Описание
In the Linux kernel, the following vulnerability has been resolved: xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx This patch is inspired by the check[1] from sashiko. It says when overflow happens, the address of cq to be published is invalid. Actually the severer thing is the whole process of publishing the address of cq in this particular case is not right: it should truely publish the address and advance the cached_prod in cq as long as it reads descriptors from txq. The following is the full analysis. xsk_drop_skb() is called in three places, which all discard a partially built multi-buffer skb:
- xsk_build_skb() -EOVERFLOW error path: packet exceeds MAX_SKB_FRAGS
- __xsk_generic_xmit() post-loop cleanup: an invalid descriptor in the TX ring prevents the partial packet from completing
- xsk_release(): socket close while xs->skb holds an incomplete packet
In all three cases, the TX descriptors for the already-processed frags
have been consumed from the TX ring (xskq_cons_release), and CQ slots
have been reserved. However, xsk_drop_skb() calls xsk_consume_skb()
which cancels the CQ reservations via xsk_cq_cancel_locked(). Since
the buffer addresses never appear in the completion queue, userspace
permanently loses track of these buffers.
Fix this by letting consume_skb() trigger the existing xsk_destruct_skb
destructor, which already submits buffer addresses to the CQ via
xsk_cq_submit_addr_locked().
Note that cancelling the descriptors back to the TX ring (via
xskq_cons_cancel_n) is not a appropriate option because an oversized
packet that always exceeds MAX_SKB_FRAGS would be retried indefinitely,
which is an obviously deadlock bug in the TX path.
Also move the desc->addr assignment in xsk_build_skb() above the
overflow check so that the current descriptor's address is recorded
before a potential -EOVERFLOW jump to free_err, consistent with the
zerocopy path in xsk_build_skb_zerocopy().
[1]: https://lore.kernel.org/all/20260425041726.85FB3C2BCB2@smtp.kernel.org/
A flaw was found in the Linux kernel's AF_XDP (Address Family eXpress Data Path) subsystem. When handling multi-buffer transmissions, thexsk_drop_skb()function incorrectly cancels completion queue (CQ) reservations without submitting buffer addresses to the CQ. This leads to a buffer leak where userspace permanently loses track of these buffers, potentially causing resource exhaustion and affecting system stability.
Дополнительная информация
Статус:
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx This patch is inspired by the check[1] from sashiko. It says when overflow happens, the address of cq to be published is invalid. Actually the severer thing is the whole process of publishing the address of cq in this particular case is not right: it should truely publish the address and advance the cached_prod in cq as long as it reads descriptors from txq. The following is the full analysis. xsk_drop_skb() is called in three places, which all discard a partially built multi-buffer skb: 1) xsk_build_skb() -EOVERFLOW error path: packet exceeds MAX_SKB_FRAGS 2) __xsk_generic_xmit() post-loop cleanup: an invalid descriptor in the TX ring prevents the partial packet from completing 3) xsk_release(): socket close while xs->skb holds an incomplete packet In all three cases, the TX descriptors for the already-processed frags have been consumed from the TX r...
In the Linux kernel, the following vulnerability has been resolved: xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx This patch is inspired by the check[1] from sashiko. It says when overflow happens, the address of cq to be published is invalid. Actually the severer thing is the whole process of publishing the address of cq in this particular case is not right: it should truely publish the address and advance the cached_prod in cq as long as it reads descriptors from txq. The following is the full analysis. xsk_drop_skb() is called in three places, which all discard a partially built multi-buffer skb: 1) xsk_build_skb() -EOVERFLOW error path: packet exceeds MAX_SKB_FRAGS 2) __xsk_generic_xmit() post-loop cleanup: an invalid descriptor in the TX ring prevents the partial packet from completing 3) xsk_release(): socket close while xs->skb holds an incomplete packet In all three cases, the TX descriptors for the already-processed frags have been consumed from the
In the Linux kernel, the following vulnerability has been resolved: x ...
In the Linux kernel, the following vulnerability has been resolved: xsk: fix buffer leak in xsk_drop_skb() for AF_XDP multi-buffer Tx This patch is inspired by the check[1] from sashiko. It says when overflow happens, the address of cq to be published is invalid. Actually the severer thing is the whole process of publishing the address of cq in this particular case is not right: it should truely publish the address and advance the cached_prod in cq as long as it reads descriptors from txq. The following is the full analysis. xsk_drop_skb() is called in three places, which all discard a partially built multi-buffer skb: 1) xsk_build_skb() -EOVERFLOW error path: packet exceeds MAX_SKB_FRAGS 2) __xsk_generic_xmit() post-loop cleanup: an invalid descriptor in the TX ring prevents the partial packet from completing 3) xsk_release(): socket close while xs->skb holds an incomplete packet In all three cases, the TX descriptors for the already-processed frags have been consumed from t...
5.5 Medium
CVSS3