lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Fri, 10 Oct 2014 04:48:15 -0700
From:	Eric Dumazet <>
To:	"David S. Miller" <>
	Alexander Duyck <>,
	Jeff Kirsher <>,
	Andres Lagar-Cavilla <>,
	Greg Thelen <>,
	Hugh Dickins <>,
	David Rientjes <>,
	Eric Dumazet <>
Subject: [PATCH v2 net 2/5] igb: fix race accessing page->_count

This is illegal to use atomic_set(&page->_count, 2) even if we 'own'
the page. Other entities in the kernel need to use get_page_unless_zero()
to get a reference to the page before testing page properties, so we could
loose a refcount increment.

Signed-off-by: Eric Dumazet <>
Acked-by: Jeff Kirsher <>
 drivers/net/ethernet/intel/igb/igb_main.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index ae59c0b108c5..a21b14495ebd 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -6545,11 +6545,10 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer,
 	/* flip page offset to other buffer */
 	rx_buffer->page_offset ^= IGB_RX_BUFSZ;
-	/* since we are the only owner of the page and we need to
-	 * increment it, just set the value to 2 in order to avoid
-	 * an unnecessary locked operation
+	/* Even if we own the page, we are not allowed to use atomic_set()
+	 * This would break get_page_unless_zero() users.
-	atomic_set(&page->_count, 2);
+	atomic_inc(&page->_count);
 	/* move offset up to the next cache line */
 	rx_buffer->page_offset += truesize;

To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists