317ef02b0d5cbd19d445294fed91453c7f970fc3.c fixed by commit a2d859e3fc97e79d907761550dbc03ff1b36479c

[JohnD Oracle]

317ef02b0d5cbd19d445294fed91453c7f970fc3.c fixed by commit
a2d859e3fc97e79d907761550dbc03ff1b36479c



strace shows this activity ;

#strace ./test-scpt

socket(AF_INET6, SOCK_STREAM, IPPROTO_SCTP) = 3
setsockopt(3, SOL_SCTP, 0x76 /* SCTP_??? */, "\0\0\0\0\7\0\0\0", 8) = 0
setsockopt(3, SOL_SCTP, 0x64 /* SCTP_??? */,
"\n\0N#\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\0\0\0\0", 28) = 0
setsockopt(3, SOL_SCTP, 0x75 /* SCTP_??? */, "\0\0\0\0\0\0\4\20", 8) = 0
connect(3, {sa_family=AF_INET6, sin6_port=htons(20003),
inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, 28) = 0
setsockopt(3, SOL_SCTP, 0x77 /* SCTP_??? */,
"\0\0\0\0;\0)\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
734


CPU: 0 PID: 1358 Comm: skbuff-panic Not tainted
5.4.17-2136.301.0.el7uek.x86_64 #2
task: ffff880078bb5a00 task.stack: ffffc900006d8000
RIP: 0010:skb_panic+0x66/0x68
RSP: 0018:ffffc900006dbcf8 EFLAGS: 00010246
RAX: 0000000000000086 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff88007e816938 RDI: ffff88007e816938
[ RBP: ffffc900006dbd18 R08: 00000000fffffffe R09: 00000000000001f6
R10: 0000000000000005 R11: 00000000000001f5 R12: ffff880078512d00
R13: 0000000000000052 R14: ffff88007827fc00 R15: 0000000000000070
FS: 00007f80be10a740(0000) GS:ffff88007e800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000208c0000 CR3: 000000007937c000 CR4: 00000000000006f0
Call Trace:
skb_put+0x4c/0x4c
sctp_addto_chunk+0x59/0xb0 [sctp]
sctp_make_strreset_req+0x166/0x180 [sctp]
sctp_send_reset_streams+0x14d/0x300 [sctp]
sctp_setsockopt.part.21+0x101f/0x1720 [sctp]
sctp_setsockopt+0x99/0xb0 [sctp]
sock_common_setsockopt+0x1a/0x1c
SyS_setsockopt+0x86/0xe6
+0x79/0x1ae
entry_SYSCALL_64_after_hwframe+0x151/0x0
RIP: 0033:0x7f80bdc21be9


I am not familar with any of the sctp subsystem. It was found running
the syzkaller fuzzing test suite.

If there is a more appropriate place to report this I can do that too.
This test fails on just about every 4.x and 5.x kernel. It is not
unique to 5.4.


Thank you.

John.



===

// gcc -o test-sctp 317ef02b0d5cbd19d445294fed91453c7f970fc3.c

// autogenerated by syzkaller (https://github.com/google/syzkaller)
// 317ef02b0d5cbd19d445294fed91453c7f970fc3.c



#define _GNU_SOURCE

#include <arpa/inet.h>
#include <endian.h>
#include <fcntl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <sched.h>

#include <linux/genetlink.h>
#include <linux/if_addr.h>
#include <linux/if_link.h>
#include <linux/in6.h>
#include <linux/neighbour.h>
#include <linux/net.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/veth.h>

struct nlmsg {
char* pos;
int nesting;
struct nlattr* nested[8];
char buf[1024];
};

static struct nlmsg nlmsg;

static void netlink_init(struct nlmsg* nlmsg, int typ, int flags,
const void* data, int size)
{
memset(nlmsg, 0, sizeof(*nlmsg));
struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf;
hdr->nlmsg_type = typ;
hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
memcpy(hdr + 1, data, size);
nlmsg->pos = (char*)(hdr + 1) + NLMSG_ALIGN(size);
}

static void netlink_attr(struct nlmsg* nlmsg, int typ, const void* data,
int size)
{
struct nlattr* attr = (struct nlattr*)nlmsg->pos;
attr->nla_len = sizeof(*attr) + size;
attr->nla_type = typ;
memcpy(attr + 1, data, size);
nlmsg->pos += NLMSG_ALIGN(attr->nla_len);
}

static int netlink_send_ext(struct nlmsg* nlmsg, int sock, uint16_t reply_type,
int* reply_len)
{
if (nlmsg->pos > nlmsg->buf + sizeof(nlmsg->buf) || nlmsg->nesting)
exit(1);
struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf;
hdr->nlmsg_len = nlmsg->pos - nlmsg->buf;
struct sockaddr_nl addr;
memset(&addr, 0, sizeof(addr));
addr.nl_family = AF_NETLINK;
printf ("sending : %d\n", hdr->nlmsg_len);
unsigned n = sendto(sock, nlmsg->buf, hdr->nlmsg_len, 0,
(struct sockaddr*)&addr, sizeof(addr));
if (n != hdr->nlmsg_len)
exit(1);
n = recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0);
if (hdr->nlmsg_type == NLMSG_DONE) {
*reply_len = 0;
return 0;
}
if (n < sizeof(struct nlmsghdr))
exit(1);
if (reply_len && hdr->nlmsg_type == reply_type) {
*reply_len = n;
return 0;
}
if (n < sizeof(struct nlmsghdr) + sizeof(struct nlmsgerr))
exit(1);
if (hdr->nlmsg_type != NLMSG_ERROR)
exit(1);
return -((struct nlmsgerr*)(hdr + 1))->error;
}

