firewire: core: fix race condition in split transaction handling

For a split transaction, either fw_core_handle_response() or
split_transaction_timeout_callback() may manipulate the same transaction
entry in the pending transaction list. The return value of timer_delete()
is used to determine which function handles the entry. If the transaction
is a split transaction and timer_delete() returns zero, the timeout
callback may already be running. In this case, the response handler must
leave the entry in the list for the timeout callback to remove.

A previous code refactoring broke this behavior, introducing a race
condition in which both functions could process the same transaction.
This could lead to a use-after-free on the transaction initiator side.

Fix the regression by ensuring that the response handler does not process
the transaction when timer_delete() returns zero. The timeout callback is
responsible for removing the entry from the pending transaction list.

Fixes: fa2dc2710076 ("firewire: core: code refactoring to find and pop transaction entry")
Link: https://lore.kernel.org/r/20261018025504.290598-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

0 files changed, 0 insertions, 0 deletions