[PATCH v2 net] net: lan743x: Fix memleak issue when GSO enabled

[PATCH v2 net] net: lan743x: Fix memleak issue when GSO enabled

[Thangaraj Samynathan]

Always map the `skb` to the LS descriptor. Previously skb was
mapped to EXT descriptor when the number of fragments is zero with
GSO enabled. Mapping the skb to EXT descriptor prevents it from
being freed, leading to a memory leak

Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")
Signed-off-by: Thangaraj Samynathan <thangaraj.s@microchip.com>
---
v1
-Intial Submission

v2
-Modify the description to imperative mood

---
 drivers/net/ethernet/microchip/lan743x_main.c | 8 ++++++--
 drivers/net/ethernet/microchip/lan743x_main.h | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 8b6b9b6efe18..73dfc85fa67e 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1815,6 +1815,7 @@ static void lan743x_tx_frame_add_lso(struct lan743x_tx *tx,
 	if (nr_frags <= 0) {
 		tx->frame_data0 |= TX_DESC_DATA0_LS_;
 		tx->frame_data0 |= TX_DESC_DATA0_IOC_;
+		tx->frame_last = tx->frame_first;
 	}
 	tx_descriptor = &tx->ring_cpu_ptr[tx->frame_tail];
 	tx_descriptor->data0 = cpu_to_le32(tx->frame_data0);
@@ -1884,6 +1885,7 @@ static int lan743x_tx_frame_add_fragment(struct lan743x_tx *tx,
 		tx->frame_first = 0;
 		tx->frame_data0 = 0;
 		tx->frame_tail = 0;
+		tx->frame_last = 0;
 		return -ENOMEM;
 	}
 
@@ -1924,16 +1926,18 @@ static void lan743x_tx_frame_end(struct lan743x_tx *tx,
 	    TX_DESC_DATA0_DTYPE_DATA_) {
 		tx->frame_data0 |= TX_DESC_DATA0_LS_;
 		tx->frame_data0 |= TX_DESC_DATA0_IOC_;
+		tx->frame_last = tx->frame_tail;
 	}
 
-	tx_descriptor = &tx->ring_cpu_ptr[tx->frame_tail];
-	buffer_info = &tx->buffer_info[tx->frame_tail];
+	tx_descriptor = &tx->ring_cpu_ptr[tx->frame_last];
+	buffer_info = &tx->buffer_info[tx->frame_last];
 	buffer_info->skb = skb;
 	if (time_stamp)
 		buffer_info->flags |= TX_BUFFER_INFO_FLAG_TIMESTAMP_REQUESTED;
 	if (ignore_sync)
 		buffer_info->flags |= TX_BUFFER_INFO_FLAG_IGNORE_SYNC;
 
+	tx_descriptor = &tx->ring_cpu_ptr[tx->frame_tail];
 	tx_descriptor->data0 = cpu_to_le32(tx->frame_data0);
 	tx->frame_tail = lan743x_tx_next_index(tx, tx->frame_tail);
 	tx->last_tail = tx->frame_tail;
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h
index 7f73d66854be..db5fc73e41cc 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -980,6 +980,7 @@ struct lan743x_tx {
 	u32		frame_first;
 	u32		frame_data0;
 	u32		frame_tail;
+	u32		frame_last;
 
 	struct lan743x_tx_buffer_info *buffer_info;
 
-- 
2.25.1

Re: [PATCH v2 net] net: lan743x: Fix memleak issue when GSO enabled

[Jacob Keller]

On 4/28/2025 10:25 PM, Thangaraj Samynathan wrote:
> Always map the `skb` to the LS descriptor. Previously skb was
> mapped to EXT descriptor when the number of fragments is zero with
> GSO enabled. Mapping the skb to EXT descriptor prevents it from
> being freed, leading to a memory leak
> 
> Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")
> Signed-off-by: Thangaraj Samynathan <thangaraj.s@microchip.com>
> ---
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

Re: [PATCH v2 net] net: lan743x: Fix memleak issue when GSO enabled

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 29 Apr 2025 10:55:27 +0530 you wrote:
> Always map the `skb` to the LS descriptor. Previously skb was
> mapped to EXT descriptor when the number of fragments is zero with
> GSO enabled. Mapping the skb to EXT descriptor prevents it from
> being freed, leading to a memory leak
> 
> Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")
> Signed-off-by: Thangaraj Samynathan <thangaraj.s@microchip.com>
> 
> [...]

Here is the summary with links:
  - [v2,net] net: lan743x: Fix memleak issue when GSO enabled
    https://git.kernel.org/netdev/net/c/2d52e2e38b85

You are awesome, thank you!
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