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Amazon Linux AMI 2: CVE-2021-46981: Security patch for kernel (Multiple Advisories)

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Amazon Linux AMI 2: CVE-2021-46981: Security patch for kernel (Multiple Advisories)

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
02/28/2024
Created
06/11/2024
Added
06/11/2024
Modified
01/28/2025

Description

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().

Solution(s)

  • amazon-linux-ami-2-upgrade-bpftool
  • amazon-linux-ami-2-upgrade-bpftool-debuginfo
  • amazon-linux-ami-2-upgrade-kernel
  • amazon-linux-ami-2-upgrade-kernel-debuginfo
  • amazon-linux-ami-2-upgrade-kernel-debuginfo-common-aarch64
  • amazon-linux-ami-2-upgrade-kernel-debuginfo-common-x86_64
  • amazon-linux-ami-2-upgrade-kernel-devel
  • amazon-linux-ami-2-upgrade-kernel-headers
  • amazon-linux-ami-2-upgrade-kernel-tools
  • amazon-linux-ami-2-upgrade-kernel-tools-debuginfo
  • amazon-linux-ami-2-upgrade-kernel-tools-devel
  • amazon-linux-ami-2-upgrade-perf
  • amazon-linux-ami-2-upgrade-perf-debuginfo
  • amazon-linux-ami-2-upgrade-python-perf
  • amazon-linux-ami-2-upgrade-python-perf-debuginfo

References

  • https://attackerkb.com/topics/cve-2021-46981
  • AL2/ALASKERNEL-5.10-2022-002
  • AL2/ALASKERNEL-5.4-2022-004
  • CVE - 2021-46981
  • 查看数 731
  • 已创建
  • 最后回复

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