Hello, The following program causes use-after-free in pptp_connect and a leak of pptp call id:
// autogenerated by syzkaller (http://github.com/google/syzkaller) #include <syscall.h> #include <string.h> #include <stdint.h> #include <stdio.h> #include <sys/types.h> #include <sys/socket.h> #include <linux/in.h> #include <linux/in6.h> #include <linux/if.h> #include <linux/if_pppox.h> int main() { int fd = socket(PF_PPPOX, SOCK_STREAM, PX_PROTO_PPTP); struct sockaddr_pppox sa; sa.sa_family = AF_PPPOX; sa.sa_protocol = PX_PROTO_PPTP; sa.sa_addr.pptp.call_id = 0; sa.sa_addr.pptp.sin_addr.s_addr = 0; bind(fd, (struct sockaddr *)&sa, sizeof(sa)); int len = sizeof(sa); getsockname(fd, (struct sockaddr *)&sa, &len); printf("addr %d/%d\n", sa.sa_addr.pptp.call_id, sa.sa_addr.pptp.sin_addr.s_addr); int callid = sa.sa_addr.pptp.call_id; sa.sa_addr.pptp.call_id = 0; sa.sa_addr.pptp.sin_addr.s_addr = 0; bind(fd, (struct sockaddr *)&sa, sizeof(sa)); getsockname(fd, (struct sockaddr *)&sa, &len); printf("addr %d/%d\n", sa.sa_addr.pptp.call_id, sa.sa_addr.pptp.sin_addr.s_addr); close(fd); int cfd = socket(PF_PPPOX, SOCK_STREAM, PX_PROTO_PPTP); sa.sa_addr.pptp.call_id = callid; sa.sa_addr.pptp.sin_addr.s_addr = 0; connect(cfd, (struct sockaddr *)&sa, sizeof(sa)); } ================================================================== BUG: KASAN: use-after-free in pptp_connect+0xbdc/0xc00 at addr ffff88006a46d800 Read of size 2 by task a.out/7038 ============================================================================= BUG kmalloc-2048 (Not tainted): kasan: bad access detected ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in sk_prot_alloc+0x1a9/0x2c0 age=986682 cpu=2 pid=7009 [< none >] ___slab_alloc+0x489/0x4e0 mm/slub.c:2438 [< none >] __slab_alloc+0x4c/0x90 mm/slub.c:2467 [< inline >] slab_alloc_node mm/slub.c:2530 [< inline >] slab_alloc mm/slub.c:2572 [< none >] __kmalloc+0x299/0x330 mm/slub.c:3532 [< inline >] kmalloc include/linux/slab.h:463 [< none >] sk_prot_alloc+0x1a9/0x2c0 net/core/sock.c:1355 [< none >] sk_alloc+0x31/0x620 net/core/sock.c:1420 [< none >] pptp_create+0x23/0x2e0 drivers/net/ppp/pptp.c:570 [< none >] pppox_create+0xd3/0x1e0 drivers/net/ppp/pppox.c:121 [< none >] __sock_create+0x2f2/0x590 net/socket.c:1162 [< inline >] sock_create net/socket.c:1202 [< inline >] SYSC_socket net/socket.c:1232 [< none >] SyS_socket+0xd0/0x190 net/socket.c:1212 [< none >] tracesys_phase2+0x88/0x8d arch/x86/entry/entry_64.S:269 INFO: Freed in sk_destruct+0x317/0x420 age=986672 cpu=2 pid=7009 [< none >] __slab_free+0x1fc/0x320 mm/slub.c:2648 [< inline >] slab_free mm/slub.c:2803 [< none >] kfree+0x26a/0x290 mm/slub.c:3632 [< inline >] sk_prot_free net/core/sock.c:1392 [< none >] sk_destruct+0x317/0x420 net/core/sock.c:1468 [< none >] __sk_free+0x4f/0x1e0 net/core/sock.c:1476 [< none >] sk_free+0x13/0x20 net/core/sock.c:1487 [< inline >] sock_put include/net/sock.h:1624 [< none >] pptp_release+0x197/0x200 drivers/net/ppp/pptp.c:549 [< none >] sock_release+0x83/0x1a0 net/socket.c:571 [< none >] sock_close+0xd/0x20 net/socket.c:1022 [< none >] __fput+0x210/0x750 fs/file_table.c:208 [< none >] ____fput+0x9/0x10 fs/file_table.c:244 [< none >] task_work_run+0x132/0x200 kernel/task_work.c:115 [< inline >] exit_task_work include/linux/task_work.h:21 [< none >] do_exit+0x7fb/0x2be0 kernel/exit.c:748 [< none >] do_group_exit+0xf4/0x2f0 kernel/exit.c:878 [< inline >] SYSC_exit_group kernel/exit.c:889 [< none >] SyS_exit_group+0x18/0x20 kernel/exit.c:887 [< none >] tracesys_phase2+0x88/0x8d arch/x86/entry/entry_64.S:269 INFO: Slab 0xffffea0001a91a00 objects=13 used=6 fp=0xffff88006a46b7b0 flags=0x5fffc0000004080 INFO: Object 0xffff88006a46d388 @offset=21384 fp=0x (null) CPU: 0 PID: 7038 Comm: a.out Tainted: G B 4.4.0-rc4+ #6 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffff88006a468000 ffff88003284fba8 ffffffff82841227 ffff88003e804f00 ffff88003284fbd8 ffffffff81697d04 ffff88003e804f00 ffffea0001a91a00 ffff88006a46d388 ffff88006a46d388 ffff88003284fc00 ffffffff8169e3bf Call Trace: [<ffffffff816a10be>] __asan_report_load2_noabort+0x3e/0x40 mm/kasan/report.c:278 [< inline >] lookup_chan_dst drivers/net/ppp/pptp.c:123 [<ffffffff83a125dc>] pptp_connect+0xbdc/0xc00 drivers/net/ppp/pptp.c:446 [<ffffffff84aa82a2>] SYSC_connect+0x202/0x2a0 net/socket.c:1542 [<ffffffff84aaa769>] SyS_connect+0x9/0x10 net/socket.c:1523 [<ffffffff85b43ff8>] tracesys_phase2+0x88/0x8d arch/x86/entry/entry_64.S:269 ================================================================== On commit b9d85451ddd4e7f2d6280506f6fe7f1924356924 (Dec 11). -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
