| Summary: |
VUL-0: CVE-2021-47256: kernel: mm/memory-failure: make sure wait for page writeback in memory_failure |
| Product: |
[Novell Products] SUSE Security Incidents
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Reporter: |
SMASH SMASH <smash_bz> |
| Component: |
Incidents | Assignee: |
Oscar Salvador <osalvador> |
| Status: |
NEW
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QA Contact: |
Security Team bot <security-team> |
| Severity: |
Normal
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| Priority: |
P3 - Medium
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CC: |
andrea.mattiazzo, mhocko, osalvador
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| Version: |
unspecified | Flags: |
mhocko:
needinfo?
(osalvador)
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| Target Milestone: |
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| Hardware: |
Other | |
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| OS: |
Other | |
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| URL: |
https://smash.suse.de/issue/406885/
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| Whiteboard: |
CVSSv3.1:SUSE:CVE-2021-47256:5.5:(AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) |
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Found By:
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Security Response Team
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Services Priority:
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Business Priority:
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Blocker:
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Marketing QA Status:
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IT Deployment:
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In the Linux kernel, the following vulnerability has been resolved: mm/memory-failure: make sure wait for page writeback in memory_failure Our syzkaller trigger the "BUG_ON(!list_empty(&inode->i_wb_list))" in clear_inode: kernel BUG at fs/inode.c:519! Internal error: Oops - BUG: 0 [#1] SMP Modules linked in: Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7) CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95 Hardware name: linux,dummy-virt (DT) pstate: 80000005 (Nzcv daif -PAN -UAO) pc : clear_inode+0x280/0x2a8 lr : clear_inode+0x280/0x2a8 Call trace: clear_inode+0x280/0x2a8 ext4_clear_inode+0x38/0xe8 ext4_free_inode+0x130/0xc68 ext4_evict_inode+0xb20/0xcb8 evict+0x1a8/0x3c0 iput+0x344/0x460 do_unlinkat+0x260/0x410 __arm64_sys_unlinkat+0x6c/0xc0 el0_svc_common+0xdc/0x3b0 el0_svc_handler+0xf8/0x160 el0_svc+0x10/0x218 Kernel panic - not syncing: Fatal exception A crash dump of this problem show that someone called __munlock_pagevec to clear page LRU without lock_page: do_mmap -> mmap_region -> do_munmap -> munlock_vma_pages_range -> __munlock_pagevec. As a result memory_failure will call identify_page_state without wait_on_page_writeback. And after truncate_error_page clear the mapping of this page. end_page_writeback won't call sb_clear_inode_writeback to clear inode->i_wb_list. That will trigger BUG_ON in clear_inode! Fix it by checking PageWriteback too to help determine should we skip wait_on_page_writeback. References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47256 https://www.cve.org/CVERecord?id=CVE-2021-47256 https://git.kernel.org/stable/c/28788dc5c70597395b6b451dae4549bbaa8e2c56 https://git.kernel.org/stable/c/566345aaabac853aa866f53a219c4b02a6beb527 https://git.kernel.org/stable/c/6d210d547adc2218ef8b5bcf23518c5f2f1fd872 https://git.kernel.org/stable/c/9e379da727a7a031be9b877cde7b9c34a0fb8306 https://git.kernel.org/stable/c/d05267fd27a5c4f54e06daefa3035995d765ca0c https://git.kernel.org/stable/c/e8675d291ac007e1c636870db880f837a9ea112a https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2021/CVE-2021-47256.mbox