CVE-2021-47256

mm/memory-failure: make sure wait for page writeback in memory_failure

State: Published
Severity: Not scored
Published: May 21, 2024
Updated: May 11, 2026
Reserved: Apr 10, 2024

Description

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before d05267fd27a5c4f54e06daefa3035995d765ca0cAffected 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 6d210d547adc2218ef8b5bcf23518c5f2f1fd872Affected 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 566345aaabac853aa866f53a219c4b02a6beb527Affected 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 9e379da727a7a031be9b877cde7b9c34a0fb8306Affected 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 28788dc5c70597395b6b451dae4549bbaa8e2c56Affected 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before e8675d291ac007e1c636870db880f837a9ea112aAffected
LinuxLinux	3.16Affected before 3.16Not affected 4.14.238 through 4.14.Not affected 4.19.196 through 4.19.Not affected 5.4.128 through 5.4.Not affected 5.10.46 through 5.10.Not affected 5.12.13 through 5.12.*Not affected 5.13 and laterNot affected

Product

Versions

LinuxLinux

0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before d05267fd27a5c4f54e06daefa3035995d765ca0cAffected
0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 6d210d547adc2218ef8b5bcf23518c5f2f1fd872Affected
0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 566345aaabac853aa866f53a219c4b02a6beb527Affected
0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 9e379da727a7a031be9b877cde7b9c34a0fb8306Affected
0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before 28788dc5c70597395b6b451dae4549bbaa8e2c56Affected
0bc1f8b0682caa39f45ce1e0228ebf43acb46111 to before e8675d291ac007e1c636870db880f837a9ea112aAffected

LinuxLinux

3.16Affected
before 3.16Not affected
4.14.238 through 4.14.*Not affected
4.19.196 through 4.19.*Not affected
5.4.128 through 5.4.*Not affected
5.10.46 through 5.10.*Not affected
5.12.13 through 5.12.*Not affected
5.13 and laterNot affected

References

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