[PATCH 6.1 218/219] [PATCH 5.15 6.1] gve: Fix use-after-free vulnerability

Greg Kroah-Hartman
2024-02-03T04:11:15Z

From: Praveen Kaligineedi <pkaligineedi@google.com>

From: Bailey Forrest <bcf@google.com>

Call skb_shinfo() after gve_prep_tso() on DQO TX path.
gve_prep_tso() calls skb_cow_head(), which may reallocate
shinfo causing a use after free.

This bug was unintentionally fixed by 'a6fb8d5a8b69
("gve: Tx path for DQO-QPL")' while adding DQO-QPL format
support in 6.6. That patch is not appropriate for stable releases.

Fixes: a57e5de476be ("gve: DQO: Add TX path")
Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Bailey Forrest <bcf@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jeroen de Borst <jeroendb@google.com>
Reviewed-by: Kevin DeCabooter <decabooter@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/google/gve/gve_tx_dqo.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
@@ -350,6 +350,7 @@ static void gve_tx_fill_pkt_desc_dqo(str
/* Validates and prepares `skb` for TSO.
*
* Returns header length, or < 0 if invalid.
+ * Warning : Might change skb->head (and thus skb_shinfo).
*/
static int gve_prep_tso(struct sk_buff *skb)
{
@@ -451,8 +452,8 @@ gve_tx_fill_general_ctx_desc(struct gve_
static int gve_tx_add_skb_no_copy_dqo(struct gve_tx_ring *tx,
struct sk_buff *skb)
{
- const struct skb_shared_info *shinfo = skb_shinfo(skb);
const bool is_gso = skb_is_gso(skb);
+ struct skb_shared_info *shinfo;
u32 desc_idx = tx->dqo_tx.tail;

struct gve_tx_pending_packet_dqo *pkt;
@@ -477,6 +478,8 @@ static int gve_tx_add_skb_no_copy_dqo(st
desc_idx = (desc_idx + 1) & tx->mask;
}

+ /* Must get after gve_prep_tso(), which can change shinfo. */
+ shinfo = skb_shinfo(skb);
gve_tx_fill_general_ctx_desc(&tx->dqo.tx_ring[desc_idx].general_ctx,
&metadata);
desc_idx = (desc_idx + 1) & tx->mask;