In the Linux kernel, the following vulnerability has been resolved:
net: prevent mss overflow in skb_segment()
Once again syzbot is able to crash the kernel in skb_segment() [1]
GSOBYFRAGS is a forbidden value, but unfortunately the following computation in skb_segment() can reach it quite easily :
mss = mss * partial_segs;
65535 = 3 * 5 * 17 * 257, so many initial values of mss can lead to a bad final result.
Make sure to limit segmentation so that the new mss value is smaller than GSOBYFRAGS.
[1]
general protection fault, probably for non-canonical address 0xdffffc000000000e: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077] CPU: 1 PID: 5079 Comm: syz-executor993 Not tainted 6.7.0-rc4-syzkaller-00141-g1ae4cd3cbdd0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023 RIP: 0010:skbsegment+0x181d/0x3f30 net/core/skbuff.c:4551 Code: 83 e3 02 e9 fb ed ff ff e8 90 68 1c f9 48 8b 84 24 f8 00 00 00 48 8d 78 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 8a 21 00 00 48 8b 84 24 f8 00 RSP: 0018:ffffc900043473d0 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000010046 RCX: ffffffff886b1597 RDX: 000000000000000e RSI: ffffffff886b2520 RDI: 0000000000000070 RBP: ffffc90004347578 R08: 0000000000000005 R09: 000000000000ffff R10: 000000000000ffff R11: 0000000000000002 R12: ffff888063202ac0 R13: 0000000000010000 R14: 000000000000ffff R15: 0000000000000046 FS: 0000555556e7e380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020010000 CR3: 0000000027ee2000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> udp6ufofragment+0xa0e/0xd00 net/ipv6/udpoffload.c:109 ipv6gsosegment+0x534/0x17e0 net/ipv6/ip6offload.c:120 skbmacgsosegment+0x290/0x610 net/core/gso.c:53 _skbgsosegment+0x339/0x710 net/core/gso.c:124 skbgsosegment include/net/gso.h:83 [inline] validatexmitskb+0x36c/0xeb0 net/core/dev.c:3626 _devqueuexmit+0x6f3/0x3d60 net/core/dev.c:4338 devqueuexmit include/linux/netdevice.h:3134 [inline] packetxmit+0x257/0x380 net/packet/afpacket.c:276 packetsnd net/packet/afpacket.c:3087 [inline] packetsendmsg+0x24c6/0x5220 net/packet/afpacket.c:3119 socksendmsgnosec net/socket.c:730 [inline] _socksendmsg+0xd5/0x180 net/socket.c:745 _syssendto+0x255/0x340 net/socket.c:2190 _dosyssendto net/socket.c:2202 [inline] _sesyssendto net/socket.c:2198 [inline] _x64syssendto+0xe0/0x1b0 net/socket.c:2198 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0x40/0x110 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x63/0x6b RIP: 0033:0x7f8692032aa9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 19 00 00 90 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:00007fff8d685418 EFLAGS: 00000246 ORIGRAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f8692032aa9 RDX: 0000000000010048 RSI: 00000000200000c0 RDI: 0000000000000003 RBP: 00000000000f4240 R08: 0000000020000540 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff8d685480 R13: 0000000000000001 R14: 00007fff8d685480 R15: 0000000000000003 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:skb_segment+0x181d/0x3f30 net/core/skbuff.c:4551 Code: 83 e3 02 e9 fb ed ff ff e8 90 68 1c f9 48 8b 84 24 f8 00 00 00 48 8d 78 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 8a 21 00 00 48 8b 84 24 f8 00 RSP: 0018:ffffc900043473d0 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000010046 RCX: ffffffff886b1597 RDX: 000000000000000e RSI: ffffffff886b2520 RDI: 0000000000000070 RBP: ffffc90004347578 R0 ---truncated---
{ "vanir_signatures": [ { "deprecated": false, "id": "CVE-2023-52435-059a5600", "digest": { "function_hash": "271290881552648785091583496774070136686", "length": 5932.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@989b0ff35fe5fc9652ee5bafbe8483db6f27b137", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" }, { "deprecated": false, "id": "CVE-2023-52435-2ce47783", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@95b3904a261a9f810205da560e802cc326f50d77", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-3c67659b", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@0d3ffbbf8631d6db0552f46250015648991c856f", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-43bd95b3", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@8f8f185643747fbb448de6aab0efa51c679909a3", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-47c4e136", "digest": { "function_hash": "183963699824010977654302706717415827475", "length": 5852.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@cd1022eaf87be8e6151435bd4df4c242c347e083", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" }, { "deprecated": false, "id": "CVE-2023-52435-5702aaae", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@989b0ff35fe5fc9652ee5bafbe8483db6f27b137", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-90f207b8", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@6c53e8547687d9c767c139cd4b50af566f58c29a", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-975e7cde", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@23d05d563b7e7b0314e65c8e882bc27eac2da8e7", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-9fb10fbf", "digest": { "function_hash": "53235915318869744066593526301713568030", "length": 5935.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@8f8f185643747fbb448de6aab0efa51c679909a3", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" }, { "deprecated": false, "id": "CVE-2023-52435-9ffd9ee4", "digest": { "function_hash": "271290881552648785091583496774070136686", "length": 5932.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@23d05d563b7e7b0314e65c8e882bc27eac2da8e7", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" }, { "deprecated": false, "id": "CVE-2023-52435-ab104ed7", "digest": { "function_hash": "271290881552648785091583496774070136686", "length": 5932.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@95b3904a261a9f810205da560e802cc326f50d77", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" }, { "deprecated": false, "id": "CVE-2023-52435-c61ee083", "digest": { "function_hash": "219273633841092988178959839721774956192", "length": 5855.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@0d3ffbbf8631d6db0552f46250015648991c856f", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" }, { "deprecated": false, "id": "CVE-2023-52435-ce2a50c9", "digest": { "threshold": 0.9, "line_hashes": [ "228455872691584065936176509457494479339", "271054891427998034995183458054028322455", "190476150054406541100957634051250458375", "155625475931011703031230768738929521716" ] }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@cd1022eaf87be8e6151435bd4df4c242c347e083", "target": { "file": "net/core/skbuff.c" }, "signature_version": "v1", "signature_type": "Line" }, { "deprecated": false, "id": "CVE-2023-52435-fe243bb9", "digest": { "function_hash": "271290881552648785091583496774070136686", "length": 5932.0 }, "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@6c53e8547687d9c767c139cd4b50af566f58c29a", "target": { "file": "net/core/skbuff.c", "function": "skb_segment" }, "signature_version": "v1", "signature_type": "Function" } ] }