During fuzz testing, the following issue was discovered:

BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x598/0x2a30 _copy_to_iter+0x598/0x2a30 __skb_datagram_iter+0x168/0x1060 skb_copy_datagram_iter+0x5b/0x220 netlink_recvmsg+0x362/0x1700 sock_recvmsg+0x2dc/0x390 __sys_recvfrom+0x381/0x6d0 __x64_sys_recvfrom+0x130/0x200 x64_sys_call+0x32c8/0x3cc0 do_syscall_64+0xd8/0x1c0 entry_SYSCALL_64_after_hwframe+0x79/0x81

Uninit was stored to memory at: copy_to_user_state_extra+0xcc1/0x1e00 dump_one_state+0x28c/0x5f0 xfrm_state_walk+0x548/0x11e0 xfrm_dump_sa+0x1e0/0x840 netlink_dump+0x943/0x1c40 __netlink_dump_start+0x746/0xdb0 xfrm_user_rcv_msg+0x429/0xc00 netlink_rcv_skb+0x613/0x780 xfrm_netlink_rcv+0x77/0xc0 netlink_unicast+0xe90/0x1280 netlink_sendmsg+0x126d/0x1490 __sock_sendmsg+0x332/0x3d0 ____sys_sendmsg+0x863/0xc30 ___sys_sendmsg+0x285/0x3e0 __x64_sys_sendmsg+0x2d6/0x560 x64_sys_call+0x1316/0x3cc0 do_syscall_64+0xd8/0x1c0 entry_SYSCALL_64_after_hwframe+0x79/0x81

Uninit was created at: __kmalloc+0x571/0xd30 attach_auth+0x106/0x3e0 xfrm_add_sa+0x2aa0/0x4230 xfrm_user_rcv_msg+0x832/0xc00 netlink_rcv_skb+0x613/0x780 xfrm_netlink_rcv+0x77/0xc0 netlink_unicast+0xe90/0x1280 netlink_sendmsg+0x126d/0x1490 __sock_sendmsg+0x332/0x3d0 ____sys_sendmsg+0x863/0xc30 ___sys_sendmsg+0x285/0x3e0 __x64_sys_sendmsg+0x2d6/0x560 x64_sys_call+0x1316/0x3cc0 do_syscall_64+0xd8/0x1c0 entry_SYSCALL_64_after_hwframe+0x79/0x81

Bytes 328-379 of 732 are uninitialized Memory access of size 732 starts at ffff88800e18e000 Data copied to user address 00007ff30f48aff0

CPU: 2 PID: 18167 Comm: syz-executor.0 Not tainted 6.8.11 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014

Fixes copying of xfrm algorithms where some random data of the structure fields can end up in userspace. Padding in structures may be filled with random (possibly sensitve) data and should never be given directly to user-space.

A similar issue was resolved in the commit 8222d5910dae ("xfrm: Zero padding when dumping algos and encap")

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: c7a5899eb26e ("xfrm: redact SA secret with lockdown confidentiality") Cc: stable@vger.kernel.org Co-developed-by: Boris Tonofa b.tonofa@ideco.ru Signed-off-by: Boris Tonofa b.tonofa@ideco.ru Signed-off-by: Petr Vaganov p.vaganov@ideco.ru --- v3: Corrected commit description "This patch fixes copying..." to "Fixes copying..." according to accepted rules of Linux kernel commits, as suggested by Markus Elfring elfring@users.sourceforge.net. v2: Fixed typo in sizeof(sizeof(ap->alg_name) expression. The third argument for the strscpy_pad macro was chosen by analogy with those in other functions of this file - as did commit 8222d5910dae ("xfrm: Zero padding when dumping algos and encap"). I still think it would be better to leave the strscpy_pad() macro with three arguments in this patch, mainly so that it would be consistent with the existing similar code in this module. Regarding strncpy() above, we don't think it is a real issue since the uncopied parts should be already padded with zeroes by nla_reserve().

net/xfrm/xfrm_user.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 55f039ec3d59..0083faabe8be 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1098,7 +1098,9 @@ static int copy_to_user_auth(struct xfrm_algo_auth *auth, struct sk_buff *skb) if (!nla) return -EMSGSIZE; ap = nla_data(nla); - memcpy(ap, auth, sizeof(struct xfrm_algo_auth)); + strscpy_pad(ap->alg_name, auth->alg_name, sizeof(ap->alg_name)); + ap->alg_key_len = auth->alg_key_len; + ap->alg_trunc_len = auth->alg_trunc_len; if (redact_secret && auth->alg_key_len) memset(ap->alg_key, 0, (auth->alg_key_len + 7) / 8); else