kernel/linux.git/net/xfrm, branch v7.0.10

xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete

2026-05-14T13:31:05+00:00

commit 14acf9652e5690de3c7486c6db5fb8dafd0a32a3 upstream. KASAN reproduces a slab-use-after-free in __xfrm_state_delete()'s hlist_del_rcu calls under syzkaller load on linux-6.12.y stable (reproduced on 6.12.47, also reachable via the same code path on torvalds/master and on the ipsec tree). Nine unique signatures cluster in the xfrm_state lifecycle, the load-bearing one being: BUG: KASAN: slab-use-after-free in __hlist_del include/linux/list.h:990 [inline] BUG: KASAN: slab-use-after-free in hlist_del_rcu include/linux/rculist.h:516 [inline] BUG: KASAN: slab-use-after-free in __xfrm_state_delete net/xfrm/xfrm_state.c Write of size 8 at addr ffff8881198bcb70 by task kworker/u8:9/435 Workqueue: netns cleanup_net Call Trace: __hlist_del / hlist_del_rcu __xfrm_state_delete xfrm_state_delete xfrm_state_flush xfrm_state_fini ops_exit_list cleanup_net The other observed signatures hit the same slab object from __xfrm_state_lookup, xfrm_alloc_spi, __xfrm_state_insert and an OOB write variant of __xfrm_state_delete, all on the byseq/byspi hash chains. __xfrm_state_delete() guards its byseq and byspi unhashes with value-based predicates: if (x->km.seq) hlist_del_rcu(&x->byseq); if (x->id.spi) hlist_del_rcu(&x->byspi); while everywhere else in the file (e.g. state_cache, state_cache_input) the safer hlist_unhashed() check is used. xfrm_alloc_spi() sets x->id.spi = newspi inside xfrm_state_lock and then immediately inserts into byspi, but a path that observes x->id.spi != 0 outside of xfrm_state_lock can still skip-or-hit the byspi unhash inconsistently with whether x is actually on the list. The same holds for x->km.seq versus byseq, and the bydst/bysrc unhashes have no predicate at all, so a second __xfrm_state_delete() on the same object writes through LIST_POISON pprev. The defensive change here: - Use hlist_del_init_rcu() instead of hlist_del_rcu() on bydst, bysrc, byseq and byspi so a second deletion is a no-op rather than a write through LIST_POISON pprev. The byseq/byspi nodes are already initialised in xfrm_state_alloc(). - Test hlist_unhashed() rather than the value predicate for byseq/byspi, so the unhash decision tracks list state rather than mutable scalar fields. Empirical verification: applied this patch on top of v6.12.47, rebuilt, and re-ran the same syzkaller harness for 1h16m on a previously-crashy configuration that produced ~100 hits each of slab-use-after-free Read in xfrm_alloc_spi / Read in __xfrm_state_lookup / Write in __xfrm_state_delete. After the patch, 7.1M execs across 32 VMs at ~1550 exec/sec produced zero xfrm_state UAF/OOB hits. /proc/slabinfo confirms the xfrm_state slab is actively allocated and freed during the run (~143 KiB resident), so the fuzzer is still exercising those code paths -- they just no longer crash. Reproduction: - Linux 6.12.47 x86_64 + KASAN_GENERIC + KASAN_INLINE + KCOV - syzkaller @ 746545b8b1e4c3a128db8652b340d3df90ce61db - 32 QEMU/KVM VMs x 2 vCPU on AWS c5.metal bare metal - 9 unique signatures collected in ~9h, all within xfrm_state lifecycle Fixes: fe9f1d8779cb ("xfrm: add state hashtable keyed by seq") Fixes: 7b4dc3600e48 ("[XFRM]: Do not add a state whose SPI is zero to the SPI hash.") Reported-by: Michal Kosiorek Tested-by: Michal Kosiorek Cc: stable@vger.kernel.org Signed-off-by: Michal Kosiorek Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman

xfrm: provide message size for XFRM_MSG_MAPPING

2026-05-14T13:31:05+00:00

commit 28465227c80fe417b4013c432be1f3737cb9f9a3 upstream. The compat 64=>32 translation path handles XFRM_MSG_MAPPING, but xfrm_msg_min[] does not provide the native payload size for this message type. Add the missing XFRM_MSG_MAPPING entry so compat translation can size and translate mapping notifications correctly. Fixes: 5461fc0c8d9f ("xfrm/compat: Add 64=>32-bit messages translator") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Ruijie Li Signed-off-by: Ren Wei Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman

xfrm_user: fix info leak in build_report()

