From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Jon Hunter <jonathanh@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	"Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
	Furong Xu <0x1207@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Rahul Sharma <black.hawk@163.com>
Subject: [PATCH 6.1 470/481] net: stmmac: fix TSO DMA API usage causing oops
Date: Mon, 23 Mar 2026 14:47:32 +0100
Message-ID: <20260323134536.672365608@linuxfoundation.org>
In-Reply-To: <20260323134525.256603107@linuxfoundation.org>
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6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>

[ Upstream commit 4c49f38e20a57f8abaebdf95b369295b153d1f8e ]

Commit 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap
for non-paged SKB data") moved the assignment of tx_skbuff_dma[]'s
members to be later in stmmac_tso_xmit().

The buf (dma cookie) and len stored in this structure are passed to
dma_unmap_single() by stmmac_tx_clean(). The DMA API requires that
the dma cookie passed to dma_unmap_single() is the same as the value
returned from dma_map_single(). However, by moving the assignment
later, this is not the case when priv->dma_cap.addr64 > 32 as "des"
is offset by proto_hdr_len.

This causes problems such as:

  dwc-eth-dwmac 2490000.ethernet eth0: Tx DMA map failed

and with DMA_API_DEBUG enabled:

  DMA-API: dwc-eth-dwmac 2490000.ethernet: device driver tries to +free DMA memory it has not allocated [device address=0x000000ffffcf65c0] [size=66 bytes]

Fix this by maintaining "des" as the original DMA cookie, and use
tso_des to pass the offset DMA cookie to stmmac_tso_allocator().

Full details of the crashes can be found at:
https://lore.kernel.org/all/d8112193-0386-4e14-b516-37c2d838171a@nvidia.com/
https://lore.kernel.org/all/klkzp5yn5kq5efgtrow6wbvnc46bcqfxs65nz3qy77ujr5turc@bwwhelz2l4dw/

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Reported-by: Thierry Reding <thierry.reding@gmail.com>
Fixes: 66600fac7a98 ("net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data")
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Furong Xu <0x1207@gmail.com>
Link: https://patch.msgid.link/E1tJXcx-006N4Z-PC@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ The context change is due to the commit 041cc86b3653
("net: stmmac: Enable TSO on VLANs") in v6.11 which is irrelevant to
the logic of this patch. ]
Signed-off-by: Rahul Sharma <black.hawk@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4091,10 +4091,10 @@ static netdev_tx_t stmmac_tso_xmit(struc
 	int tmp_pay_len = 0, first_tx;
 	struct stmmac_tx_queue *tx_q;
 	bool has_vlan, set_ic;
+	dma_addr_t tso_des, des;
 	u8 proto_hdr_len, hdr;
 	unsigned long flags;
 	u32 pay_len, mss;
-	dma_addr_t des;
 	int i;
 
 	tx_q = &priv->dma_conf.tx_queue[queue];
@@ -4179,14 +4179,15 @@ static netdev_tx_t stmmac_tso_xmit(struc
 
 		/* If needed take extra descriptors to fill the remaining payload */
 		tmp_pay_len = pay_len - TSO_MAX_BUFF_SIZE;
+		tso_des = des;
 	} else {
 		stmmac_set_desc_addr(priv, first, des);
 		tmp_pay_len = pay_len;
-		des += proto_hdr_len;
+		tso_des = des + proto_hdr_len;
 		pay_len = 0;
 	}
 
-	stmmac_tso_allocator(priv, des, tmp_pay_len, (nfrags == 0), queue);
+	stmmac_tso_allocator(priv, tso_des, tmp_pay_len, (nfrags == 0), queue);
 
 	/* In case two or more DMA transmit descriptors are allocated for this
 	 * non-paged SKB data, the DMA buffer address should be saved to