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xsk: Fix fragment node deletion to prevent buffer leak

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After commit b692bf9a75 ("xsk: Get rid of xdp_buff_xsk::xskb_list_node"),
the list_node field is reused for both the xskb pool list and the buffer
free list, this causes a buffer leak as described below.

xp_free() checks if a buffer is already on the free list using
list_empty(&xskb->list_node). When list_del() is used to remove a node
from the xskb pool list, it doesn't reinitialize the node pointers.
This means list_empty() will return false even after the node has been
removed, causing xp_free() to incorrectly skip adding the buffer to the
free list.

Fix this by using list_del_init() instead of list_del() in all fragment
handling paths, this ensures the list node is reinitialized after removal,
allowing the list_empty() to work correctly.

Fixes: b692bf9a75 ("xsk: Get rid of xdp_buff_xsk::xskb_list_node")
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Nikhil P. Rao <nikhil.rao@amd.com>
Link: https://patch.msgid.link/20260225000456.107806-2-nikhil.rao@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Nikhil P. Rao 2026-02-25 00:00:26 +00:00 • committed by Jakub Kicinski
parent 6df0022b6c
commit 60abb0ac11
2 changed files with 4 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

6
include/net/xdp_sock_drv.h
View file

@ -122,7 +122,7 @@ static inline void xsk_buff_free(struct xdp_buff *xdp)
goto out;
list_for_each_entry_safe(pos, tmp, xskb_list, list_node) {
list_del(&pos->list_node);
list_del_init(&pos->list_node);
xp_free(pos);
}
@ -157,7 +157,7 @@ static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)
frag = list_first_entry_or_null(&xskb->pool->xskb_list,
struct xdp_buff_xsk, list_node);
if (frag) {
list_del(&frag->list_node);
list_del_init(&frag->list_node);
ret = &frag->xdp;
}
@ -168,7 +168,7 @@ static inline void xsk_buff_del_frag(struct xdp_buff *xdp)
{
struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
list_del(&xskb->list_node);
list_del_init(&xskb->list_node);
}
static inline struct xdp_buff *xsk_buff_get_head(struct xdp_buff *first)

2
net/xdp/xsk.c
View file

@ -186,7 +186,7 @@ static int xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
err = __xsk_rcv_zc(xs, pos, len, contd);
if (err)
goto err;
list_del(&pos->list_node);
list_del_init(&pos->list_node);
}
return 0;