2026-04-07T08:36:38+00:00

struct xfrm_user_report is a __u8 proto field followed by a struct xfrm_selector which means there is three "empty" bytes of padding, but the padding is never zeroed before copying to userspace. Fix that up by zeroing the structure before setting individual member variables. Cc: stable Cc: Steffen Klassert Cc: Herbert Xu Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Simon Horman Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Steffen Klassert

xfrm_user: fix info leak in build_mapping()

2026-04-07T08:36:37+00:00

struct xfrm_usersa_id has a one-byte padding hole after the proto field, which ends up never getting set to zero before copying out to userspace. Fix that up by zeroing out the whole structure before setting individual variables. Fixes: 3a2dfbe8acb1 ("xfrm: Notify changes in UDP encapsulation via netlink") Cc: Steffen Klassert Cc: Herbert Xu Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Simon Horman Assisted-by: gregkh_clanker_t1000 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Steffen Klassert

xfrm: fix refcount leak in xfrm_migrate_policy_find

2026-04-07T08:24:23+00:00

syzkaller reported a memory leak in xfrm_policy_alloc: BUG: memory leak unreferenced object 0xffff888114d79000 (size 1024): comm "syz.1.17", pid 931 ... xfrm_policy_alloc+0xb3/0x4b0 net/xfrm/xfrm_policy.c:432 The root cause is a double call to xfrm_pol_hold_rcu() in xfrm_migrate_policy_find(). The lookup function already returns a policy with held reference, making the second call redundant. Remove the redundant xfrm_pol_hold_rcu() call to fix the refcount imbalance and prevent the memory leak. Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes: 563d5ca93e88 ("xfrm: switch migrate to xfrm_policy_lookup_bytype") Signed-off-by: Kotlyarov Mihail Reviewed-by: Florian Westphal Signed-off-by: Steffen Klassert

xfrm: hold dev ref until after transport_finish NF_HOOK

2026-04-07T08:12:40+00:00

After async crypto completes, xfrm_input_resume() calls dev_put() immediately on re-entry before the skb reaches transport_finish. The skb->dev pointer is then used inside NF_HOOK and its okfn, which can race with device teardown. Remove the dev_put from the async resumption entry and instead drop the reference after the NF_HOOK call in transport_finish, using a saved device pointer since NF_HOOK may consume the skb. This covers NF_DROP, NF_QUEUE and NF_STOLEN paths that skip the okfn. For non-transport exits (decaps, gro, drop) and secondary async return points, release the reference inline when async is set. Suggested-by: Florian Westphal Fixes: acf568ee859f ("xfrm: Reinject transport-mode packets through tasklet") Cc: stable@vger.kernel.org Signed-off-by: Qi Tang Signed-off-by: Steffen Klassert

xfrm: Wait for RCU readers during policy netns exit

2026-04-07T08:12:40+00:00

xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables. Fixes: e1e551bc5630 ("xfrm: policy: prepare policy_bydst hash for rcu lookups") Signed-off-by: Steffen Klassert Reviewed-by: Florian Westphal

xfrm: account XFRMA_IF_ID in aevent size calculation

2026-03-30T05:53:55+00:00

xfrm_get_ae() allocates the reply skb with xfrm_aevent_msgsize(), then build_aevent() appends attributes including XFRMA_IF_ID when x->if_id is set. xfrm_aevent_msgsize() does not include space for XFRMA_IF_ID. For states with if_id, build_aevent() can fail with -EMSGSIZE and hit BUG_ON(err < 0) in xfrm_get_ae(), turning a malformed netlink interaction into a kernel panic. Account XFRMA_IF_ID in the size calculation unconditionally and replace the BUG_ON with normal error unwinding. Fixes: 7e6526404ade ("xfrm: Add a new lookup key to match xfrm interfaces.") Reported-by: Keenan Dong Signed-off-by: Keenan Dong Signed-off-by: Steffen Klassert

xfrm: clear trailing padding in build_polexpire()

