| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-56582: btrfs: fix use-after-free in btrfs_encoded_read_endio() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| btrfs: fix use-after-free in btrfs_encoded_read_endio() |
| |
| Shinichiro reported the following use-after free that sometimes is |
| happening in our CI system when running fstests' btrfs/284 on a TCMU |
| runner device: |
| |
| BUG: KASAN: slab-use-after-free in lock_release+0x708/0x780 |
| Read of size 8 at addr ffff888106a83f18 by task kworker/u80:6/219 |
| |
| CPU: 8 UID: 0 PID: 219 Comm: kworker/u80:6 Not tainted 6.12.0-rc6-kts+ #15 |
| Hardware name: Supermicro Super Server/X11SPi-TF, BIOS 3.3 02/21/2020 |
| Workqueue: btrfs-endio btrfs_end_bio_work [btrfs] |
| Call Trace: |
| <TASK> |
| dump_stack_lvl+0x6e/0xa0 |
| ? lock_release+0x708/0x780 |
| print_report+0x174/0x505 |
| ? lock_release+0x708/0x780 |
| ? __virt_addr_valid+0x224/0x410 |
| ? lock_release+0x708/0x780 |
| kasan_report+0xda/0x1b0 |
| ? lock_release+0x708/0x780 |
| ? __wake_up+0x44/0x60 |
| lock_release+0x708/0x780 |
| ? __pfx_lock_release+0x10/0x10 |
| ? __pfx_do_raw_spin_lock+0x10/0x10 |
| ? lock_is_held_type+0x9a/0x110 |
| _raw_spin_unlock_irqrestore+0x1f/0x60 |
| __wake_up+0x44/0x60 |
| btrfs_encoded_read_endio+0x14b/0x190 [btrfs] |
| btrfs_check_read_bio+0x8d9/0x1360 [btrfs] |
| ? lock_release+0x1b0/0x780 |
| ? trace_lock_acquire+0x12f/0x1a0 |
| ? __pfx_btrfs_check_read_bio+0x10/0x10 [btrfs] |
| ? process_one_work+0x7e3/0x1460 |
| ? lock_acquire+0x31/0xc0 |
| ? process_one_work+0x7e3/0x1460 |
| process_one_work+0x85c/0x1460 |
| ? __pfx_process_one_work+0x10/0x10 |
| ? assign_work+0x16c/0x240 |
| worker_thread+0x5e6/0xfc0 |
| ? __pfx_worker_thread+0x10/0x10 |
| kthread+0x2c3/0x3a0 |
| ? __pfx_kthread+0x10/0x10 |
| ret_from_fork+0x31/0x70 |
| ? __pfx_kthread+0x10/0x10 |
| ret_from_fork_asm+0x1a/0x30 |
| </TASK> |
| |
| Allocated by task 3661: |
| kasan_save_stack+0x30/0x50 |
| kasan_save_track+0x14/0x30 |
| __kasan_kmalloc+0xaa/0xb0 |
| btrfs_encoded_read_regular_fill_pages+0x16c/0x6d0 [btrfs] |
| send_extent_data+0xf0f/0x24a0 [btrfs] |
| process_extent+0x48a/0x1830 [btrfs] |
| changed_cb+0x178b/0x2ea0 [btrfs] |
| btrfs_ioctl_send+0x3bf9/0x5c20 [btrfs] |
| _btrfs_ioctl_send+0x117/0x330 [btrfs] |
| btrfs_ioctl+0x184a/0x60a0 [btrfs] |
| __x64_sys_ioctl+0x12e/0x1a0 |
| do_syscall_64+0x95/0x180 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| Freed by task 3661: |
| kasan_save_stack+0x30/0x50 |
| kasan_save_track+0x14/0x30 |
| kasan_save_free_info+0x3b/0x70 |
| __kasan_slab_free+0x4f/0x70 |
| kfree+0x143/0x490 |
| btrfs_encoded_read_regular_fill_pages+0x531/0x6d0 [btrfs] |
| send_extent_data+0xf0f/0x24a0 [btrfs] |
| process_extent+0x48a/0x1830 [btrfs] |
| changed_cb+0x178b/0x2ea0 [btrfs] |
| btrfs_ioctl_send+0x3bf9/0x5c20 [btrfs] |
| _btrfs_ioctl_send+0x117/0x330 [btrfs] |
| btrfs_ioctl+0x184a/0x60a0 [btrfs] |
| __x64_sys_ioctl+0x12e/0x1a0 |
| do_syscall_64+0x95/0x180 |
| entry_SYSCALL_64_after_hwframe+0x76/0x7e |
| |
| The buggy address belongs to the object at ffff888106a83f00 |
| which belongs to the cache kmalloc-rnd-07-96 of size 96 |
| The buggy address is located 24 bytes inside of |
| freed 96-byte region [ffff888106a83f00, ffff888106a83f60) |
| |
| The buggy address belongs to the physical page: |
| page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888106a83800 pfn:0x106a83 |
| flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff) |
| page_type: f5(slab) |
| raw: 0017ffffc0000000 ffff888100053680 ffffea0004917200 0000000000000004 |
| raw: ffff888106a83800 0000000080200019 00000001f5000000 0000000000000000 |
| page dumped because: kasan: bad access detected |
| |
| Memory state around the buggy address: |
| ffff888106a83e00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc |
| ffff888106a83e80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc |
| >ffff888106a83f00: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc |
| ^ |
| ffff888106a83f80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc |
| ffff888106a84000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| ================================================================== |
| |
