CVE-2025-39828

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> atm: atmtcp: Prevent arbitrary write in atmtcp_recv_control().<br /> <br /> syzbot reported the splat below. [0]<br /> <br /> When atmtcp_v_open() or atmtcp_v_close() is called via connect()<br /> or close(), atmtcp_send_control() is called to send an in-kernel<br /> special message.<br /> <br /> The message has ATMTCP_HDR_MAGIC in atmtcp_control.hdr.length.<br /> Also, a pointer of struct atm_vcc is set to atmtcp_control.vcc.<br /> <br /> The notable thing is struct atmtcp_control is uAPI but has a<br /> space for an in-kernel pointer.<br /> <br /> struct atmtcp_control {<br /> struct atmtcp_hdr hdr; /* must be first */<br /> ...<br /> atm_kptr_t vcc; /* both directions */<br /> ...<br /> } __ATM_API_ALIGN;<br /> <br /> typedef struct { unsigned char _[8]; } __ATM_API_ALIGN atm_kptr_t;<br /> <br /> The special message is processed in atmtcp_recv_control() called<br /> from atmtcp_c_send().<br /> <br /> atmtcp_c_send() is vcc-&gt;dev-&gt;ops-&gt;send() and called from 2 paths:<br /> <br /> 1. .ndo_start_xmit() (vcc-&gt;send() == atm_send_aal0())<br /> 2. vcc_sendmsg()<br /> <br /> The problem is sendmsg() does not validate the message length and<br /> userspace can abuse atmtcp_recv_control() to overwrite any kptr<br /> by atmtcp_control.<br /> <br /> Let&amp;#39;s add a new -&gt;pre_send() hook to validate messages from sendmsg().<br /> <br /> [0]:<br /> Oops: general protection fault, probably for non-canonical address 0xdffffc00200000ab: 0000 [#1] SMP KASAN PTI<br /> KASAN: probably user-memory-access in range [0x0000000100000558-0x000000010000055f]<br /> CPU: 0 UID: 0 PID: 5865 Comm: syz-executor331 Not tainted 6.17.0-rc1-syzkaller-00215-gbab3ce404553 #0 PREEMPT(full)<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025<br /> RIP: 0010:atmtcp_recv_control drivers/atm/atmtcp.c:93 [inline]<br /> RIP: 0010:atmtcp_c_send+0x1da/0x950 drivers/atm/atmtcp.c:297<br /> Code: 4d 8d 75 1a 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 15 06 00 00 41 0f b7 1e 4d 8d b7 60 05 00 00 4c 89 f0 48 c1 e8 03 0f b6 04 20 84 c0 0f 85 13 06 00 00 66 41 89 1e 4d 8d 75 1c 4c<br /> RSP: 0018:ffffc90003f5f810 EFLAGS: 00010203<br /> RAX: 00000000200000ab RBX: 0000000000000000 RCX: 0000000000000000<br /> RDX: ffff88802a510000 RSI: 00000000ffffffff RDI: ffff888030a6068c<br /> RBP: ffff88802699fb40 R08: ffff888030a606eb R09: 1ffff1100614c0dd<br /> R10: dffffc0000000000 R11: ffffffff8718fc40 R12: dffffc0000000000<br /> R13: ffff888030a60680 R14: 000000010000055f R15: 00000000ffffffff<br /> FS: 00007f8d7e9236c0(0000) GS:ffff888125c1c000(0000) knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 000000000045ad50 CR3: 0000000075bde000 CR4: 00000000003526f0<br /> Call Trace:<br /> <br /> vcc_sendmsg+0xa10/0xc60 net/atm/common.c:645<br /> sock_sendmsg_nosec net/socket.c:714 [inline]<br /> __sock_sendmsg+0x219/0x270 net/socket.c:729<br /> ____sys_sendmsg+0x505/0x830 net/socket.c:2614<br /> ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668<br /> __sys_sendmsg net/socket.c:2700 [inline]<br /> __do_sys_sendmsg net/socket.c:2705 [inline]<br /> __se_sys_sendmsg net/socket.c:2703 [inline]<br /> __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703<br /> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]<br /> do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f<br /> RIP: 0033:0x7f8d7e96a4a9<br /> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 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 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48<br /> RSP: 002b:00007f8d7e923198 EFLAGS: 00000246 ORIG_RAX: 000000000000002e<br /> RAX: ffffffffffffffda RBX: 00007f8d7e9f4308 RCX: 00007f8d7e96a4a9<br /> RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000005<br /> RBP: 00007f8d7e9f4300 R08: 65732f636f72702f R09: 65732f636f72702f<br /> R10: 65732f636f72702f R11: 0000000000000246 R12: 00007f8d7e9c10ac<br /> R13: 00007f8d7e9231a0 R14: 0000200000000200 R15: 0000200000000250<br /> <br /> Modules linked in: