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Message-Id: <20200825172736.27318-4-bjorn.topel@gmail.com>
Date: Tue, 25 Aug 2020 19:27:36 +0200
From: Björn Töpel <bjorn.topel@...il.com>
To: jeffrey.t.kirsher@...el.com, intel-wired-lan@...ts.osuosl.org
Cc: Björn Töpel <bjorn.topel@...el.com>,
magnus.karlsson@...el.com, magnus.karlsson@...il.com,
netdev@...r.kernel.org, maciej.fijalkowski@...el.com,
piotr.raczynski@...el.com, maciej.machnikowski@...el.com,
lirongqing@...du.com
Subject: [PATCH net v3 3/3] ice: avoid premature Rx buffer reuse
From: Björn Töpel <bjorn.topel@...el.com>
The page recycle code, incorrectly, relied on that a page fragment
could not be freed inside xdp_do_redirect(). This assumption leads to
that page fragments that are used by the stack/XDP redirect can be
reused and overwritten.
To avoid this, store the page count prior invoking xdp_do_redirect().
Fixes: efc2214b6047 ("ice: Add support for XDP")
Reported-and-analyzed-by: Li RongQing <lirongqing@...du.com>
Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
---
drivers/net/ethernet/intel/ice/ice_txrx.c | 30 ++++++++++++++++-------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
index 9d0d6b0025cf..61279adf3561 100644
--- a/drivers/net/ethernet/intel/ice/ice_txrx.c
+++ b/drivers/net/ethernet/intel/ice/ice_txrx.c
@@ -762,13 +762,15 @@ ice_rx_buf_adjust_pg_offset(struct ice_rx_buf *rx_buf, unsigned int size)
/**
* ice_can_reuse_rx_page - Determine if page can be reused for another Rx
* @rx_buf: buffer containing the page
+ * @rx_buf_pgcnt: rx_buf page refcount pre xdp_do_redirect() call
*
* If page is reusable, we have a green light for calling ice_reuse_rx_page,
* which will assign the current buffer to the buffer that next_to_alloc is
* pointing to; otherwise, the DMA mapping needs to be destroyed and
* page freed
*/
-static bool ice_can_reuse_rx_page(struct ice_rx_buf *rx_buf)
+static bool ice_can_reuse_rx_page(struct ice_rx_buf *rx_buf,
+ int rx_buf_pgcnt)
{
unsigned int pagecnt_bias = rx_buf->pagecnt_bias;
struct page *page = rx_buf->page;
@@ -779,7 +781,7 @@ static bool ice_can_reuse_rx_page(struct ice_rx_buf *rx_buf)
#if (PAGE_SIZE < 8192)
/* if we are only owner of page we can reuse it */
- if (unlikely((page_count(page) - pagecnt_bias) > 1))
+ if (unlikely((rx_buf_pgcnt - pagecnt_bias) > 1))
return false;
#else
#define ICE_LAST_OFFSET \
@@ -864,17 +866,25 @@ ice_reuse_rx_page(struct ice_ring *rx_ring, struct ice_rx_buf *old_buf)
* @rx_ring: Rx descriptor ring to transact packets on
* @skb: skb to be used
* @size: size of buffer to add to skb
+ * @rx_buf_pgcnt: rx_buf page refcount
*
* This function will pull an Rx buffer from the ring and synchronize it
* for use by the CPU.
*/
static struct ice_rx_buf *
ice_get_rx_buf(struct ice_ring *rx_ring, struct sk_buff **skb,
- const unsigned int size)
+ const unsigned int size,
+ int *rx_buf_pgcnt)
{
struct ice_rx_buf *rx_buf;
rx_buf = &rx_ring->rx_buf[rx_ring->next_to_clean];
+ *rx_buf_pgcnt =
+#if (PAGE_SIZE < 8192)
+ page_count(rx_buf->page);
+#else
+ 0;
+#endif
prefetchw(rx_buf->page);
*skb = rx_buf->skb;
@@ -1012,12 +1022,13 @@ ice_construct_skb(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf,
* ice_put_rx_buf - Clean up used buffer and either recycle or free
* @rx_ring: Rx descriptor ring to transact packets on
* @rx_buf: Rx buffer to pull data from
+ * @rx_buf_pgcnt: Rx buffer page count pre xdp_do_redirect()
*
* This function will update next_to_clean and then clean up the contents
* of the rx_buf. It will either recycle the buffer or unmap it and free
* the associated resources.
*/
-static void ice_put_rx_buf(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf)
+static void ice_put_rx_buf(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf, int rx_buf_pgcnt)
{
u16 ntc = rx_ring->next_to_clean + 1;
@@ -1028,7 +1039,7 @@ static void ice_put_rx_buf(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf)
if (!rx_buf)
return;
- if (ice_can_reuse_rx_page(rx_buf)) {
+ if (ice_can_reuse_rx_page(rx_buf, rx_buf_pgcnt)) {
/* hand second half of page back to the ring */
ice_reuse_rx_page(rx_ring, rx_buf);
} else {
@@ -1103,6 +1114,7 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
struct sk_buff *skb;
unsigned int size;
u16 stat_err_bits;
+ int rx_buf_pgcnt;
u16 vlan_tag = 0;
u8 rx_ptype;
@@ -1125,7 +1137,7 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
dma_rmb();
if (rx_desc->wb.rxdid == FDIR_DESC_RXDID || !rx_ring->netdev) {
- ice_put_rx_buf(rx_ring, NULL);
+ ice_put_rx_buf(rx_ring, NULL, 0);
cleaned_count++;
continue;
}
@@ -1134,7 +1146,7 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
ICE_RX_FLX_DESC_PKT_LEN_M;
/* retrieve a buffer from the ring */
- rx_buf = ice_get_rx_buf(rx_ring, &skb, size);
+ rx_buf = ice_get_rx_buf(rx_ring, &skb, size, &rx_buf_pgcnt);
if (!size) {
xdp.data = NULL;
@@ -1174,7 +1186,7 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
total_rx_pkts++;
cleaned_count++;
- ice_put_rx_buf(rx_ring, rx_buf);
+ ice_put_rx_buf(rx_ring, rx_buf, rx_buf_pgcnt);
continue;
construct_skb:
if (skb) {
@@ -1193,7 +1205,7 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
break;
}
- ice_put_rx_buf(rx_ring, rx_buf);
+ ice_put_rx_buf(rx_ring, rx_buf, rx_buf_pgcnt);
cleaned_count++;
/* skip if it is NOP desc */
--
2.25.1
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