In ipcomp_alloc_scratches, if the vmalloc fails, there leaves an oudated pointer in *per_cpu_ptr(scratches, i). However, in the error handling of ipcomp_init_state, if ipcomp_alloc_scratches fails, it will invoke ipcomp_free_scratches directly. This functio will vfree the per_cpu_ptr pointer. If the pointer points to an invalid memory, the kernel crashes.

Fix this by moving the assignment of per_cpu_ptr point before return.

Call Trace: ipcomp_free_scratches+0xbc/0x160 net/xfrm/xfrm_ipcomp.c:203 ipcomp_free_data net/xfrm/xfrm_ipcomp.c:312 [inline] ipcomp_init_state+0x77c/0xa40 net/xfrm/xfrm_ipcomp.c:364 ipcomp6_init_state+0xc2/0x700 net/ipv6/ipcomp6.c:154 __xfrm_init_state+0x995/0x15c0 net/xfrm/xfrm_state.c:2648 xfrm_init_state+0x1a/0x70 net/xfrm/xfrm_state.c:2675 pfkey_msg2xfrm_state net/key/af_key.c:1287 [inline] pfkey_add+0x1a64/0x2cd0 net/key/af_key.c:1504 pfkey_process+0x685/0x7e0 net/key/af_key.c:2837 pfkey_sendmsg+0x43a/0x820 net/key/af_key.c:3676 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:723

Reported-by: syzbot+b9cfd1cc5d57ee0a09ab@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Fixes: 6fccab671f2f ("ipsec: ipcomp - Merge IPComp impl") Signed-off-by: Dongliang Mu mudongliangabcd@gmail.com --- net/xfrm/xfrm_ipcomp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c index cb40ff0ff28d..01dbec70dfba 100644 --- a/net/xfrm/xfrm_ipcomp.c +++ b/net/xfrm/xfrm_ipcomp.c @@ -223,9 +223,9 @@ static void * __percpu *ipcomp_alloc_scratches(void) void *scratch;

scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i)); + *per_cpu_ptr(scratches, i) = scratch; if (!scratch) return NULL; - *per_cpu_ptr(scratches, i) = scratch; }

return scratches;