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CVE-2021-47082— tun: avoid double free in tun_free_netdev

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于tun_free_netdev 中存在双重释放。

CVSS 7.8 · High EPSS 0.25% · P15

Possible ATT&CK Techniques 1 AI

T1211 · Exploitation for Stealth

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 662ca437e714caaab855b12415d6ffd815985bc0< 8eb43d635950e27c29f1e9e49a23b31637f37757 affected
662ca437e714caaab855b12415d6ffd815985bc0< 0c0e566f0387490d16f166808c72e9c772027681 affected
662ca437e714caaab855b12415d6ffd815985bc0< a01a4e9f5dc93335c716fa4023b1901956e8c904 affected
662ca437e714caaab855b12415d6ffd815985bc0< 3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5 affected
662ca437e714caaab855b12415d6ffd815985bc0< 158b515f703e75e7d68289bf4d98c664e1d632df affected
a81a02460bdf054ca0c60c5aed29941f7134092d affected
6fc265f7a86d81e052508d03da555188f5882c3e affected
3.10.16< 3.11 affected
… +8 more rows
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I. Basic Information for CVE-2021-47082

Vulnerability Information
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Vulnerability Title
tun: avoid double free in tun_free_netdev
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: tun: avoid double free in tun_free_netdev Avoid double free in tun_free_netdev() by moving the dev->tstats and tun->security allocs to a new ndo_init routine (tun_net_init()) that will be called by register_netdevice(). ndo_init is paired with the desctructor (tun_free_netdev()), so if there's an error in register_netdevice() the destructor will handle the frees. BUG: KASAN: double-free or invalid-free in selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605 CPU: 0 PID: 25750 Comm: syz-executor416 Not tainted 5.16.0-rc2-syzk #1 Hardware name: Red Hat KVM, BIOS Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106 print_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:247 kasan_report_invalid_free+0x55/0x80 mm/kasan/report.c:372 ____kasan_slab_free mm/kasan/common.c:346 [inline] __kasan_slab_free+0x107/0x120 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:1723 [inline] slab_free_freelist_hook mm/slub.c:1749 [inline] slab_free mm/slub.c:3513 [inline] kfree+0xac/0x2d0 mm/slub.c:4561 selinux_tun_dev_free_security+0x1a/0x20 security/selinux/hooks.c:5605 security_tun_dev_free_security+0x4f/0x90 security/security.c:2342 tun_free_netdev+0xe6/0x150 drivers/net/tun.c:2215 netdev_run_todo+0x4df/0x840 net/core/dev.c:10627 rtnl_unlock+0x13/0x20 net/core/rtnetlink.c:112 __tun_chr_ioctl+0x80c/0x2870 drivers/net/tun.c:3302 tun_chr_ioctl+0x2f/0x40 drivers/net/tun.c:3311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x19d/0x220 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于tun_free_netdev 中存在双重释放。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 662ca437e714caaab855b12415d6ffd815985bc0 ~ 8eb43d635950e27c29f1e9e49a23b31637f37757 -
Linux Linux 3.12 -

II. Public POCs for CVE-2021-47082

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III. Intelligence Information for CVE-2021-47082

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Other References for CVE-2021-47082 (5)

Same Patch Batch · Linux · 2024-03-04 · 26 CVEs total

CVE-2021-47107 9.8 CRITICAL NFSD: Fix READDIR buffer overflow
CVE-2021-47103 9.8 CRITICAL inet: fully convert sk->sk_rx_dst to RCU rules
CVE-2021-47087 7.8 HIGH tee: optee: Fix incorrect page free bug
CVE-2021-47106 7.8 HIGH netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy()
CVE-2021-47094 7.8 HIGH KVM: x86/mmu: Don't advance iterator after restart due to yielding
CVE-2021-47099 7.8 HIGH veth: ensure skb entering GRO are not cloned.
CVE-2021-47083 7.1 HIGH pinctrl: mediatek: fix global-out-of-bounds issue
CVE-2021-47102 7.1 HIGH net: marvell: prestera: fix incorrect structure access
CVE-2021-47096 ALSA: rawmidi - fix the uninitalized user_pversion
CVE-2021-47108 drm/mediatek: hdmi: Perform NULL pointer check for mtk_hdmi_conf
CVE-2021-47105 ice: xsk: return xsk buffers back to pool when cleaning the ring
CVE-2021-47104 IB/qib: Fix memory leak in qib_user_sdma_queue_pkts()
CVE-2021-47101 asix: fix uninit-value in asix_mdio_read()
CVE-2021-47100 ipmi: Fix UAF when uninstall ipmi_si and ipmi_msghandler module
CVE-2021-47098 hwmon: (lm90) Prevent integer overflow/underflow in hysteresis calculations
CVE-2021-47097 Input: elantech - fix stack out of bound access in elantech_change_report_id()
CVE-2024-26622 tomoyo: fix UAF write bug in tomoyo_write_control()
CVE-2021-47095 ipmi: ssif: initialize ssif_info->client early
CVE-2021-47093 platform/x86: intel_pmc_core: fix memleak on registration failure
CVE-2021-47092 KVM: VMX: Always clear vmx->fail on emulation_required

Showing top 20 of 26 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47082

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