In the Linux kernel, the following vulnerability has been resolved: dpll: fix NULL pointer dereference in dpll_msg_add_pin_ref_sync() When a dpll_pin is shared across multiple dpll_device instances and those devices are being unregistered (e.g. during driver module removal), a NULL pointer dereference can occur in dpll_msg_add_pin_ref_sync(). This happens under the following conditions: - A pin is registered with two or more dpll devices (dpll_A, dpll_B) - The pin has ref_sync pairs with other pins - During unregistration of dpll_A's pins, a ref_sync partner pin is unregistered first, removing it from dpll_A->pin_refs - But since the partner pin is still registered with dpll_B, its dpll_refs is not empty, so dpll_pin_ref_sync_pair_del() does NOT run and the partner stays in the pin's ref_sync_pins xarray - When the pin itself is then unregistered from dpll_A, the delete notification calls dpll_msg_add_pin_ref_sync() which finds the partner in ref_sync_pins, passes dpll_pin_available() (partner is still registered with dpll_B), but dpll_pin_on_dpll_priv(dpll_A, partner) returns NULL because partner was already removed from dpll_A->pin_refs - The NULL priv pointer is passed to the driver's ref_sync_get callback, which dereferences it BUG: kernel NULL pointer dereference, address: 0000000000000034 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:zl3073x_dpll_input_pin_ref_sync_get+0x73/0x80 [zl3073x] Call Trace: dpll_msg_add_pin_ref_sync+0xb8/0x200 dpll_cmd_pin_get_one+0x3b6/0x4b0 dpll_pin_event_send+0x72/0x140 __dpll_pin_unregister+0x5a/0x2b0 dpll_pin_unregister+0x49/0x70 Fix this by skipping ref_sync pins whose priv pointer cannot be resolved for the current dpll device.

Quoted source text, attributed separately from HOL analysis.

In the Linux kernel, the following vulnerability has been resolved: dpll: fix NULL pointer dereference in dpll_msg_add_pin_ref_sync() When a dpll_pin is shared across multiple dpll_device instances and those devices are being unregistered (e.g. during driver module removal), a NULL pointer dereference can occur in dpll_msg_add_pin_ref_sync(). This happens under the following conditions: - A pin is registered with two or more dpll devices (dpll_A, dpll_B) - The pin has ref_sync pairs with other pins - During unregistration of dpll_A's pins, a ref_sync partner pin is unregistered first, removing it from dpll_A->pin_refs - But since the partner pin is still registered with dpll_B, its dpll_refs is not empty, so dpll_pin_ref_sync_pair_del() does NOT run and the partner stays in the pin's ref_sync_pins xarray - When the pin itself is then unregistered from dpll_A, the delete notification calls dpll_msg_add_pin_ref_sync() which finds the partner in ref_sync_pins, passes dpll_pin_available() (partner is still registered with dpll_B), but dpll_pin_on_dpll_priv(dpll_A, partner) returns NULL because partner was already removed from dpll_A->pin_refs - The NULL priv pointer is passed to the driver's ref_sync_get callback, which dereferences it BUG: kernel NULL pointer dereference, address: 0000000000000034 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:zl3073x_dpll_input_pin_ref_sync_get+0x73/0x80 [zl3073x] Call Trace: dpll_msg_add_pin_ref_sync+0xb8/0x200 dpll_cmd_pin_get_one+0x3b6/0x4b0 dpll_pin_event_send+0x72/0x140 __dpll_pin_unregister+0x5a/0x2b0 dpll_pin_unregister+0x49/0x70 Fix this by skipping ref_sync pins whose priv pointer cannot be resolved for the current dpll device.

Quoted source text, attributed separately from HOL analysis.