ghsa-gchp-wf2c-v3qv
Vulnerability from github
Published
2024-12-27 15:31
Modified
2024-12-27 15:31
Details

In the Linux kernel, the following vulnerability has been resolved:

tcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg

The current sk memory accounting logic in __SK_REDIRECT is pre-uncharging tosend bytes, which is either msg->sg.size or a smaller value apply_bytes.

Potential problems with this strategy are as follows:

  • If the actual sent bytes are smaller than tosend, we need to charge some bytes back, as in line 487, which is okay but seems not clean.

  • When tosend is set to apply_bytes, as in line 417, and (ret < 0), we may miss uncharging (msg->sg.size - apply_bytes) bytes.

[...] 415 tosend = msg->sg.size; 416 if (psock->apply_bytes && psock->apply_bytes < tosend) 417 tosend = psock->apply_bytes; [...] 443 sk_msg_return(sk, msg, tosend); 444 release_sock(sk); 446 origsize = msg->sg.size; 447 ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress, 448 msg, tosend, flags); 449 sent = origsize - msg->sg.size; [...] 454 lock_sock(sk); 455 if (unlikely(ret < 0)) { 456 int free = sk_msg_free_nocharge(sk, msg); 458 if (!cork) 459 *copied -= free; 460 } [...] 487 if (eval == __SK_REDIRECT) 488 sk_mem_charge(sk, tosend - sent); [...]

When running the selftest test_txmsg_redir_wait_sndmem with txmsg_apply, the following warning will be reported:

------------[ cut here ]------------ WARNING: CPU: 6 PID: 57 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x190/0x1a0 Modules linked in: CPU: 6 UID: 0 PID: 57 Comm: kworker/6:0 Not tainted 6.12.0-rc1.bm.1-amd64+ #43 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Workqueue: events sk_psock_destroy RIP: 0010:inet_sock_destruct+0x190/0x1a0 RSP: 0018:ffffad0a8021fe08 EFLAGS: 00010206 RAX: 0000000000000011 RBX: ffff9aab4475b900 RCX: ffff9aab481a0800 RDX: 0000000000000303 RSI: 0000000000000011 RDI: ffff9aab4475b900 RBP: ffff9aab4475b990 R08: 0000000000000000 R09: ffff9aab40050ec0 R10: 0000000000000000 R11: ffff9aae6fdb1d01 R12: ffff9aab49c60400 R13: ffff9aab49c60598 R14: ffff9aab49c60598 R15: dead000000000100 FS: 0000000000000000(0000) GS:ffff9aae6fd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffec7e47bd8 CR3: 00000001a1a1c004 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: ? __warn+0x89/0x130 ? inet_sock_destruct+0x190/0x1a0 ? report_bug+0xfc/0x1e0 ? handle_bug+0x5c/0xa0 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? inet_sock_destruct+0x190/0x1a0 __sk_destruct+0x25/0x220 sk_psock_destroy+0x2b2/0x310 process_scheduled_works+0xa3/0x3e0 worker_thread+0x117/0x240 ? __pfx_worker_thread+0x10/0x10 kthread+0xcf/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x40 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 ---[ end trace 0000000000000000 ]---

In __SK_REDIRECT, a more concise way is delaying the uncharging after sent bytes are finalized, and uncharge this value. When (ret < 0), we shall invoke sk_msg_free.

Same thing happens in case __SK_DROP, when tosend is set to apply_bytes, we may miss uncharging (msg->sg.size - apply_bytes) bytes. The same warning will be reported in selftest.

[...] 468 case __SK_DROP: 469 default: 470 sk_msg_free_partial(sk, msg, tosend); 471 sk_msg_apply_bytes(psock, tosend); 472 *copied -= (tosend + delta); 473 return -EACCES; [...]

So instead of sk_msg_free_partial we can do sk_msg_free here.

