From: Jakob Koschel jakobkoschel@gmail.com
commit 9423973869bd4632ffe669f950510c49296656e0 upstream.
When list_for_each_entry() completes the iteration over the whole list without breaking the loop, the iterator value will be a bogus pointer computed based on the head element.
While it is safe to use the pointer to determine if it was computed based on the head element, either with list_entry_is_head() or &pos->member == head, using the iterator variable after the loop should be avoided.
In preparation to limit the scope of a list iterator to the list traversal loop, use a dedicated pointer to point to the found element [1].
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWX... [1] Cc: stable@vger.kernel.org Signed-off-by: Jakob Koschel jakobkoschel@gmail.com Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp Link: https://lore.kernel.org/r/20220409041243.603210-3-o-takashi@sakamocchi.jp Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/firewire/core-transaction.c | 30 ++++++++++++++++-------------- drivers/firewire/sbp2.c | 13 +++++++------ 2 files changed, 23 insertions(+), 20 deletions(-)
--- a/drivers/firewire/core-transaction.c +++ b/drivers/firewire/core-transaction.c @@ -86,24 +86,25 @@ static int try_cancel_split_timeout(stru static int close_transaction(struct fw_transaction *transaction, struct fw_card *card, int rcode) { - struct fw_transaction *t; + struct fw_transaction *t = NULL, *iter; unsigned long flags;
spin_lock_irqsave(&card->lock, flags); - list_for_each_entry(t, &card->transaction_list, link) { - if (t == transaction) { - if (!try_cancel_split_timeout(t)) { + list_for_each_entry(iter, &card->transaction_list, link) { + if (iter == transaction) { + if (!try_cancel_split_timeout(iter)) { spin_unlock_irqrestore(&card->lock, flags); goto timed_out; } - list_del_init(&t->link); - card->tlabel_mask &= ~(1ULL << t->tlabel); + list_del_init(&iter->link); + card->tlabel_mask &= ~(1ULL << iter->tlabel); + t = iter; break; } } spin_unlock_irqrestore(&card->lock, flags);
- if (&t->link != &card->transaction_list) { + if (t) { t->callback(card, rcode, NULL, 0, t->callback_data); return 0; } @@ -938,7 +939,7 @@ EXPORT_SYMBOL(fw_core_handle_request);
void fw_core_handle_response(struct fw_card *card, struct fw_packet *p) { - struct fw_transaction *t; + struct fw_transaction *t = NULL, *iter; unsigned long flags; u32 *data; size_t data_length; @@ -950,20 +951,21 @@ void fw_core_handle_response(struct fw_c rcode = HEADER_GET_RCODE(p->header[1]);
spin_lock_irqsave(&card->lock, flags); - list_for_each_entry(t, &card->transaction_list, link) { - if (t->node_id == source && t->tlabel == tlabel) { - if (!try_cancel_split_timeout(t)) { + list_for_each_entry(iter, &card->transaction_list, link) { + if (iter->node_id == source && iter->tlabel == tlabel) { + if (!try_cancel_split_timeout(iter)) { spin_unlock_irqrestore(&card->lock, flags); goto timed_out; } - list_del_init(&t->link); - card->tlabel_mask &= ~(1ULL << t->tlabel); + list_del_init(&iter->link); + card->tlabel_mask &= ~(1ULL << iter->tlabel); + t = iter; break; } } spin_unlock_irqrestore(&card->lock, flags);
- if (&t->link == &card->transaction_list) { + if (!t) { timed_out: fw_notice(card, "unsolicited response (source %x, tlabel %x)\n", source, tlabel); --- a/drivers/firewire/sbp2.c +++ b/drivers/firewire/sbp2.c @@ -421,7 +421,7 @@ static void sbp2_status_write(struct fw_ void *payload, size_t length, void *callback_data) { struct sbp2_logical_unit *lu = callback_data; - struct sbp2_orb *orb; + struct sbp2_orb *orb = NULL, *iter; struct sbp2_status status; unsigned long flags;
@@ -446,17 +446,18 @@ static void sbp2_status_write(struct fw_
/* Lookup the orb corresponding to this status write. */ spin_lock_irqsave(&lu->tgt->lock, flags); - list_for_each_entry(orb, &lu->orb_list, link) { + list_for_each_entry(iter, &lu->orb_list, link) { if (STATUS_GET_ORB_HIGH(status) == 0 && - STATUS_GET_ORB_LOW(status) == orb->request_bus) { - orb->rcode = RCODE_COMPLETE; - list_del(&orb->link); + STATUS_GET_ORB_LOW(status) == iter->request_bus) { + iter->rcode = RCODE_COMPLETE; + list_del(&iter->link); + orb = iter; break; } } spin_unlock_irqrestore(&lu->tgt->lock, flags);
- if (&orb->link != &lu->orb_list) { + if (orb) { orb->callback(orb, &status); kref_put(&orb->kref, free_orb); /* orb callback reference */ } else {