CVE-2021-47146

Public on

Last Modified: UTC

Description

The CVE Program describes this issue as:

In the Linux kernel, the following vulnerability has been resolved: mld: fix panic in mld_newpack() mld_newpack() doesn't allow to allocate high order page, only order-0 allocation is allowed. If headroom size is too large, a kernel panic could occur in skb_put(). Test commands: ip netns del A ip netns del B ip netns add A ip netns add B ip link add veth0 type veth peer name veth1 ip link set veth0 netns A ip link set veth1 netns B ip netns exec A ip link set lo up ip netns exec A ip link set veth0 up ip netns exec A ip -6 a a 2001:db8:0::1/64 dev veth0 ip netns exec B ip link set lo up ip netns exec B ip link set veth1 up ip netns exec B ip -6 a a 2001:db8:0::2/64 dev veth1 for i in {1..99} do let A=$i-1 ip netns exec A ip link add ip6gre$i type ip6gre \ local 2001:db8:$A::1 remote 2001:db8:$A::2 encaplimit 100 ip netns exec A ip -6 a a 2001:db8:$i::1/64 dev ip6gre$i ip netns exec A ip link set ip6gre$i up ip netns exec B ip link add ip6gre$i type ip6gre \ local 2001:db8:$A::2 remote 2001:db8:$A::1 encaplimit 100 ip netns exec B ip -6 a a 2001:db8:$i::2/64 dev ip6gre$i ip netns exec B ip link set ip6gre$i up done Splat looks like: kernel BUG at net/core/skbuff.c:110! invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI CPU: 0 PID: 7 Comm: kworker/0:1 Not tainted 5.12.0+ #891 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:skb_panic+0x15d/0x15f Code: 92 fe 4c 8b 4c 24 10 53 8b 4d 70 45 89 e0 48 c7 c7 00 ae 79 83 41 57 41 56 41 55 48 8b 54 24 a6 26 f9 ff <0f> 0b 48 8b 6c 24 20 89 34 24 e8 4a 4e 92 fe 8b 34 24 48 c7 c1 20 RSP: 0018:ffff88810091f820 EFLAGS: 00010282 RAX: 0000000000000089 RBX: ffff8881086e9000 RCX: 0000000000000000 RDX: 0000000000000089 RSI: 0000000000000008 RDI: ffffed1020123efb RBP: ffff888005f6eac0 R08: ffffed1022fc0031 R09: ffffed1022fc0031 R10: ffff888117e00187 R11: ffffed1022fc0030 R12: 0000000000000028 R13: ffff888008284eb0 R14: 0000000000000ed8 R15: 0000000000000ec0 FS: 0000000000000000(0000) GS:ffff888117c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8b801c5640 CR3: 0000000033c2c006 CR4: 00000000003706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? ip6_mc_hdr.isra.26.constprop.46+0x12a/0x600 ? ip6_mc_hdr.isra.26.constprop.46+0x12a/0x600 skb_put.cold.104+0x22/0x22 ip6_mc_hdr.isra.26.constprop.46+0x12a/0x600 ? rcu_read_lock_sched_held+0x91/0xc0 mld_newpack+0x398/0x8f0 ? ip6_mc_hdr.isra.26.constprop.46+0x600/0x600 ? lock_contended+0xc40/0xc40 add_grhead.isra.33+0x280/0x380 add_grec+0x5ca/0xff0 ? mld_sendpack+0xf40/0xf40 ? lock_downgrade+0x690/0x690 mld_send_initial_cr.part.34+0xb9/0x180 ipv6_mc_dad_complete+0x15d/0x1b0 addrconf_dad_completed+0x8d2/0xbb0 ? lock_downgrade+0x690/0x690 ? addrconf_rs_timer+0x660/0x660 ? addrconf_dad_work+0x73c/0x10e0 addrconf_dad_work+0x73c/0x10e0 Allowing high order page allocation could fix this problem.

Additional information

  • Bugzilla 2271497: kernel: mld: fix panic in mld_newpack()
  • CWE-99: Improper Control of Resource Identifiers ('Resource Injection')
  • FAQ: Frequently asked questions about CVE-2021-47146

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

5.5

5.5

Attack Vector

Local

Local

Attack Complexity

Low

Low

Privileges Required

Low

Low

User Interaction

None

None

Scope

Unchanged

Unchanged

Confidentiality Impact

None

None

Integrity Impact

None

None

Availability Impact

High

High

CVSS v3 Vector

Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our Red Hat Vulnerability Scanner Certification program.

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