جزئیات آسیب‌پذیری

In the Linux kernel, the following vulnerability has been resolved: greybus: raw: fix use-after-free if write is called after disconnect If a user writes to the chardev after disconnect has been called, the kernel panics with the following trace (with CONFIG_INIT_ON_FREE_DEFAULT_ON=y): BUG: kernel NULL pointer dereference, address: 0000000000000218 ... Call Trace: <TASK> gb_operation_create_common+0x61/0x180 gb_operation_create_flags+0x28/0xa0 gb_operation_sync_timeout+0x6f/0x100 raw_write+0x7b/0xc7 [gb_raw] vfs_write+0xcf/0x420 ? task_mm_cid_work+0x136/0x220 ksys_write+0x63/0xe0 do_syscall_64+0xa4/0x290 entry_SYSCALL_64_after_hwframe+0x77/0x7f Disconnect calls gb_connection_destroy, which ends up freeing the connection object. When gb_operation_sync is called in the write file operations, its gets a freed connection as parameter and the kernel panics. The gb_connection_destroy cannot be moved out of the disconnect function, as the Greybus subsystem expect all connections belonging to a bundle to be destroyed when disconnect returns. To prevent this bug, use a rw lock to synchronize access between write and disconnect. This guarantees that the write function doesn't try to use a disconnected connection.

• https://git.kernel.org/stable/c/5a6ce05ccd9eca653b09d67eb59026821ffaf61b
• https://git.kernel.org/stable/c/966b941ca469fb794637a0803670454f68515e40
• https://git.kernel.org/stable/c/2b46f07913a80521ecfe60b229c84bdd7dfb15ab
• https://git.kernel.org/stable/c/48d6c32bc049abd114e8f0836c0e7d7cbfba7827
• https://git.kernel.org/stable/c/84265cbd96b97058ef67e3f8be3933667a000835