Show details on source website

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{
   affected: [],
   aliases: [
      "CVE-2024-56633",
   ],
   database_specific: {
      cwe_ids: [],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-12-27T15:15:22Z",
      severity: null,
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg\n\nThe current sk memory accounting logic in __SK_REDIRECT is pre-uncharging\ntosend bytes, which is either msg->sg.size or a smaller value apply_bytes.\n\nPotential problems with this strategy are as follows:\n\n- If the actual sent bytes are smaller than tosend, we need to charge some\n  bytes back, as in line 487, which is okay but seems not clean.\n\n- When tosend is set to apply_bytes, as in line 417, and (ret < 0), we may\n  miss uncharging (msg->sg.size - apply_bytes) bytes.\n\n[...]\n415 tosend = msg->sg.size;\n416 if (psock->apply_bytes && psock->apply_bytes < tosend)\n417   tosend = psock->apply_bytes;\n[...]\n443 sk_msg_return(sk, msg, tosend);\n444 release_sock(sk);\n446 origsize = msg->sg.size;\n447 ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,\n448                             msg, tosend, flags);\n449 sent = origsize - msg->sg.size;\n[...]\n454 lock_sock(sk);\n455 if (unlikely(ret < 0)) {\n456   int free = sk_msg_free_nocharge(sk, msg);\n458   if (!cork)\n459     *copied -= free;\n460 }\n[...]\n487 if (eval == __SK_REDIRECT)\n488   sk_mem_charge(sk, tosend - sent);\n[...]\n\nWhen running the selftest test_txmsg_redir_wait_sndmem with txmsg_apply,\nthe following warning will be reported:\n\n------------[ cut here ]------------\nWARNING: CPU: 6 PID: 57 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x190/0x1a0\nModules linked in:\nCPU: 6 UID: 0 PID: 57 Comm: kworker/6:0 Not tainted 6.12.0-rc1.bm.1-amd64+ #43\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\nWorkqueue: events sk_psock_destroy\nRIP: 0010:inet_sock_destruct+0x190/0x1a0\nRSP: 0018:ffffad0a8021fe08 EFLAGS: 00010206\nRAX: 0000000000000011 RBX: ffff9aab4475b900 RCX: ffff9aab481a0800\nRDX: 0000000000000303 RSI: 0000000000000011 RDI: ffff9aab4475b900\nRBP: ffff9aab4475b990 R08: 0000000000000000 R09: ffff9aab40050ec0\nR10: 0000000000000000 R11: ffff9aae6fdb1d01 R12: ffff9aab49c60400\nR13: ffff9aab49c60598 R14: ffff9aab49c60598 R15: dead000000000100\nFS:  0000000000000000(0000) GS:ffff9aae6fd80000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007ffec7e47bd8 CR3: 00000001a1a1c004 CR4: 0000000000770ef0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nPKRU: 55555554\nCall Trace:\n<TASK>\n? __warn+0x89/0x130\n? inet_sock_destruct+0x190/0x1a0\n? report_bug+0xfc/0x1e0\n? handle_bug+0x5c/0xa0\n? exc_invalid_op+0x17/0x70\n? asm_exc_invalid_op+0x1a/0x20\n? inet_sock_destruct+0x190/0x1a0\n__sk_destruct+0x25/0x220\nsk_psock_destroy+0x2b2/0x310\nprocess_scheduled_works+0xa3/0x3e0\nworker_thread+0x117/0x240\n? __pfx_worker_thread+0x10/0x10\nkthread+0xcf/0x100\n? __pfx_kthread+0x10/0x10\nret_from_fork+0x31/0x40\n? __pfx_kthread+0x10/0x10\nret_from_fork_asm+0x1a/0x30\n</TASK>\n---[ end trace 0000000000000000 ]---\n\nIn __SK_REDIRECT, a more concise way is delaying the uncharging after sent\nbytes are finalized, and uncharge this value. When (ret < 0), we shall\ninvoke sk_msg_free.\n\nSame thing happens in case __SK_DROP, when tosend is set to apply_bytes,\nwe may miss uncharging (msg->sg.size - apply_bytes) bytes. The same\nwarning will be reported in selftest.\n\n[...]\n468 case __SK_DROP:\n469 default:\n470 sk_msg_free_partial(sk, msg, tosend);\n471 sk_msg_apply_bytes(psock, tosend);\n472 *copied -= (tosend + delta);\n473 return -EACCES;\n[...]\n\nSo instead of sk_msg_free_partial we can do sk_msg_free here.",
   id: "GHSA-gchp-wf2c-v3qv",
   modified: "2024-12-27T15:31:55Z",
   published: "2024-12-27T15:31:55Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-56633",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/0d6cd1151e26fc7c2d5daa85e8984aaa685a1a12",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/206d56f41a1509cadd06e2178c26cb830e45057d",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/456f08d24afa51b5eb816c42e4ca1c44a247bd42",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/5c9e3bb43a354a2245caebbbbb4a5b8c034fdd56",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/905d82e6e77d16ec3e089c92b7b59a14899dfc1a",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/ca70b8baf2bd125b2a4d96e76db79375c07d7ff2",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/dbedc7e142df5ea238a46fdd7462c1c42cd36a10",
      },
   ],
   schema_version: "1.4.0",
   severity: [],
}


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