioctl+0x314/0x3a0 net/ipv4/af_inet.c:981<br /> sock_do_ioctl+0xdf/0x260 net/socket.c:1204<br /> sock_ioctl+0x3ef/0x650 net/socket.c:1321<br /> vfs_ioctl fs/ioctl.c:51 [inline]<br /> __do_sys_ioctl fs/ioctl.c:870 [inline]<br /> __se_sys_ioctl fs/ioctl.c:856 [inline]<br /> __x64_sys_ioctl+0x18e/0x220 fs/ioctl.c:856<br /> do_syscall_x64 arch/x86/entry/common.c:51 [inline]<br /> do_syscall_64+0x37/0x90 arch/x86/entry/common.c:81<br /> entry_SYSCALL_64_after_hwframe+0x64/0xce<br /> RIP: 0033:0x7f172b262b8d<br /> Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 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:00007f172bf300b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010<br /> RAX: ffffffffffffffda RBX: 00007f172b3abf80 RCX: 00007f172b262b8d<br /> RDX: 0000000020000000 RSI: 0000000000008954 RDI: 0000000000000003<br /> RBP: 00007f172b2d3493 R08: 0000000000000000 R09: 0000000000000000<br /> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000<br /> R13: 000000000000000b R14: 00007f172b3abf80 R15: 00007f172bf10000<br />