[PATCH 5.15 023/247] firmware: stratix10-svc: fix a missing check on list iterator

[Greg Kroah-Hartman]

From: Xiaomeng Tong <xiam0nd.tong@xxxxxxxxx>

[ Upstream commit 5a0793ac66ac0e254d292f129a4d6c526f9f2aff ]

The bug is here:
	pmem->vaddr = NULL;

The list iterator 'pmem' will point to a bogus position containing
HEAD if the list is empty or no element is found. This case must
be checked before any use of the iterator, otherwise it will
lead to a invalid memory access.

To fix this bug, just gen_pool_free/set NULL/list_del() and return
when found, otherwise list_del HEAD and return;

Fixes: 7ca5ce896524f ("firmware: add Intel Stratix10 service layer driver")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@xxxxxxxxx>
Link: https://lore.kernel.org/r/20220414035609.2239-1-xiam0nd.tong@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/firmware/stratix10-svc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/stratix10-svc.c b/drivers/firmware/stratix10-svc.c
index 53c7e3f8cfde..7dd0ac1a0cfc 100644
--- a/drivers/firmware/stratix10-svc.c
+++ b/drivers/firmware/stratix10-svc.c
@@ -941,17 +941,17 @@ EXPORT_SYMBOL_GPL(stratix10_svc_allocate_memory);
 void stratix10_svc_free_memory(struct stratix10_svc_chan *chan, void *kaddr)
 {
 	struct stratix10_svc_data_mem *pmem;
-	size_t size = 0;
 
 	list_for_each_entry(pmem, &svc_data_mem, node)
 		if (pmem->vaddr == kaddr) {
-			size = pmem->size;
-			break;
+			gen_pool_free(chan->ctrl->genpool,
+				       (unsigned long)kaddr, pmem->size);
+			pmem->vaddr = NULL;
+			list_del(&pmem->node);
+			return;
 		}
 
-	gen_pool_free(chan->ctrl->genpool, (unsigned long)kaddr, size);
-	pmem->vaddr = NULL;
-	list_del(&pmem->node);
+	list_del(&svc_data_mem);
 }
 EXPORT_SYMBOL_GPL(stratix10_svc_free_memory);
 
-- 
2.35.1