mm, thp: bail out early in collapse_file for writeback page
CVSS score
7.8
EPSS probability
%0.2
Risk score
0.0
Published
2 y ago
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Vulnerability description
DayBreach CVE AI Research
CVE-2021-47492 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.
In the Linux kernel, the following vulnerability has been resolved: mm, thp: bail out early in collapse_file for writeback page Currently collapse_file does not explicitly check PG_writeback, instead, page_has_private and try_to_release_page are used to filter writeback pages. This does not work for xfs with blocksize equal to or larger than pagesize, because in such case xfs has no page->private. This makes collapse_file bail out early for writeback page. Otherwise, xfs end_page_writeback will panic as follows. page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32 aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so" flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback) raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000 page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u)) page->mem_cgroup:ffff0000c3e9a000 ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:1212! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: BUG: Bad page state in process khugepaged pfn:84ef32 xfs(E) page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32 libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ... pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) Call trace: end_page_writeback+0x1c0/0x214 iomap_finish_page_writeback+0x13c/0x204 iomap_finish_ioend+0xe8/0x19c iomap_writepage_end_bio+0x38/0x50 bio_endio+0x168/0x1ec blk_update_request+0x278/0x3f0 blk_mq_end_request+0x34/0x15c virtblk_request_done+0x38/0x74 [virtio_blk] blk_done_softirq+0xc4/0x110 __do_softirq+0x128/0x38c __irq_exit_rcu+0x118/0x150 irq_exit+0x1c/0x30 __handle_domain_irq+0x8c/0xf0 gic_handle_irq+0x84/0x108 el1_irq+0xcc/0x180 arch_cpu_idle+0x18/0x40 default_idle_call+0x4c/0x1a0 cpuidle_idle_call+0x168/0x1e0 do_idle+0xb4/0x104 cpu_startup_entry+0x30/0x9c secondary_start_kernel+0x104/0x180 Code: d4210000 b0006161 910c8021 94013f4d (d4210000) ---[ end trace 4a88c6a074082f8c ]--- Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt
IMPACT: Affected Products and Software
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 7.8 | CVSS V3_1 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | CVE CNA |
| 7.8 | CVSS V31 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD |
| 5.5 | CVSS V31 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-47492 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-47492 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
CVSS Vector Radar Chart
7.8 / 10Vulnerability Scoring Details
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HYama doğrulandı
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