| Further analyzing the trace and the crash dump's vmcore file shows that |
| the wake_up() call in btrfs_encoded_read_endio() is calling wake_up() on |
| the wait_queue that is in the private data passed to the end_io handler. |
| |
| Commit 4ff47df40447 ("btrfs: move priv off stack in |
| btrfs_encoded_read_regular_fill_pages()") moved 'struct |
| btrfs_encoded_read_private' off the stack. |
| |
| Before that commit one can see a corruption of the private data when |
| analyzing the vmcore after a crash: |
| |
| *(struct btrfs_encoded_read_private *)0xffff88815626eec8 = { |
| .wait = (wait_queue_head_t){ |
| .lock = (spinlock_t){ |
| .rlock = (struct raw_spinlock){ |
| .raw_lock = (arch_spinlock_t){ |
| .val = (atomic_t){ |
| .counter = (int)-2005885696, |
| }, |
| .locked = (u8)0, |
| .pending = (u8)157, |
| .locked_pending = (u16)40192, |
| .tail = (u16)34928, |
| }, |
| .magic = (unsigned int)536325682, |
| .owner_cpu = (unsigned int)29, |
| .owner = (void *)__SCT__tp_func_btrfs_transaction_commit+0x0 = 0x0, |
| .dep_map = (struct lockdep_map){ |
| .key = (struct lock_class_key *)0xffff8881575a3b6c, |
| .class_cache = (struct lock_class *[2]){ 0xffff8882a71985c0, 0xffffea00066f5d40 }, |
| .name = (const char *)0xffff88815626f100 = "", |
| .wait_type_outer = (u8)37, |
| .wait_type_inner = (u8)178, |
| .lock_type = (u8)154, |
| }, |
| }, |
| .__padding = (u8 [24]){ 0, 157, 112, 136, 50, 174, 247, 31, 29 }, |
| .dep_map = (struct lockdep_map){ |
| .key = (struct lock_class_key *)0xffff8881575a3b6c, |
| .class_cache = (struct lock_class *[2]){ 0xffff8882a71985c0, 0xffffea00066f5d40 }, |
| .name = (const char *)0xffff88815626f100 = "", |
| .wait_type_outer = (u8)37, |
| .wait_type_inner = (u8)178, |
| .lock_type = (u8)154, |
| }, |
| }, |
| .head = (struct list_head){ |
| .next = (struct list_head *)0x112cca, |
| .prev = (struct list_head *)0x47, |
| }, |
| }, |
| .pending = (atomic_t){ |
| .counter = (int)-1491499288, |
| }, |
| .status = (blk_status_t)130, |
| } |
| |
| Here we can see several indicators of in-memory data corruption, e.g. the |
| large negative atomic values of ->pending or |
| ->wait->lock->rlock->raw_lock->val, as well as the bogus spinlock magic |
| 0x1ff7ae32 (decimal 536325682 above) instead of 0xdead4ead or the bogus |
| pointer values for ->wait->head. |
| |
| To fix this, change atomic_dec_return() to atomic_dec_and_test() to fix the |
| corruption, as atomic_dec_return() is defined as two instructions on |
| x86_64, whereas atomic_dec_and_test() is defined as a single atomic |
| operation. This can lead to a situation where counter value is already |
| decremented but the if statement in btrfs_encoded_read_endio() is not |
| completely processed, i.e. the 0 test has not completed. If another thread |
| continues executing btrfs_encoded_read_regular_fill_pages() the |
| atomic_dec_return() there can see an already updated ->pending counter and |
| continues by freeing the private data. Continuing in the endio handler the |
| test for 0 succeeds and the wait_queue is woken up, resulting in a |
| use-after-free. |
| |
| The Linux kernel CVE team has assigned CVE-2024-56582 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.18 with commit 1881fba89bd5dcd364d2e1bf561912a90a11c21a and fixed in 6.1.124 with commit a40de0330af4fb7bc6b354250c24f294f8b826a0 |
| Issue introduced in 5.18 with commit 1881fba89bd5dcd364d2e1bf561912a90a11c21a and fixed in 6.6.70 with commit 6228f13f1996a4feb9b601d6644bf0bfe03671dd |
| Issue introduced in 5.18 with commit 1881fba89bd5dcd364d2e1bf561912a90a11c21a and fixed in 6.12.4 with commit f8a5129e4a9fc3f6aa3f137513253b51b31b94d4 |
| Issue introduced in 5.18 with commit 1881fba89bd5dcd364d2e1bf561912a90a11c21a and fixed in 6.13 with commit 05b36b04d74a517d6675bf2f90829ff1ac7e28dc |
| |
| 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-2024-56582 |
| 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/inode.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/a40de0330af4fb7bc6b354250c24f294f8b826a0 |
| https://git.kernel.org/stable/c/6228f13f1996a4feb9b601d6644bf0bfe03671dd |
| https://git.kernel.org/stable/c/f8a5129e4a9fc3f6aa3f137513253b51b31b94d4 |
| https://git.kernel.org/stable/c/05b36b04d74a517d6675bf2f90829ff1ac7e28dc |
