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CVE-2021-46955— openvswitch: fix stack OOB read while fragmenting IPv4 packets

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 IPv4 数据包分段时，会导致越界读取问题。

CVSS 8.2 · High EPSS 0.75% · P53

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 25

VendorProduct Version RangeStatus
Linux Linux 119bbaa6795a4f4aed46994cc7d9ab01989c87e3< b1d7280f9ba1bfdbc3af5bdb82e51f014854f26f affected
d543907a4730400f5c5b684c57cb5bbbfd6136ab< 23e17ec1a5eb53fe39cc34fa5592686d5acd0dac affected
8387fbac8e18e26a60559adc63e0b7067303b0a4< 5a52fa8ad45b5a593ed416adf326538638454ff1 affected
d52e5a7e7ca49457dd31fc8b42fb7c0d58a31221< df9e900de24637be41879e2c50afb713ec4e8b2e affected
d52e5a7e7ca49457dd31fc8b42fb7c0d58a31221< 490ad0a2390442d0a7b8c00972a83dbb09cab142 affected
d52e5a7e7ca49457dd31fc8b42fb7c0d58a31221< a1478374b0bda89b4277a8afd39208271faad4be affected
d52e5a7e7ca49457dd31fc8b42fb7c0d58a31221< d841d3cf5297fde4ce6a41ff35451d0e82917f3e affected
d52e5a7e7ca49457dd31fc8b42fb7c0d58a31221< b3502b04e84ac5349be95fc033c17bd701d2787a affected
… +17 more rows
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I. Basic Information for CVE-2021-46955

Vulnerability Information
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Vulnerability Title
openvswitch: fix stack OOB read while fragmenting IPv4 packets
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix stack OOB read while fragmenting IPv4 packets running openvswitch on kernels built with KASAN, it's possible to see the following splat while testing fragmentation of IPv4 packets: BUG: KASAN: stack-out-of-bounds in ip_do_fragment+0x1b03/0x1f60 Read of size 1 at addr ffff888112fc713c by task handler2/1367 CPU: 0 PID: 1367 Comm: handler2 Not tainted 5.12.0-rc6+ #418 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014 Call Trace: dump_stack+0x92/0xc1 print_address_description.constprop.7+0x1a/0x150 kasan_report.cold.13+0x7f/0x111 ip_do_fragment+0x1b03/0x1f60 ovs_fragment+0x5bf/0x840 [openvswitch] do_execute_actions+0x1bd5/0x2400 [openvswitch] ovs_execute_actions+0xc8/0x3d0 [openvswitch] ovs_packet_cmd_execute+0xa39/0x1150 [openvswitch] genl_family_rcv_msg_doit.isra.15+0x227/0x2d0 genl_rcv_msg+0x287/0x490 netlink_rcv_skb+0x120/0x380 genl_rcv+0x24/0x40 netlink_unicast+0x439/0x630 netlink_sendmsg+0x719/0xbf0 sock_sendmsg+0xe2/0x110 ____sys_sendmsg+0x5ba/0x890 ___sys_sendmsg+0xe9/0x160 __sys_sendmsg+0xd3/0x170 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f957079db07 Code: c3 66 90 41 54 41 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 eb ec ff ff 44 89 e2 48 89 ee 89 df 41 89 c0 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 48 89 44 24 08 e8 24 ed ff ff 48 RSP: 002b:00007f956ce35a50 EFLAGS: 00000293 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000019 RCX: 00007f957079db07 RDX: 0000000000000000 RSI: 00007f956ce35ae0 RDI: 0000000000000019 RBP: 00007f956ce35ae0 R08: 0000000000000000 R09: 00007f9558006730 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f956ce37308 R14: 00007f956ce35f80 R15: 00007f956ce35ae0 The buggy address belongs to the page: page:00000000af2a1d93 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112fc7 flags: 0x17ffffc0000000() raw: 0017ffffc0000000 0000000000000000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected addr ffff888112fc713c is located in stack of task handler2/1367 at offset 180 in frame: ovs_fragment+0x0/0x840 [openvswitch] this frame has 2 objects: [32, 144) 'ovs_dst' [192, 424) 'ovs_rt' Memory state around the buggy address: ffff888112fc7000: f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888112fc7080: 00 f1 f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00 >ffff888112fc7100: 00 00 00 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 ^ ffff888112fc7180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888112fc7200: 00 00 00 00 00 00 f2 f2 f2 00 00 00 00 00 00 00 for IPv4 packets, ovs_fragment() uses a temporary struct dst_entry. Then, in the following call graph: ip_do_fragment() ip_skb_dst_mtu() ip_dst_mtu_maybe_forward() ip_mtu_locked() the pointer to struct dst_entry is used as pointer to struct rtable: this turns the access to struct members like rt_mtu_locked into an OOB read in the stack. Fix this changing the temporary variable used for IPv4 packets in ovs_fragment(), similarly to what is done for IPv6 few lines below.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 IPv4 数据包分段时，会导致越界读取问题。
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 119bbaa6795a4f4aed46994cc7d9ab01989c87e3 ~ b1d7280f9ba1bfdbc3af5bdb82e51f014854f26f -
Linux Linux 4.16 -

II. Public POCs for CVE-2021-46955

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III. Intelligence Information for CVE-2021-46955

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Other References for CVE-2021-46955 (6)

Same Patch Batch · Linux · 2024-02-27 · 67 CVEs total

CVE-2021-46911 9.8 CRITICAL ch_ktls: Fix kernel panic
CVE-2021-46925 7.8 HIGH net/smc: fix kernel panic caused by race of smc_sock
CVE-2021-46963 7.8 HIGH scsi: qla2xxx: Fix crash in qla2xxx_mqueuecommand()
CVE-2021-46929 7.8 HIGH sctp: use call_rcu to free endpoint
CVE-2021-46913 7.8 HIGH netfilter: nftables: clone set element expression template
CVE-2021-46973 7.8 HIGH net: qrtr: Avoid potential use after free in MHI send
CVE-2021-46936 7.8 HIGH net: fix use-after-free in tw_timer_handler
CVE-2021-46933 7.8 HIGH usb: gadget: f_fs: Clear ffs_eventfd in ffs_data_clear.
CVE-2021-46958 7.8 HIGH btrfs: fix race between transaction aborts and fsyncs leading to use-after-free
CVE-2021-46969 7.8 HIGH bus: mhi: core: Fix invalid error returning in mhi_queue
CVE-2021-46922 7.8 HIGH KEYS: trusted: Fix TPM reservation for seal/unseal
CVE-2021-46967 7.8 HIGH vhost-vdpa: fix vm_flags for virtqueue doorbell mapping
CVE-2021-46921 7.8 HIGH locking/qrwlock: Fix ordering in queued_write_lock_slowpath()
CVE-2021-46948 7.5 HIGH sfc: farch: fix TX queue lookup in TX event handling
CVE-2021-46960 7.5 HIGH cifs: Return correct error code from smb2_get_enc_key
CVE-2021-46912 7.3 HIGH net: Make tcp_allowed_congestion_control readonly in non-init netns
CVE-2021-46908 7.1 HIGH bpf: Use correct permission flag for mixed signed bounds arithmetic
CVE-2021-46974 7.1 HIGH bpf: Fix masking negation logic upon negative dst register
CVE-2021-46910 7.0 HIGH ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled
CVE-2021-46952 NFS: fs_context: validate UDP retrans to prevent shift out-of-bounds

Showing top 20 of 67 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-46955

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