Executive Summary

Informations
Name CVE-2024-56758 First vendor Publication 2025-01-06
Vendor Cve Last vendor Modification 2025-01-07

Security-Database Scoring CVSS v3

Cvss vector : CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Overall CVSS Score 5.5
Base Score 5.5 Environmental Score 5.5
impact SubScore 3.6 Temporal Score 5.5
Exploitabality Sub Score 1.8
 
Attack Vector Local Attack Complexity Low
Privileges Required Low User Interaction None
Scope Unchanged Confidentiality Impact None
Integrity Impact None Availability Impact High
Calculate full CVSS 3.0 Vectors scores

Security-Database Scoring CVSS v2

Cvss vector :
Cvss Base Score N/A Attack Range N/A
Cvss Impact Score N/A Attack Complexity N/A
Cvss Expoit Score N/A Authentication N/A
Calculate full CVSS 2.0 Vectors scores

Detail

In the Linux kernel, the following vulnerability has been resolved:

btrfs: check folio mapping after unlock in relocate_one_folio()

When we call btrfs_read_folio() to bring a folio uptodate, we unlock the folio. The result of that is that a different thread can modify the mapping (like remove it with invalidate) before we call folio_lock(). This results in an invalid page and we need to try again.

In particular, if we are relocating concurrently with aborting a transaction, this can result in a crash like the following:

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 0 P4D 0
Oops: 0000 [#1] SMP
CPU: 76 PID: 1411631 Comm: kworker/u322:5
Workqueue: events_unbound btrfs_reclaim_bgs_work
RIP: 0010:set_page_extent_mapped+0x20/0xb0
RSP: 0018:ffffc900516a7be8 EFLAGS: 00010246
RAX: ffffea009e851d08 RBX: ffffea009e0b1880 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffc900516a7b90 RDI: ffffea009e0b1880
RBP: 0000000003573000 R08: 0000000000000001 R09: ffff88c07fd2f3f0
R10: 0000000000000000 R11: 0000194754b575be R12: 0000000003572000
R13: 0000000003572fff R14: 0000000000100cca R15: 0000000005582fff
FS: 0000000000000000(0000) GS:ffff88c07fd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000407d00f002 CR4: 00000000007706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:

? __die+0x78/0xc0
? page_fault_oops+0x2a8/0x3a0
? __switch_to+0x133/0x530
? wq_worker_running+0xa/0x40
? exc_page_fault+0x63/0x130
? asm_exc_page_fault+0x22/0x30
? set_page_extent_mapped+0x20/0xb0
relocate_file_extent_cluster+0x1a7/0x940
relocate_data_extent+0xaf/0x120
relocate_block_group+0x20f/0x480
btrfs_relocate_block_group+0x152/0x320
btrfs_relocate_chunk+0x3d/0x120
btrfs_reclaim_bgs_work+0x2ae/0x4e0
process_scheduled_works+0x184/0x370
worker_thread+0xc6/0x3e0
? blk_add_timer+0xb0/0xb0
kthread+0xae/0xe0
? flush_tlb_kernel_range+0x90/0x90
ret_from_fork+0x2f/0x40
? flush_tlb_kernel_range+0x90/0x90
ret_from_fork_asm+0x11/0x20

This occurs because cleanup_one_transaction() calls destroy_delalloc_inodes() which calls invalidate_inode_pages2() which takes the folio_lock before setting mapping to NULL. We fail to check this, and subsequently call set_extent_mapping(), which assumes that mapping != NULL (in fact it asserts that in debug mode)

Note that the "fixes" patch here is not the one that introduced the race (the very first iteration of this code from 2009) but a more recent change that made this particular crash happen in practice.

Original Source

Url : http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-56758

CWE : Common Weakness Enumeration

% Id Name
100 % CWE-476 NULL Pointer Dereference

CPE : Common Platform Enumeration

TypeDescriptionCount
Application 8
Os 3672

Sources (Detail)

https://git.kernel.org/stable/c/3e74859ee35edc33a022c3f3971df066ea0ca6b9
https://git.kernel.org/stable/c/d508e56270389b3a16f5b3cf247f4eb1bbad1578
Source Url

Alert History

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0
1
Date Informations
2025-01-08 00:20:34
  • Multiple Updates
2025-01-06 21:20:27
  • First insertion