sfc: allocate a big enough SKB for loopback selftest packet

Cited commits passed a size to alloc_skb that was only big enough for
 the actual packet contents, but the following skb_put + memcpy writes
 the whole struct efx_loopback_payload including leading and trailing
 padding bytes (which are then stripped off with skb_pull/skb_trim).
This could cause an skb_over_panic, although in practice we get saved
 by kmalloc_size_roundup.
Pass the entire size we use, instead of the size of the final packet.

Reported-by: Andy Moreton <andy.moreton@amd.com>
Fixes: cf60ed469629 ("sfc: use padding to fix alignment in loopback test")
Fixes: 30c24dd87f3f ("sfc: siena: use padding to fix alignment in loopback test")
Fixes: 1186c6b31ee1 ("sfc: falcon: use padding to fix alignment in loopback test")
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230821180153.18652-1-edward.cree@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/sfc/falcon/selftest.c b/drivers/net/ethernet/sfc/falcon/selftest.c
index cf1d67b..c3dc88e 100644 (file)
--- a/drivers/net/ethernet/sfc/falcon/selftest.c
+++ b/drivers/net/ethernet/sfc/falcon/selftest.c
@@ -428,7 +428,7 @@ static int ef4_begin_loopback(struct ef4_tx_queue *tx_queue)
        for (i = 0; i < state->packet_count; i++) {
                /* Allocate an skb, holding an extra reference for
                 * transmit completion counting */
-               skb = alloc_skb(EF4_LOOPBACK_PAYLOAD_LEN, GFP_KERNEL);
+               skb = alloc_skb(sizeof(state->payload), GFP_KERNEL);
                if (!skb)
                        return -ENOMEM;
                state->skbs[i] = skb;

diff --git a/drivers/net/ethernet/sfc/selftest.c b/drivers/net/ethernet/sfc/selftest.c
index 19a0b85..563c1e3 100644 (file)
--- a/drivers/net/ethernet/sfc/selftest.c
+++ b/drivers/net/ethernet/sfc/selftest.c
@@ -426,7 +426,7 @@ static int efx_begin_loopback(struct efx_tx_queue *tx_queue)
        for (i = 0; i < state->packet_count; i++) {
                /* Allocate an skb, holding an extra reference for
                 * transmit completion counting */
-               skb = alloc_skb(EFX_LOOPBACK_PAYLOAD_LEN, GFP_KERNEL);
+               skb = alloc_skb(sizeof(state->payload), GFP_KERNEL);
                if (!skb)
                        return -ENOMEM;
                state->skbs[i] = skb;

diff --git a/drivers/net/ethernet/sfc/siena/selftest.c b/drivers/net/ethernet/sfc/siena/selftest.c
index b55fd33..526da43 100644 (file)
--- a/drivers/net/ethernet/sfc/siena/selftest.c
+++ b/drivers/net/ethernet/sfc/siena/selftest.c
@@ -426,7 +426,7 @@ static int efx_begin_loopback(struct efx_tx_queue *tx_queue)
        for (i = 0; i < state->packet_count; i++) {
                /* Allocate an skb, holding an extra reference for
                 * transmit completion counting */
-               skb = alloc_skb(EFX_LOOPBACK_PAYLOAD_LEN, GFP_KERNEL);
+               skb = alloc_skb(sizeof(state->payload), GFP_KERNEL);
                if (!skb)
                        return -ENOMEM;
                state->skbs[i] = skb;