{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2021-46981","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-02-27T18:42:55.945Z","datePublished":"2024-02-28T08:13:10.972Z","dateUpdated":"2025-05-04T12:40:42.413Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2025-05-04T12:40:42.413Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: Fix NULL pointer in flush_workqueue\n\nOpen /dev/nbdX first, the config_refs will be 1 and\nthe pointers in nbd_device are still null. 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 <f0> 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->recv_workq) to nbd_disconnect_and_put()."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/block/nbd.c"],"versions":[{"version":"e9e006f5fcf2bab59149cb38a48a4817c1b538b4","lessThan":"1c4962df938891af9ab4775f5224ef8601764107","status":"affected","versionType":"git"},{"version":"e9e006f5fcf2bab59149cb38a48a4817c1b538b4","lessThan":"cde4b55cfb24522dcbba80bbdb0c082303e76c43","status":"affected","versionType":"git"},{"version":"e9e006f5fcf2bab59149cb38a48a4817c1b538b4","lessThan":"b31d237796fd618379ec8e0f4de3370b5e4aeee7","status":"affected","versionType":"git"},{"version":"e9e006f5fcf2bab59149cb38a48a4817c1b538b4","lessThan":"54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc","status":"affected","versionType":"git"},{"version":"e9e006f5fcf2bab59149cb38a48a4817c1b538b4","lessThan":"79ebe9110fa458d58f1fceb078e2068d7ad37390","status":"affected","versionType":"git"},{"version":"0b584bf573ae59021069c056c22d65d5721910cb","status":"affected","versionType":"git"},{"version":"9f0f39c92e4f50189155dfb13bb5524372e40eba","status":"affected","versionType":"git"},{"version":"92ec11cccb7fc14331e000ab2337f60aa433433e","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/block/nbd.c"],"versions":[{"version":"5.4","status":"affected"},{"version":"0","lessThan":"5.4","status":"unaffected","versionType":"semver"},{"version":"5.4.120","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.38","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.11.22","lessThanOrEqual":"5.11.*","status":"unaffected","versionType":"semver"},{"version":"5.12.5","lessThanOrEqual":"5.12.*","status":"unaffected","versionType":"semver"},{"version":"5.13","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.4.120"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.10.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.11.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.12.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"5.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14.149"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.19.79"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.3.6"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107"},{"url":"https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43"},{"url":"https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7"},{"url":"https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc"},{"url":"https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390"}],"title":"nbd: Fix NULL pointer in flush_workqueue","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2021-46981","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-02-28T19:55:25.767523Z"}}}],"providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-06-04T17:13:11.297Z"}},{"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-08-04T05:24:38.514Z"},"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390","tags":["x_transferred"]}]}]}}