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Subject[PATCH 4.14 35/82] igb: Fix use-after-free error during reset
From: Vinicius Costa Gomes <>

[ Upstream commit 7b292608db23ccbbfbfa50cdb155d01725d7a52e ]

Cleans the next descriptor to watch (next_to_watch) when cleaning the
TX ring.

Failure to do so can cause invalid memory accesses. If igb_poll() runs
while the controller is reset this can lead to the driver try to free
a skb that was already freed.

(The crash is harder to reproduce with the igb driver, but the same
potential problem exists as the code is identical to igc)

Fixes: 7cc6fd4c60f2 ("igb: Don't bother clearing Tx buffer_info in igb_clean_tx_ring")
Signed-off-by: Vinicius Costa Gomes <>
Reported-by: Erez Geva <>
Tested-by: Tony Brelinski <>
Signed-off-by: Tony Nguyen <>
Signed-off-by: Sasha Levin <>
drivers/net/ethernet/intel/igb/igb_main.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 50fa0401c701..36c656736811 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3962,6 +3962,8 @@ static void igb_clean_tx_ring(struct igb_ring *tx_ring)

+ tx_buffer->next_to_watch = NULL;
/* move us one more past the eop_desc for start of next pkt */

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