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From:   Xiaomeng Tong <xiam0nd.tong@gmail.com>
To:     dinguyen@kernel.org
Cc:     gregkh@linuxfoundation.org, atull@kernel.org,
        richard.gong@intel.com, linux-kernel@vger.kernel.org,
        Xiaomeng Tong <xiam0nd.tong@gmail.com>, stable@vger.kernel.org
Subject: [PATCH] firmware: stratix10-svc: fix a missing check on list iterator
Date:   Sun, 27 Mar 2022 14:13:43 +0800
Message-Id: <20220327061343.4995-1-xiam0nd.tong@gmail.com>
Precedence: bulk

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;

Cc: stable@vger.kernel.org
Fixes: 7ca5ce896524f ("firmware: add Intel Stratix10 service layer driver")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
---
 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 29c0a616b317..30093aa82b7f 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);
 
-- 
2.17.1