netdev - [PATCH] net: atlantic: fix double free in ring reinit logic

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Date: Wed, 13 Dec 2023 10:40:44 +0100
From: Igor Russkikh <irusskikh@...vell.com>
To: <netdev@...r.kernel.org>
CC: "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski
	<kuba@...nel.org>,
        Igor Russkikh <irusskikh@...vell.com>,
        Linus Torvalds
	<torvalds@...ux-foundation.org>
Subject: [PATCH] net: atlantic: fix double free in ring reinit logic

Driver has a logic leak in ring data allocation/free,
where double free may happen in aq_ring_free if system is under
stress and driver init/deinit is happening.

The probability is higher to get this during suspend/resume cycle.

Verification was done simulating same conditions with

    stress -m 2000 --vm-bytes 20M --vm-hang 10 --backoff 1000
    while true; do sudo ifconfig enp1s0 down; sudo ifconfig enp1s0 up; done

Fixed by explicitly clearing pointers to NULL on deallocation

Fixes: 018423e90bee ("net: ethernet: aquantia: Add ring support code")
Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Closes: https://lore.kernel.org/netdev/CAHk-=wiZZi7FcvqVSUirHBjx0bBUZ4dFrMDVLc3+3HCrtq0rBA@mail.gmail.com/
Signed-off-by: Igor Russkikh <irusskikh@...vell.com>
---
 drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 4de22eed099a..472c7c08bfed 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -932,11 +932,14 @@ void aq_ring_free(struct aq_ring_s *self)
 		return;
 
 	kfree(self->buff_ring);
+	self->buff_ring = NULL;
 
-	if (self->dx_ring)
+	if (self->dx_ring) {
 		dma_free_coherent(aq_nic_get_dev(self->aq_nic),
 				  self->size * self->dx_size, self->dx_ring,
 				  self->dx_ring_pa);
+		self->dx_ring = NULL;
+	}
 }
 
 unsigned int aq_ring_fill_stats_data(struct aq_ring_s *self, u64 *data)
-- 
2.25.1