CVE-2021-46981 (GCVE-0-2021-46981)
Vulnerability from cvelistv5
Published
2024-02-28 08:13
Modified
2025-05-04 12:40
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: nbd: Fix NULL pointer in flush_workqueue Open /dev/nbdX first, the config_refs will be 1 and the pointers in nbd_device are still null. Disconnect /dev/nbdX, then reference a null recv_workq. The protection by config_refs in nbd_genl_disconnect is useless. [ 656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020 [ 656.368943] #PF: supervisor write access in kernel mode [ 656.369844] #PF: error_code(0x0002) - not-present page [ 656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0 [ 656.371693] Oops: 0002 [#1] SMP [ 656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1 [ 656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 [ 656.375904] RIP: 0010:mutex_lock+0x29/0x60 [ 656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 <f0> 48 0f b1 55 d [ 656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246 [ 656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020 [ 656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318 [ 656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40 [ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00 [ 656.382166] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000 [ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0 [ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 656.384927] Call Trace: [ 656.385111] flush_workqueue+0x92/0x6c0 [ 656.385395] nbd_disconnect_and_put+0x81/0xd0 [ 656.385716] nbd_genl_disconnect+0x125/0x2a0 [ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0 [ 656.386422] genl_rcv_msg+0xfc/0x2b0 [ 656.386685] ? nbd_ioctl+0x490/0x490 [ 656.386954] ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0 [ 656.387354] netlink_rcv_skb+0x62/0x180 [ 656.387638] genl_rcv+0x34/0x60 [ 656.387874] netlink_unicast+0x26d/0x590 [ 656.388162] netlink_sendmsg+0x398/0x6c0 [ 656.388451] ? netlink_rcv_skb+0x180/0x180 [ 656.388750] ____sys_sendmsg+0x1da/0x320 [ 656.389038] ? ____sys_recvmsg+0x130/0x220 [ 656.389334] ___sys_sendmsg+0x8e/0xf0 [ 656.389605] ? ___sys_recvmsg+0xa2/0xf0 [ 656.389889] ? handle_mm_fault+0x1671/0x21d0 [ 656.390201] __sys_sendmsg+0x6d/0xe0 [ 656.390464] __x64_sys_sendmsg+0x23/0x30 [ 656.390751] do_syscall_64+0x45/0x70 [ 656.391017] entry_SYSCALL_64_after_hwframe+0x44/0xa9 To fix it, just add if (nbd->recv_workq) to nbd_disconnect_and_put().
References
Impacted products
Vendor Product Version
Linux Linux Version: e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Version: e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Version: e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Version: e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Version: e9e006f5fcf2bab59149cb38a48a4817c1b538b4
Version: 0b584bf573ae59021069c056c22d65d5721910cb
Version: 9f0f39c92e4f50189155dfb13bb5524372e40eba
Version: 92ec11cccb7fc14331e000ab2337f60aa433433e
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    "cveId": "CVE-2021-46981",
    "datePublished": "2024-02-28T08:13:10.972Z",
    "dateReserved": "2024-02-27T18:42:55.945Z",
    "dateUpdated": "2025-05-04T12:40:42.413Z",
    "state": "PUBLISHED"
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    "vulnrichment": {
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Disconnect\\n/dev/nbdX, then reference a null recv_workq. The\\nprotection by config_refs in nbd_genl_disconnect is useless.\\n\\n[  656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020\\n[  656.368943] #PF: supervisor write access in kernel mode\\n[  656.369844] #PF: error_code(0x0002) - not-present page\\n[  656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0\\n[  656.371693] Oops: 0002 [#1] SMP\\n[  656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1\\n[  656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014\\n[  656.375904] RIP: 0010:mutex_lock+0x29/0x60\\n[  656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 \u003cf0\u003e 48 0f b1 55 d\\n[  656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246\\n[  656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000\\n[  656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020\\n[  656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318\\n[  656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40\\n[  656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00\\n[  656.382166] FS:  00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000\\n[  656.382806] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\\n[  656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0\\n[  656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\\n[  656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\\n[  656.384927] Call Trace:\\n[  656.385111]  flush_workqueue+0x92/0x6c0\\n[  656.385395]  nbd_disconnect_and_put+0x81/0xd0\\n[  656.385716]  nbd_genl_disconnect+0x125/0x2a0\\n[  656.386034]  genl_family_rcv_msg_doit.isra.0+0x102/0x1b0\\n[  656.386422]  genl_rcv_msg+0xfc/0x2b0\\n[  656.386685]  ? nbd_ioctl+0x490/0x490\\n[  656.386954]  ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0\\n[  656.387354]  netlink_rcv_skb+0x62/0x180\\n[  656.387638]  genl_rcv+0x34/0x60\\n[  656.387874]  netlink_unicast+0x26d/0x590\\n[  656.388162]  netlink_sendmsg+0x398/0x6c0\\n[  656.388451]  ? netlink_rcv_skb+0x180/0x180\\n[  656.388750]  ____sys_sendmsg+0x1da/0x320\\n[  656.389038]  ? ____sys_recvmsg+0x130/0x220\\n[  656.389334]  ___sys_sendmsg+0x8e/0xf0\\n[  656.389605]  ? ___sys_recvmsg+0xa2/0xf0\\n[  656.389889]  ? handle_mm_fault+0x1671/0x21d0\\n[  656.390201]  __sys_sendmsg+0x6d/0xe0\\n[  656.390464]  __x64_sys_sendmsg+0x23/0x30\\n[  656.390751]  do_syscall_64+0x45/0x70\\n[  656.391017]  entry_SYSCALL_64_after_hwframe+0x44/0xa9\\n\\nTo fix it, just add if (nbd-\u003erecv_workq) to nbd_disconnect_and_put().\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.4.120\", \"versionStartIncluding\": \"5.4\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.38\", \"versionStartIncluding\": \"5.4\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.11.22\", \"versionStartIncluding\": \"5.4\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.12.5\", \"versionStartIncluding\": \"5.4\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.13\", \"versionStartIncluding\": \"5.4\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"4.14.149\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"4.19.79\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"5.3.6\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2025-05-04T12:40:42.413Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2021-46981\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2025-05-04T12:40:42.413Z\", \"dateReserved\": \"2024-02-27T18:42:55.945Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-02-28T08:13:10.972Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}


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