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IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs()

PATCH Superseded Tuo Li 2 participants 2 messages Aug 5, 2021

Subsystems (2)
InfiniBand HFI1 driver

v1 of 3 Superseded Latest is v3 →

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Tuo Li

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#0 lore raw

PATCH 1/1 IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs()

kmalloc_array() is called to allocate memory for tx->descp. If it fails, the function __sdma_txclean() is called:
__sdma_txclean(dd, tx);

However, in the function __sdma_txclean(), tx-descp is dereferenced if tx->num_desc is not zero:
sdma_unmap_desc(dd, &tx->descp[0]);

To fix this possible null-pointer dereference, assign 0 to tx->num_desc if kmalloc_array() returns NULL.

Reported-by TOTE Robot <[email protected]>
Signed-off-by Tuo Li <[email protected]>
---
 drivers/infiniband/hw/hfi1/sdma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
drivers/infiniband/hw/hfi1/sdma.c +3 -1
index eb15c310d63d..00e29c3dfe96 100644
@@ -3079,8 +3079,10 @@ static int _extend_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 			MAX_DESC,
 			sizeof(struct sdma_desc),
 			GFP_ATOMIC);
-	if (!tx->descp)
+	if (!tx->descp) {
+		tx->num_desc = 0;
 		goto enomem;
+	}
 
 	/* reserve last descriptor for coalescing */
 	tx->desc_limit = MAX_DESC - 1;
Signature · 1 line
2.25.1
#1 lore raw
Quoted 37 lines

Subject: [PATCH] IB/hfi1: Fix possible null-pointer dereference in _extend_sdma_tx_descs()

kmalloc_array() is called to allocate memory for tx->descp. If it fails, the function __sdma_txclean() is called:
__sdma_txclean(dd, tx);

However, in the function __sdma_txclean(), tx-descp is dereferenced if tx->num_desc is not zero:
sdma_unmap_desc(dd, &tx->descp[0]);

To fix this possible null-pointer dereference, assign 0 to tx->num_desc if kmalloc_array() returns NULL.

Reported-by TOTE Robot <[email protected]>
Signed-off-by Tuo Li <[email protected]>
---
 drivers/infiniband/hw/hfi1/sdma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
drivers/infiniband/hw/hfi1/sdma.c +3 -1
index eb15c310d63d..00e29c3dfe96 100644
@@ -3079,8 +3079,10 @@ static int _extend_sdma_tx_descs(struct
 hfi1_devdata *dd, struct sdma_txreq *tx)
 			MAX_DESC,
 			sizeof(struct sdma_desc),
 			GFP_ATOMIC);
-	if (!tx->descp)
+	if (!tx->descp) {
+		tx->num_desc = 0;
 		goto enomem;
+	}
 
 	/* reserve last descriptor for coalescing */
Quoted 1 line

tx->desc_limit = MAX_DESC - 1;

Thanks for seeing an issue here, but the correct solution is to store descp locally first.

Once the allocation is shown to be non-NULL, then store to tx-descp:

drivers/infiniband/hw/hfi1/sdma.c +6 -5
index eb15c310d..b6c554a 100644
@@ -3055,6 +3055,7 @@ static void __sdma_process_event(struct sdma_engine *sde,
 static int _extend_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
 {
        int i;
+       struct sdma_desc *descp;
 
        /* Handle last descriptor */
        if (unlikely((tx->num_desc == (MAX_DESC - 1)))) {

@@ -3075,12 +3076,12 @@ static int _extend_sdma_tx_descs(struct hfi1_devdata *dd, struct sdma_txreq *tx)
        if (unlikely(tx->num_desc == MAX_DESC))
                goto enomem;
 
-       tx->descp = kmalloc_array(
-                       MAX_DESC,
-                       sizeof(struct sdma_desc),
-                       GFP_ATOMIC);
-       if (!tx->descp)
+       descp = kmalloc_array(MAX_DESC,
+                             sizeof(struct sdma_desc),
+                             GFP_ATOMIC);
+       if (!descp)
                goto enomem;
+       tx->descp = descp;
 
        /* reserve last descriptor for coalescing */
        tx->desc_limit = MAX_DESC - 1;