In the Linux kernel, the following vulnerability has been resolved:
af_unix: Drop oob_skb ref before purging queue in GC.
syzbot reported another task hung in __unix_gc(). [0]
The current while loop assumes that all of the left candidates have oob_skb and calling kfree_skb(oob_skb) releases the remaining candidates.
However, I missed a case that oob_skb has self-referencing fd and another fd and the latter sk is placed before the former in the candidate list. Then, the while loop never proceeds, resulting the task hung.
__unix_gc() has the same loop just before purging the collected skb, so we can call kfree_skb(oob_skb) there and let __skb_queue_purge() release all inflight sockets.
[0]: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 2784 Comm: kworker/u4:8 Not tainted 6.8.0-rc4-syzkaller-01028-g71b605d32017 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Workqueue: events_unbound __unix_gc RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:200 Code: 89 fb e8 23 00 00 00 48 8b 3d 84 f5 1a 0c 48 89 de 5b e9 43 26 57 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0d 90 52 70 7e 65 8b 15 91 52 70 RSP: 0018:ffffc9000a17fa78 EFLAGS: 00000287 RAX: ffffffff8a0a6108 RBX: ffff88802b6c2640 RCX: ffff88802c0b3b80 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 RBP: ffffc9000a17fbf0 R08: ffffffff89383f1d R09: 1ffff1100ee5ff84 R10: dffffc0000000000 R11: ffffed100ee5ff85 R12: 1ffff110056d84ee R13: ffffc9000a17fae0 R14: 0000000000000000 R15: ffffffff8f47b840 FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffef5687ff8 CR3: 0000000029b34000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <NMI> </NMI> <TASK> __unix_gc+0xe69/0xf40 net/unix/garbage.c:343 process_one_work kernel/workqueue.c:2633 [inline] process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706 worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787 kthread+0x2ef/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242 </TASK>
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-debuginfoUpgrade kernelUpgrade kernel-tools-debuginfoUpgrade bpftoolUpgrade bpftool-debuginfoUpgrade kernel-develUpgrade kernel-toolsUpgrade kernel-debuginfo-common-x86_64Upgrade python-perfUpgrade kernel-livepatch-5.15.152-100.162Upgrade kernel-debuginfo-common-aarch64Upgrade perf-debuginfoUpgrade kernel-headersUpgrade python-perf-debuginfoUpgrade kernel-tools-develUpgrade perf | Aug 28, 2024 | Apr 4, 2024 |
| Debian | — | Upgrade linux | Jul 30, 2024 | Apr 4, 2024 |
| Suse | — | Upgrade kernel-debug-livepatch-develUpgrade kernel-obs-qaUpgrade kernel-devel-rtUpgrade ocfs2-kmp-64kbUpgrade gfs2-kmp-rtUpgrade kernel-rt-develUpgrade cluster-md-kmp-defaultUpgrade kernel-zfcpdumpUpgrade kernel-azure-optionalUpgrade kernel-kvmsmall-vdsoUpgrade dtb-mediatekUpgrade dlm-kmp-64kbUpgrade kernel-default-base-rebuildUpgrade kernel-syms-azureUpgrade ocfs2-kmp-rtUpgrade cluster-md-kmp-azureUpgrade gfs2-kmp-64kbUpgrade kernel-azure-develUpgrade kernel-rtUpgrade kernel-default-vdsoUpgrade kernel-devel-azureUpgrade kernel-azure-livepatch-develUpgrade kernel-kvmsmallUpgrade dtb-alteraUpgrade dtb-freescaleUpgrade kernel-64kbUpgrade kernel-symsUpgrade dtb-caviumUpgrade dtb-lgUpgrade kernel-rt-optionalUpgrade kernel-default-develUpgrade kernel-kvmsmall-develUpgrade kernel-macrosUpgrade kernel-sourceUpgrade cluster-md-kmp-rtUpgrade kernel-source-azureUpgrade kselftests-kmp-64kbUpgrade kernel-rt_debug-develUpgrade dtb-amlogicUpgrade dtb-qcomUpgrade reiserfs-kmp-azureUpgrade kernel-rt-vdsoUpgrade kernel-default-livepatchUpgrade