2026-03-30T05:47:32+00:00

build_expire() clears the trailing padding bytes of struct xfrm_user_expire after setting the hard field via memset_after(), but the analogous function build_polexpire() does not do this for struct xfrm_user_polexpire. The padding bytes after the __u8 hard field are left uninitialized from the heap allocation, and are then sent to userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners, leaking kernel heap memory contents. Add the missing memset_after() call, matching build_expire(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Yasuaki Torimaru Reviewed-by: Simon Horman Reviewed-by: Breno Leitao Signed-off-by: Steffen Klassert

Merge tag 'ipsec-2026-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec

2026-03-24T14:16:28+00:00

Steffen Klassert says: ==================== pull request (net): ipsec 2026-03-23 1) Add missing extack for XFRMA_SA_PCPU in add_acquire and allocspi. From Sabrina Dubroca. 2) Fix the condition on x->pcpu_num in xfrm_sa_len by using the proper check. From Sabrina Dubroca. 3) Call xdo_dev_state_delete during state update to properly cleanup the xdo device state. From Sabrina Dubroca. 4) Fix a potential skb leak in espintcp when async crypto is used. From Sabrina Dubroca. 5) Validate inner IPv4 header length in IPTFS payload to avoid parsing malformed packets. From Roshan Kumar. 6) Fix skb_put() panic on non-linear skb during IPTFS reassembly. From Fernando Fernandez Mancera. 7) Silence various sparse warnings related to RCU, state, and policy handling. From Sabrina Dubroca. 8) Fix work re-schedule race after cancel in xfrm_nat_keepalive_net_fini(). From Hyunwoo Kim. 9) Prevent policy_hthresh.work from racing with netns teardown by using a proper cleanup mechanism. From Minwoo Ra. 10) Validate that the family of the source and destination addresses match in pfkey_send_migrate(). From Eric Dumazet. 11) Only publish mode_data after the clone is setup in the IPTFS receive path. This prevents leaving x->mode_data pointing at freed memory on error. From Paul Moses. Please pull or let me know if there are problems. ipsec-2026-03-23 * tag 'ipsec-2026-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec: xfrm: iptfs: only publish mode_data after clone setup af_key: validate families in pfkey_send_migrate() xfrm: prevent policy_hthresh.work from racing with netns teardown xfrm: Fix work re-schedule after cancel in xfrm_nat_keepalive_net_fini() xfrm: avoid RCU warnings around the per-netns netlink socket xfrm: add rcu_access_pointer to silence sparse warning for xfrm_input_afinfo xfrm: policy: silence sparse warning in xfrm_policy_unregister_afinfo xfrm: policy: fix sparse warnings in xfrm_policy_{init,fini} xfrm: state: silence sparse warnings during netns exit xfrm: remove rcu/state_hold from xfrm_state_lookup_spi_proto xfrm: state: add xfrm_state_deref_prot to state_by* walk under lock xfrm: state: fix sparse warnings around XFRM_STATE_INSERT xfrm: state: fix sparse warnings in xfrm_state_init xfrm: state: fix sparse warnings on xfrm_state_hold_rcu xfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly xfrm: iptfs: validate inner IPv4 header length in IPTFS payload esp: fix skb leak with espintcp and async crypto xfrm: call xdo_dev_state_delete during state update xfrm: fix the condition on x->pcpu_num in xfrm_sa_len xfrm: add missing extack for XFRMA_SA_PCPU in add_acquire and allocspi ==================== Link: https://patch.msgid.link/20260323083440.2741292-1-steffen.klassert@secunet.com Signed-off-by: Paolo Abeni