CVE-2024-56653: In the Linux kernel, the following vulnerability has been resolved:  Bluetooth: btmtk: avoid UAF in btmtk_process_coredump  hci_devcd_append may lead to the release of the skb, so it cannot be accessed once it is called.  ================================================================== BUG: KASAN: slab-use-after-free in btmtk_process_coredump+0x2a7/0x2d0 [btmtk] Read of size 4 at addr ffff888033cfabb0 by task kworker/0:3/82  CPU: 0 PID: 82 Comm: kworker/0:3 Tainted: G     U             6.6.40-lockdep-03464-g1d8b4eb3060e #1 b0b3c1cc0c842735643fb411799d97921d1f688c Hardware name: Google Yaviks_Ufs/Yaviks_Ufs, BIOS Google_Yaviks_Ufs.15217.552.0 05/07/2024 Workqueue: events btusb_rx_work [btusb] Call Trace:  <TASK>  dump_stack_lvl+0xfd/0x150  print_report+0x131/0x780  kasan_report+0x177/0x1c0  btmtk_process_coredump+0x2a7/0x2d0 [btmtk 03edd567dd71a65958807c95a65db31d433e1d01]  btusb_recv_acl_mtk+0x11c/0x1a0 [btusb 675430d1e87c4f24d0c1f80efe600757a0f32bec]  btusb_rx_work+0x9e/0xe0 [btusb 675430d1e87c4f24d0c1f80efe600757a0f32bec]  worker_thread+0xe44/0x2cc0  kthread+0x2ff/0x3a0  ret_from_fork+0x51/0x80  ret_from_fork_asm+0x1b/0x30  </TASK>  Allocated by task 82:  stack_trace_save+0xdc/0x190  kasan_set_track+0x4e/0x80  __kasan_slab_alloc+0x4e/0x60  kmem_cache_alloc+0x19f/0x360  skb_clone+0x132/0xf70  btusb_recv_acl_mtk+0x104/0x1a0 [btusb]  btusb_rx_work+0x9e/0xe0 [btusb]  worker_thread+0xe44/0x2cc0  kthread+0x2ff/0x3a0  ret_from_fork+0x51/0x80  ret_from_fork_asm+0x1b/0x30  Freed by task 1733:  stack_trace_save+0xdc/0x190  kasan_set_track+0x4e/0x80  kasan_save_free_info+0x28/0xb0  ____kasan_slab_free+0xfd/0x170  kmem_cache_free+0x183/0x3f0  hci_devcd_rx+0x91a/0x2060 [bluetooth]  worker_thread+0xe44/0x2cc0  kthread+0x2ff/0x3a0  ret_from_fork+0x51/0x80  ret_from_fork_asm+0x1b/0x30  The buggy address belongs to the object at ffff888033cfab40  which belongs to the cache skbuff_head_cache of size 232 The buggy address is located 112 bytes inside of  freed 232-byte region [ffff888033cfab40, ffff888033cfac28)  The buggy address belongs to the physical page: page:00000000a174ba93 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33cfa head:00000000a174ba93 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0 anon flags: 0x4000000000000840(slab|head|zone=1) page_type: 0xffffffff() raw: 4000000000000840 ffff888100848a00 0000000000000000 0000000000000001 raw: 0000000000000000 0000000080190019 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected  Memory state around the buggy address:  ffff888033cfaa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc  ffff888033cfab00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff888033cfab80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb                                      ^  ffff888033cfac00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc  ffff888033cfac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================  Check if we need to call hci_devcd_complete before calling hci_devcd_append. That requires that we check data->cd_info.cnt >= MTK_COREDUMP_NUM instead of data->cd_info.cnt > MTK_COREDUMP_NUM, as we increment data->cd_info.cnt only once the call to hci_devcd_append succeeds.