dtb-rockchipUpgrade kernel-default-extraUpgrade kernel-64kb-livepatch-develUpgrade kernel-default-optionalUpgrade dtb-apmUpgrade kernel-azure-vdsoUpgrade dtb-amazonUpgrade dtb-exynosUpgrade kernel-rt-livepatch-develUpgrade dlm-kmp-defaultUpgrade kernel-64kb-extraUpgrade kernel-rt_debug-vdsoUpgrade kernel-kvmsmall-livepatch-develUpgrade kernel-debug-develUpgrade kernel-develUpgrade kernel-64kb-optionalUpgrade dtb-socionextUpgrade dtb-amdUpgrade ocfs2-kmp-azureUpgrade kernel-rt_debug-livepatch-develUpgrade kernel-obs-buildUpgrade kernel-azureUpgrade dtb-appleUpgrade dlm-kmp-rtUpgrade dtb-renesasUpgrade kernel-defaultUpgrade gfs2-kmp-defaultUpgrade dtb-sprdUpgrade reiserfs-kmp-rtUpgrade kernel-rt_debugUpgrade kernel-docsUpgrade kselftests-kmp-azureUpgrade dtb-hisiliconUpgrade dtb-broadcomUpgrade reiserfs-kmp-defaultUpgrade dtb-allwinnerUpgrade kernel-default-livepatch-develUpgrade dtb-xilinxUpgrade gfs2-kmp-azureUpgrade dlm-kmp-azureUpgrade ocfs2-kmp-defaultUpgrade kselftests-kmp-rtUpgrade kernel-source-rtUpgrade kernel-rt-extraUpgrade kernel-default-baseUpgrade kernel-syms-rtUpgrade reiserfs-kmp-64kbUpgrade kernel-source-vanillaUpgrade kernel-docs-htmlUpgrade kernel-debug-vdsoUpgrade kernel-debugUpgrade dtb-nvidiaUpgrade cluster-md-kmp-64kbUpgrade dtb-armUpgrade kselftests-kmp-defaultUpgrade kernel-azure-extraUpgrade dtb-marvellUpgrade kernel-64kb-devel | Jul 23, 2024 | Apr 4, 2024 |
| Ubuntu | — | Upgrade linux-image-awsUpgrade linux-image-oem-20.04bUpgrade linux-image-5.15.0-110-lowlatency-64kUpgrade linux-image-lowlatency-64k-hwe-20.04Upgrade linux-image-aws-lts-22.04Upgrade linux-image-5.15.0-1063-awsUpgrade linux-image-5.15.0-1061-oracleUpgrade linux-image-lowlatencyUpgrade linux-image-5.15.0-1065-azure-fdeUpgrade linux-image-5.15.0-112-genericUpgrade linux-image-lowlatency-hwe-20.04Upgrade linux-image-5.15.0-1058-nvidia-lowlatencyUpgrade linux-image-kvmUpgrade linux-image-gke-5.15Upgrade linux-image-ibmUpgrade linux-image-oem-20.04dUpgrade linux-image-generic-lpaeUpgrade linux-image-nvidia-lowlatencyUpgrade linux-image-5.15.0-1056-ibmUpgrade linux-image-5.15.0-113-generic-64kUpgrade linux-image-raspiUpgrade linux-image-gcpUpgrade linux-image-raspi-nolpaeUpgrade linux-image-5.15.0-113-genericUpgrade linux-image-generic-64k-hwe-20.04Upgrade linux-image-5.15.0-1046-gkeopUpgrade linux-image-5.15.0-110-lowlatencyUpgrade linux-image-5.15.0-1062-gcpUpgrade linux-image-5.15.0-1066-azureUpgrade linux-image-oem-20.04cUpgrade linux-image-gcp-lts-22.04Upgrade linux-image-5.15.0-112-generic-lpaeUpgrade linux-image-gkeopUpgrade linux-image-genericUpgrade linux-image-virtual-hwe-20.04Upgrade linux-image-intelUpgrade linux-image-xilinx-zynqmpUpgrade linux-image-oracle-lts-22.04Upgrade linux-image-lowlatency-64kUpgrade linux-image-azure-lts-22.04Upgrade linux-image-5.15.0-112-generic-64kUpgrade linux-image-5.15.0-113-generic-lpaeUpgrade linux-image-nvidiaUpgrade linux-image-5.15.0-1030-xilinx-zynqmpUpgrade linux-image-gkeUpgrade linux-image-5.15.0-1058-nvidiaUpgrade linux-image-oem-20.04Upgrade linux-image-intel-iotgUpgrade linux-image-5.15.0-1057-ibmUpgrade linux-image-generic-hwe-20.04Upgrade linux-image-gkeop-5.15Upgrade linux-image-5.15.0-1060-gkeUpgrade linux-image-virtualUpgrade linux-image-5.15.0-1060-kvmUpgrade linux-image-5.15.0-1058-intel-iotgUpgrade linux-image-generic-64kUpgrade linux-image-azure-fde-lts-22.04Upgrade linux-image-generic-lpae-hwe-20.04Upgrade linux-image-5.15.0-1058-raspi | Jul 1, 2024 | Apr 4, 2024 |
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