| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-56758: btrfs: check folio mapping after unlock in relocate_one_folio() |
| |
| Description |
| =========== |
| |
| 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: |
| <TASK> |
| ? __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 |
| </TASK> |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2024-56758 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.1.54 with commit 08daa38ca212d87f77beae839bc9be71079c7abf and fixed in 6.1.141 with commit 36679fab54fa7bcffafd469e2c474c1fc4beaee0 |
| Issue introduced in 6.6 with commit e7f1326cc24e22b38afc3acd328480a1183f9e79 and fixed in 6.6.93 with commit c7b1bd52a031ad0144d42eef0ba8471ce75122dd |
| Issue introduced in 6.6 with commit e7f1326cc24e22b38afc3acd328480a1183f9e79 and fixed in 6.12.8 with commit d508e56270389b3a16f5b3cf247f4eb1bbad1578 |
| Issue introduced in 6.6 with commit e7f1326cc24e22b38afc3acd328480a1183f9e79 and fixed in 6.13 with commit 3e74859ee35edc33a022c3f3971df066ea0ca6b9 |
| Issue introduced in 6.5.4 with commit 9d1e020ed9649cf140fcfafd052cfdcce9e9d67d |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-56758 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/btrfs/relocation.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/36679fab54fa7bcffafd469e2c474c1fc4beaee0 |
| https://git.kernel.org/stable/c/c7b1bd52a031ad0144d42eef0ba8471ce75122dd |
| https://git.kernel.org/stable/c/d508e56270389b3a16f5b3cf247f4eb1bbad1578 |
| https://git.kernel.org/stable/c/3e74859ee35edc33a022c3f3971df066ea0ca6b9 |
