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[129.132.161.179]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490bc39eb04sm409212995e9.6.2026.06.08.07.45.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 07:45:05 -0700 (PDT) From: Zijing Yin To: Steffen Klassert , Herbert Xu Cc: Zijing Yin , "David S . Miller" , Eric Dumazet , Paolo Abeni , Ido Schimmel , Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH net v2] net: af_key: initialize alg_key_len for IPComp states Date: Mon, 8 Jun 2026 07:44:41 -0700 Message-ID: <20260608144453.3553219-1-yzjaurora@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit pfkey_msg2xfrm_state() handles the IPComp (SADB_X_SATYPE_IPCOMP) case by allocating x->calg and copying only the algorithm name: x->calg = kmalloc_obj(*x->calg); if (!x->calg) { err = -ENOMEM; goto out; } strcpy(x->calg->alg_name, a->name); x->props.calgo = sa->sadb_sa_encrypt; Unlike the authentication (x->aalg) and encryption (x->ealg) branches of the same function, the compression branch never initializes calg->alg_key_len. IPComp carries no key and the allocation only reserves sizeof(struct xfrm_algo) (i.e. no room for a key), so the field is left containing uninitialized slab data. calg->alg_key_len is later used as a length by xfrm_algo_clone() when an IPComp state is cloned during XFRM_MSG_MIGRATE: xfrm_state_migrate() xfrm_state_clone_and_setup() x->calg = xfrm_algo_clone(orig->calg); kmemdup(orig, xfrm_alg_len(orig)); where xfrm_alg_len() returns sizeof(*alg) + (alg_key_len + 7) / 8. With a non-zero garbage alg_key_len, kmemdup() reads past the end of the 68-byte calg object. Adding an IPComp SA via PF_KEY and then migrating it triggers (net-next, KASAN, init_on_alloc=0): BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x44/0x60 Read of size 4164 at addr ff11000025a74980 by task diag2/9287 CPU: 3 UID: 0 PID: 9287 Comm: diag2 7.1.0-rc6-g903db046d557 #1 Call Trace: dump_stack_lvl+0x10e/0x1f0 print_report+0xf7/0x600 kasan_report+0xe4/0x120 kasan_check_range+0x105/0x1b0 __asan_memcpy+0x23/0x60 kmemdup_noprof+0x44/0x60 xfrm_state_migrate+0x70a/0x1da0 xfrm_migrate+0x753/0x18a0 xfrm_do_migrate+0xb47/0xf10 xfrm_user_rcv_msg+0x411/0xb50 netlink_rcv_skb+0x158/0x420 xfrm_netlink_rcv+0x71/0x90 netlink_unicast+0x584/0x850 netlink_sendmsg+0x8b0/0xdc0 ____sys_sendmsg+0x9f7/0xb90 ___sys_sendmsg+0x134/0x1d0 __sys_sendmsg+0x16d/0x220 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 9287: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 pfkey_add+0x2652/0x2ea0 pfkey_process+0x6d0/0x830 pfkey_sendmsg+0x42c/0x850 __sys_sendto+0x461/0x4b0 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ff11000025a74980 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes inside of allocated 68-byte region [ff11000025a74980, ff11000025a749c4) Depending on the uninitialized value the same field can instead request an oversized kmemdup() allocation and make the migration clone fail. The XFRM netlink path is not affected: verify_one_alg() rejects an XFRMA_ALG_COMP attribute shorter than xfrm_alg_len(), so a calg added via XFRM_MSG_NEWSA is always self-consistent. Initialize calg->alg_key_len to 0, matching the aalg/ealg branches. Fixes: 80c9abaabf42 ("[XFRM]: Extension for dynamic update of endpoint address(es)") Cc: stable@vger.kernel.org Signed-off-by: Zijing Yin --- v2: fix some typos. Link to v1: https://lore.kernel.org/all/20260607210119.2437752-1-yzjaurora@gmail.com/ net/key/af_key.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/key/af_key.c b/net/key/af_key.c index 9cffeef18..3216f897a 100644 --- a/net/key/af_key.c +++ b/net/key/af_key.c @@ -1218,6 +1218,7 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct net *net, goto out; } strcpy(x->calg->alg_name, a->name); + x->calg->alg_key_len = 0; x->props.calgo = sa->sadb_sa_encrypt; } else { int keysize = 0; -- 2.43.0