From: Jason Xing <kernelxing@tencent.com> mainline inclusion from mainline-v7.1-rc3 commit 203cee647f551abc87b992045cd920b117ff990a category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/17327 CVE: CVE-2026-74559 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In copy mode TX, xsk_skb_destructor_set_addr() stores the 64-bit descriptor address into skb_shinfo(skb)->destructor_arg (void *) via a uintptr_t cast: skb_shinfo(skb)->destructor_arg = (void *)((uintptr_t)addr | 0x1UL); On 32-bit architectures uintptr_t is 32 bits, so the upper 32 bits of the descriptor address are silently dropped. In XDP_ZEROCOPY unaligned mode the chunk offset is encoded in bits 48-63 of the descriptor address (XSK_UNALIGNED_BUF_OFFSET_SHIFT = 48), meaning the offset is lost entirely. The completion queue then returns a truncated address to userspace, making buffer recycling impossible. Fix this by handling the 32-bit case directly in xsk_skb_destructor_set_addr(): when !CONFIG_64BIT, allocate an xsk_addrs struct (the same path already used for multi-descriptor SKBs) to store the full u64 address. The existing tagged-pointer logic in xsk_skb_destructor_is_addr() stays unchanged: slab pointers returned from kmem_cache_zalloc() are always word-aligned and therefore have bit 0 clear, which correctly identifies them as a struct pointer rather than an inline tagged address on every architecture. Factor the shared kmem_cache_zalloc + destructor_arg assignment into __xsk_addrs_alloc() and add a wrapper xsk_addrs_alloc() that handles the inline-to-list upgrade (is_addr check + get_addr + num_descs = 1). The three former open-coded kmem_cache_zalloc call sites now reduce to a single call each. Propagate the -ENOMEM from xsk_skb_destructor_set_addr() through xsk_skb_init_misc() so the caller can clean up the skb via kfree_skb() before skb->destructor is installed. The overhead is one extra kmem_cache_zalloc per first descriptor on 32-bit only; 64-bit builds are completely unchanged. Closes: https://lore.kernel.org/all/20260419045824.D9E5EC2BCAF@smtp.kernel.org/ Fixes: 0ebc27a4c67d ("xsk: avoid data corruption on cq descriptor number") Signed-off-by: Jason Xing <kernelxing@tencent.com> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com> Link: https://patch.msgid.link/20260502200722.53960-9-kerneljasonxing@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Conflicts: net/xdp/xsk.c [Commit c30d084960cf backport without READ_ONCE() on sk->sk_priority.] Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com> --- net/xdp/xsk.c | 86 ++++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 55 insertions(+), 31 deletions(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index ca25327..f5af40d 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -540,9 +540,42 @@ static u64 xsk_skb_destructor_get_addr(struct sk_buff *skb) return (u64)((uintptr_t)skb_shinfo(skb)->destructor_arg & ~0x1UL); } -static void xsk_skb_destructor_set_addr(struct sk_buff *skb, u64 addr) +static struct xsk_addrs *__xsk_addrs_alloc(struct sk_buff *skb, u64 addr) { - skb_shinfo(skb)->destructor_arg = (void *)((uintptr_t)addr | 0x1UL); + struct xsk_addrs *xsk_addr; + + xsk_addr = kmem_cache_zalloc(xsk_tx_generic_cache, GFP_KERNEL); + if (unlikely(!xsk_addr)) + return NULL; + + xsk_addr->addrs[0] = addr; + skb_shinfo(skb)->destructor_arg = (void *)xsk_addr; + return xsk_addr; +} + +static struct xsk_addrs *xsk_addrs_alloc(struct sk_buff *skb) +{ + struct xsk_addrs *xsk_addr; + + if (!xsk_skb_destructor_is_addr(skb)) + return (struct xsk_addrs *)skb_shinfo(skb)->destructor_arg; + + xsk_addr = __xsk_addrs_alloc(skb, xsk_skb_destructor_get_addr(skb)); + if (likely(xsk_addr)) + xsk_addr->num_descs = 1; + return xsk_addr; +} + +static int xsk_skb_destructor_set_addr(struct sk_buff *skb, u64 addr) +{ + if (IS_ENABLED(CONFIG_64BIT)) { + skb_shinfo(skb)->destructor_arg = (void *)((uintptr_t)addr | 0x1UL); + return 0; + } + + if (unlikely(!__xsk_addrs_alloc(skb, addr))) + return -ENOMEM; + return 0; } static void xsk_inc_num_desc(struct sk_buff *skb) @@ -612,14 +645,20 @@ static void xsk_destruct_skb(struct sk_buff *skb) sock_wfree(skb); } -static void xsk_skb_init_misc(struct sk_buff *skb, struct xdp_sock *xs, +static int xsk_skb_init_misc(struct sk_buff *skb, struct xdp_sock *xs, u64 addr) { + int err; + + err = xsk_skb_destructor_set_addr(skb, addr); + if (unlikely(err)) + return err; + skb->dev = xs->dev; skb->priority = xs->sk.sk_priority; skb->mark = READ_ONCE(xs->sk.sk_mark); skb->destructor = xsk_destruct_skb; - xsk_skb_destructor_set_addr(skb, addr); + return 0; } static void xsk_consume_skb(struct sk_buff *skb) @@ -668,18 +707,9 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, } else { struct xsk_addrs *xsk_addr; - if (xsk_skb_destructor_is_addr(skb)) { - xsk_addr = kmem_cache_zalloc(xsk_tx_generic_cache, - GFP_KERNEL); - if (!xsk_addr) - return ERR_PTR(-ENOMEM); - - xsk_addr->num_descs = 1; - xsk_addr->addrs[0] = xsk_skb_destructor_get_addr(skb); - skb_shinfo(skb)->destructor_arg = (void *)xsk_addr; - } else { - xsk_addr = (struct xsk_addrs *)skb_shinfo(skb)->destructor_arg; - } + xsk_addr = xsk_addrs_alloc(skb); + if (!xsk_addr) + return ERR_PTR(-ENOMEM); /* in case of -EOVERFLOW that could happen below, * xsk_consume_skb() will release this node as whole skb @@ -760,19 +790,10 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, struct page *page; u8 *vaddr; - if (xsk_skb_destructor_is_addr(skb)) { - xsk_addr = kmem_cache_zalloc(xsk_tx_generic_cache, - GFP_KERNEL); - if (!xsk_addr) { - err = -ENOMEM; - goto free_err; - } - - xsk_addr->num_descs = 1; - xsk_addr->addrs[0] = xsk_skb_destructor_get_addr(skb); - skb_shinfo(skb)->destructor_arg = (void *)xsk_addr; - } else { - xsk_addr = (struct xsk_addrs *)skb_shinfo(skb)->destructor_arg; + xsk_addr = xsk_addrs_alloc(skb); + if (!xsk_addr) { + err = -ENOMEM; + goto free_err; } if (unlikely(nr_frags == (MAX_SKB_FRAGS - 1) && xp_mb_desc(desc))) { @@ -797,8 +818,11 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, } } - if (!xs->skb) - xsk_skb_init_misc(skb, xs, desc->addr); + if (!xs->skb) { + err = xsk_skb_init_misc(skb, xs, desc->addr); + if (unlikely(err)) + goto free_err; + } xsk_inc_num_desc(skb); return skb; -- 2.9.5