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dpll: fix NULL pointer dereference in dpll_msg_add_pin_ref_sync()

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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.

Fixes: 58256a26bf ("dpll: add reference sync get/set")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://patch.msgid.link/20260710193625.1378822-1-ivecera@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Ivan Vecera 2026-07-10 21:36:25 +02:00 committed by Paolo Abeni
parent 2c1931a811
commit d2e914a4a0
1 changed files with 3 additions and 0 deletions
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3
drivers/dpll/dpll_netlink.c
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@ -567,6 +567,9 @@ dpll_msg_add_pin_ref_sync(struct sk_buff *msg, struct dpll_pin *pin,
if (!dpll_pin_available(ref_sync_pin))
continue;
ref_sync_pin_priv = dpll_pin_on_dpll_priv(dpll, ref_sync_pin);
/* Pin may have been unregistered from this dpll already */
if (!ref_sync_pin_priv)
continue;
if (WARN_ON(!ops->ref_sync_get))
return -EOPNOTSUPP;
ret = ops->ref_sync_get(pin, pin_priv, ref_sync_pin,