From: Xin Long <lucien.xin@gmail.com> mainline inclusion from mainline-v5.6 commit d1d17a359ce6901545c075d7401c10179d9cedfd category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/17032 CVE: CVE-2026-68426 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Xiumei found a panic in esp offload: BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 RIP: 0010:esp_output_done+0x101/0x160 [esp4] Call Trace: ? esp_output+0x180/0x180 [esp4] cryptd_aead_crypt+0x4c/0x90 cryptd_queue_worker+0x6e/0xa0 process_one_work+0x1a7/0x3b0 worker_thread+0x30/0x390 ? create_worker+0x1a0/0x1a0 kthread+0x112/0x130 ? kthread_flush_work_fn+0x10/0x10 ret_from_fork+0x35/0x40 It was caused by that skb secpath is used in esp_output_done() after it's been released elsewhere. The tx path for esp offload is: __dev_queue_xmit()-> validate_xmit_skb_list()-> validate_xmit_xfrm()-> esp_xmit()-> esp_output_tail()-> aead_request_set_callback(esp_output_done) <--[1] crypto_aead_encrypt() <--[2] In [1], .callback is set, and in [2] it will trigger the worker schedule, later on a kernel thread will call .callback(esp_output_done), as the call trace shows. But in validate_xmit_xfrm(): skb_list_walk_safe(skb, skb2, nskb) { ... err = x->type_offload->xmit(x, skb2, esp_features); [esp_xmit] ... } When the err is -EINPROGRESS, which means this skb2 will be enqueued and later gets encrypted and sent out by .callback later in a kernel thread, skb2 should be removed fromt skb chain. Otherwise, it will get processed again outside validate_xmit_xfrm(), which could release skb secpath, and cause the panic above. This patch is to remove the skb from the chain when it's enqueued in cryptd_wq. While at it, remove the unnecessary 'if (!skb)' check. Fixes: 3dca3f38cfb8 ("xfrm: Separate ESP handling from segmentation for GRO packets.") Reported-by: Xiumei Mu <xmu@redhat.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com> Conflicts: net/xfrm/xfrm_device.c [commit c3b18e0d9254 ("net: xfrm: use skb_list_walk_safe helper for gso segments") is not backport, which lead to conflicts; adapted to the 4.19-style do-while loop with goto skip_push: track the last retained segment in pskb and bridge pskb->next around segments stolen by async crypto, replacing the "if (!skb) return NULL" bail-out, preserving the upstream semantics on the target's control flow] Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/xfrm/xfrm_device.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c index 8a9f02997067..e63da1ff17bf 100644 --- a/net/xfrm/xfrm_device.c +++ b/net/xfrm/xfrm_device.c @@ -28,7 +28,7 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur int err; unsigned long flags; struct xfrm_state *x; - struct sk_buff *skb2; + struct sk_buff *skb2, *pskb = NULL; struct softnet_data *sd; netdev_features_t esp_features = features; struct xfrm_offload *xo = xfrm_offload(skb); @@ -119,14 +119,14 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur } else { if (skb == skb2) skb = nskb; - - if (!skb) - return NULL; + else + pskb->next = nskb; goto skip_push; } skb_push(skb2, skb2->data - skb_mac_header(skb2)); + pskb = skb2; skip_push: skb2 = nskb; -- 2.43.0