linux-cve-announce - CVE-2024-53166: block, bfq: fix bfqq uaf in bfq_limit

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Message-ID: <2024122714-CVE-2024-53166-8beb@gregkh>
Date: Fri, 27 Dec 2024 14:52:12 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-53166: block, bfq: fix bfqq uaf in bfq_limit_depth()

Description
===========

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

block, bfq: fix bfqq uaf in bfq_limit_depth()

Set new allocated bfqq to bic or remove freed bfqq from bic are both
protected by bfqd->lock, however bfq_limit_depth() is deferencing bfqq
from bic without the lock, this can lead to UAF if the io_context is
shared by multiple tasks.

For example, test bfq with io_uring can trigger following UAF in v6.6:

==================================================================
BUG: KASAN: slab-use-after-free in bfqq_group+0x15/0x50

Call Trace:
 <TASK>
 dump_stack_lvl+0x47/0x80
 print_address_description.constprop.0+0x66/0x300
 print_report+0x3e/0x70
 kasan_report+0xb4/0xf0
 bfqq_group+0x15/0x50
 bfqq_request_over_limit+0x130/0x9a0
 bfq_limit_depth+0x1b5/0x480
 __blk_mq_alloc_requests+0x2b5/0xa00
 blk_mq_get_new_requests+0x11d/0x1d0
 blk_mq_submit_bio+0x286/0xb00
 submit_bio_noacct_nocheck+0x331/0x400
 __block_write_full_folio+0x3d0/0x640
 writepage_cb+0x3b/0xc0
 write_cache_pages+0x254/0x6c0
 write_cache_pages+0x254/0x6c0
 do_writepages+0x192/0x310
 filemap_fdatawrite_wbc+0x95/0xc0
 __filemap_fdatawrite_range+0x99/0xd0
 filemap_write_and_wait_range.part.0+0x4d/0xa0
 blkdev_read_iter+0xef/0x1e0
 io_read+0x1b6/0x8a0
 io_issue_sqe+0x87/0x300
 io_wq_submit_work+0xeb/0x390
 io_worker_handle_work+0x24d/0x550
 io_wq_worker+0x27f/0x6c0
 ret_from_fork_asm+0x1b/0x30
 </TASK>

Allocated by task 808602:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 __kasan_slab_alloc+0x83/0x90
 kmem_cache_alloc_node+0x1b1/0x6d0
 bfq_get_queue+0x138/0xfa0
 bfq_get_bfqq_handle_split+0xe3/0x2c0
 bfq_init_rq+0x196/0xbb0
 bfq_insert_request.isra.0+0xb5/0x480
 bfq_insert_requests+0x156/0x180
 blk_mq_insert_request+0x15d/0x440
 blk_mq_submit_bio+0x8a4/0xb00
 submit_bio_noacct_nocheck+0x331/0x400
 __blkdev_direct_IO_async+0x2dd/0x330
 blkdev_write_iter+0x39a/0x450
 io_write+0x22a/0x840
 io_issue_sqe+0x87/0x300
 io_wq_submit_work+0xeb/0x390
 io_worker_handle_work+0x24d/0x550
 io_wq_worker+0x27f/0x6c0
 ret_from_fork+0x2d/0x50
 ret_from_fork_asm+0x1b/0x30

Freed by task 808589:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 kasan_save_free_info+0x27/0x40
 __kasan_slab_free+0x126/0x1b0
 kmem_cache_free+0x10c/0x750
 bfq_put_queue+0x2dd/0x770
 __bfq_insert_request.isra.0+0x155/0x7a0
 bfq_insert_request.isra.0+0x122/0x480
 bfq_insert_requests+0x156/0x180
 blk_mq_dispatch_plug_list+0x528/0x7e0
 blk_mq_flush_plug_list.part.0+0xe5/0x590
 __blk_flush_plug+0x3b/0x90
 blk_finish_plug+0x40/0x60
 do_writepages+0x19d/0x310
 filemap_fdatawrite_wbc+0x95/0xc0
 __filemap_fdatawrite_range+0x99/0xd0
 filemap_write_and_wait_range.part.0+0x4d/0xa0
 blkdev_read_iter+0xef/0x1e0
 io_read+0x1b6/0x8a0
 io_issue_sqe+0x87/0x300
 io_wq_submit_work+0xeb/0x390
 io_worker_handle_work+0x24d/0x550
 io_wq_worker+0x27f/0x6c0
 ret_from_fork+0x2d/0x50
 ret_from_fork_asm+0x1b/0x30

Fix the problem by protecting bic_to_bfqq() with bfqd->lock.

The Linux kernel CVE team has assigned CVE-2024-53166 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.17 with commit 76f1df88bbc2f984eb0418cc90de0a8384e63604 and fixed in 6.6.64 with commit 906cdbdd3b018ff69cc830173bce277a847d4fdc
	Issue introduced in 5.17 with commit 76f1df88bbc2f984eb0418cc90de0a8384e63604 and fixed in 6.11.11 with commit dcaa738afde55085ac6056252e319479cf23cde2
	Issue introduced in 5.17 with commit 76f1df88bbc2f984eb0418cc90de0a8384e63604 and fixed in 6.12.2 with commit 01a853faaeaf3379ccf358ade582b1d28752126e
	Issue introduced in 5.17 with commit 76f1df88bbc2f984eb0418cc90de0a8384e63604 and fixed in 6.13-rc1 with commit e8b8344de3980709080d86c157d24e7de07d70ad

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-2024-53166
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:
	block/bfq-iosched.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/906cdbdd3b018ff69cc830173bce277a847d4fdc
	https://git.kernel.org/stable/c/dcaa738afde55085ac6056252e319479cf23cde2
	https://git.kernel.org/stable/c/01a853faaeaf3379ccf358ade582b1d28752126e
	https://git.kernel.org/stable/c/e8b8344de3980709080d86c157d24e7de07d70ad