CVE-2024-53166

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> block, bfq: fix bfqq uaf in bfq_limit_depth()<br /> <br /> Set new allocated bfqq to bic or remove freed bfqq from bic are both<br /> protected by bfqd-&gt;lock, however bfq_limit_depth() is deferencing bfqq<br /> from bic without the lock, this can lead to UAF if the io_context is<br /> shared by multiple tasks.<br /> <br /> For example, test bfq with io_uring can trigger following UAF in v6.6:<br /> <br /> ==================================================================<br /> BUG: KASAN: slab-use-after-free in bfqq_group+0x15/0x50<br /> <br /> Call Trace:<br /> <br /> dump_stack_lvl+0x47/0x80<br /> print_address_description.constprop.0+0x66/0x300<br /> print_report+0x3e/0x70<br /> kasan_report+0xb4/0xf0<br /> bfqq_group+0x15/0x50<br /> bfqq_request_over_limit+0x130/0x9a0<br /> bfq_limit_depth+0x1b5/0x480<br /> __blk_mq_alloc_requests+0x2b5/0xa00<br /> blk_mq_get_new_requests+0x11d/0x1d0<br /> blk_mq_submit_bio+0x286/0xb00<br /> submit_bio_noacct_nocheck+0x331/0x400<br /> __block_write_full_folio+0x3d0/0x640<br /> writepage_cb+0x3b/0xc0<br /> write_cache_pages+0x254/0x6c0<br /> write_cache_pages+0x254/0x6c0<br /> do_writepages+0x192/0x310<br /> filemap_fdatawrite_wbc+0x95/0xc0<br /> __filemap_fdatawrite_range+0x99/0xd0<br /> filemap_write_and_wait_range.part.0+0x4d/0xa0<br /> blkdev_read_iter+0xef/0x1e0<br /> io_read+0x1b6/0x8a0<br /> io_issue_sqe+0x87/0x300<br /> io_wq_submit_work+0xeb/0x390<br /> io_worker_handle_work+0x24d/0x550<br /> io_wq_worker+0x27f/0x6c0<br /> ret_from_fork_asm+0x1b/0x30<br /> <br /> <br /> Allocated by task 808602:<br /> kasan_save_stack+0x1e/0x40<br /> kasan_set_track+0x21/0x30<br /> __kasan_slab_alloc+0x83/0x90<br /> kmem_cache_alloc_node+0x1b1/0x6d0<br /> bfq_get_queue+0x138/0xfa0<br /> bfq_get_bfqq_handle_split+0xe3/0x2c0<br /> bfq_init_rq+0x196/0xbb0<br /> bfq_insert_request.isra.0+0xb5/0x480<br /> bfq_insert_requests+0x156/0x180<br /> blk_mq_insert_request+0x15d/0x440<br /> blk_mq_submit_bio+0x8a4/0xb00<br /> submit_bio_noacct_nocheck+0x331/0x400<br /> __blkdev_direct_IO_async+0x2dd/0x330<br /> blkdev_write_iter+0x39a/0x450<br /> io_write+0x22a/0x840<br /> io_issue_sqe+0x87/0x300<br /> io_wq_submit_work+0xeb/0x390<br /> io_worker_handle_work+0x24d/0x550<br /> io_wq_worker+0x27f/0x6c0<br /> ret_from_fork+0x2d/0x50<br /> ret_from_fork_asm+0x1b/0x30<br /> <br /> Freed by task 808589:<br /> kasan_save_stack+0x1e/0x40<br /> kasan_set_track+0x21/0x30<br /> kasan_save_free_info+0x27/0x40<br /> __kasan_slab_free+0x126/0x1b0<br /> kmem_cache_free+0x10c/0x750<br /> bfq_put_queue+0x2dd/0x770<br /> __bfq_insert_request.isra.0+0x155/0x7a0<br /> bfq_insert_request.isra.0+0x122/0x480<br /> bfq_insert_requests+0x156/0x180<br /> blk_mq_dispatch_plug_list+0x528/0x7e0<br /> blk_mq_flush_plug_list.part.0+0xe5/0x590<br /> __blk_flush_plug+0x3b/0x90<br /> blk_finish_plug+0x40/0x60<br /> do_writepages+0x19d/0x310<br /> filemap_fdatawrite_wbc+0x95/0xc0<br /> __filemap_fdatawrite_range+0x99/0xd0<br /> filemap_write_and_wait_range.part.0+0x4d/0xa0<br /> blkdev_read_iter+0xef/0x1e0<br /> io_read+0x1b6/0x8a0<br /> io_issue_sqe+0x87/0x300<br /> io_wq_submit_work+0xeb/0x390<br /> io_worker_handle_work+0x24d/0x550<br /> io_wq_worker+0x27f/0x6c0<br /> ret_from_fork+0x2d/0x50<br /> ret_from_fork_asm+0x1b/0x30<br /> <br /> Fix the problem by protecting bic_to_bfqq() with bfqd-&gt;lock.