diff options
| author | Michael Bommarito <michael.bommarito@gmail.com> | 2026-06-22 08:47:22 -0400 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2026-07-23 21:31:14 +0200 |
| commit | af421e9aed3920c7ac88c24daa48606c7112feca (patch) | |
| tree | 972fc6d4ce68ffd2e2afc878bd00a49a8b5e4355 | |
| parent | 1590cf0329716306e948a8fc29f1d3ee87d3989f (diff) | |
um: vector: fix use-after-free in vector_mmsg_rx()
When vector_mmsg_rx() discards a packet whose overlay header fails
verify_header(), it frees the skb and continues the loop:
if (header_check < 0) {
dev_kfree_skb_irq(skb);
vp->estats.rx_encaps_errors++;
continue;
}
The normal and short-packet paths fall through to the bottom of the
loop body, which clears the consumed slot and advances the cursors:
(*skbuff_vector) = NULL;
mmsg_vector++;
skbuff_vector++;
The verify_header() < 0 path skips that via continue, so the freed skb
is left in skbuff_vector[] and the cursors do not advance. The next
iteration reads the same slot, gets the freed skb, and frees it again,
producing a refcount underflow / use-after-free in the RX path.
Discard the slot the same way the other paths do before continuing.
Only transports whose verify_header() can return negative are affected:
GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),
so any peer on such a transport can trigger it without authentication.
Fixes: 49da7e64f33e ("High Performance UML Vector Network Driver")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
| -rw-r--r-- | arch/um/drivers/vector_kern.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c index 2cc90055499a..8a70b3a62553 100644 --- a/arch/um/drivers/vector_kern.c +++ b/arch/um/drivers/vector_kern.c @@ -995,6 +995,9 @@ static int vector_mmsg_rx(struct vector_private *vp, int budget) */ dev_kfree_skb_irq(skb); vp->estats.rx_encaps_errors++; + (*skbuff_vector) = NULL; + mmsg_vector++; + skbuff_vector++; continue; } if (header_check > 0) { |