static int netlink_send(struct nlmsg* nlmsg, int sock)
{
return netlink_send_ext(nlmsg, sock, 0, NULL);
}

static int netlink_next_msg(struct nlmsg* nlmsg, unsigned int offset,
unsigned int total_len)
{
struct nlmsghdr* hdr = (struct nlmsghdr*)(nlmsg->buf + offset);
if (offset == total_len || offset + hdr->nlmsg_len > total_len)
return -1;
return hdr->nlmsg_len;
}

static void netlink_device_change(struct nlmsg* nlmsg, int sock,
const char* name, bool up, const char* master,
const void* mac, int macsize,
const char* new_name)
{
struct ifinfomsg hdr;
memset(&hdr, 0, sizeof(hdr));
if (up)
hdr.ifi_flags = hdr.ifi_change = IFF_UP;
hdr.ifi_index = if_nametoindex(name);
netlink_init(nlmsg, RTM_NEWLINK, 0, &hdr, sizeof(hdr));
if (new_name)
netlink_attr(nlmsg, IFLA_IFNAME, new_name, strlen(new_name));
if (master) {
int ifindex = if_nametoindex(master);
netlink_attr(nlmsg, IFLA_MASTER, &ifindex, sizeof(ifindex));
}
if (macsize)
netlink_attr(nlmsg, IFLA_ADDRESS, mac, macsize);
int err = netlink_send(nlmsg, sock);
(void)err;
}

const int kInitNetNsFd = 239;

#define DEVLINK_FAMILY_NAME "devlink"

#define DEVLINK_CMD_PORT_GET 5
#define DEVLINK_CMD_RELOAD 37
#define DEVLINK_ATTR_BUS_NAME 1
#define DEVLINK_ATTR_DEV_NAME 2
#define DEVLINK_ATTR_NETDEV_NAME 7
#define DEVLINK_ATTR_NETNS_FD 138

static int netlink_devlink_id_get(struct nlmsg* nlmsg, int sock)
{
struct genlmsghdr genlhdr;
struct nlattr* attr;
int err, n;
uint16_t id = 0;
memset(&genlhdr, 0, sizeof(genlhdr));
genlhdr.cmd = CTRL_CMD_GETFAMILY;
netlink_init(nlmsg, GENL_ID_CTRL, 0, &genlhdr, sizeof(genlhdr));
netlink_attr(nlmsg, CTRL_ATTR_FAMILY_NAME, DEVLINK_FAMILY_NAME,
strlen(DEVLINK_FAMILY_NAME) + 1);
err = netlink_send_ext(nlmsg, sock, GENL_ID_CTRL, &n);
if (err) {
return -1;
}
attr = (struct nlattr*)(nlmsg->buf + NLMSG_HDRLEN +
NLMSG_ALIGN(sizeof(genlhdr)));
for (; (char*)attr < nlmsg->buf + n;
attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
if (attr->nla_type == CTRL_ATTR_FAMILY_ID) {
id = *(uint16_t*)(attr + 1);
break;
}
}
if (!id) {
return -1;
}
recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); /* recv ack */
return id;
}

static void netlink_devlink_netns_move(const char* bus_name,
const char* dev_name, int netns_fd)
{
struct genlmsghdr genlhdr;
int sock;
int id, err;
sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
if (sock == -1)
exit(1);
id = netlink_devlink_id_get(&nlmsg, sock);
if (id == -1)
goto error;
memset(&genlhdr, 0, sizeof(genlhdr));
genlhdr.cmd = DEVLINK_CMD_RELOAD;
netlink_init(&nlmsg, id, 0, &genlhdr, sizeof(genlhdr));
netlink_attr(&nlmsg, DEVLINK_ATTR_BUS_NAME, bus_name, strlen(bus_name) + 1);
netlink_attr(&nlmsg, DEVLINK_ATTR_DEV_NAME, dev_name, strlen(dev_name) + 1);
netlink_attr(&nlmsg, DEVLINK_ATTR_NETNS_FD, &netns_fd, sizeof(netns_fd));
err = netlink_send(&nlmsg, sock);
if (err) {
}
error:
close(sock);
}

static struct nlmsg nlmsg2;

static void initialize_devlink_ports(const char* bus_name, const char* dev_name,
const char* netdev_prefix)
{
struct genlmsghdr genlhdr;
int len, total_len, id, err, offset;
uint16_t netdev_index;
int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
if (sock == -1)
exit(1);
int rtsock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (rtsock == -1)
exit(1);
id = netlink_devlink_id_get(&nlmsg, sock);
if (id == -1)
goto error;
memset(&genlhdr, 0, sizeof(genlhdr));
genlhdr.cmd = DEVLINK_CMD_PORT_GET;
netlink_init(&nlmsg, id, NLM_F_DUMP, &genlhdr, sizeof(genlhdr));
netlink_attr(&nlmsg, DEVLINK_ATTR_BUS_NAME, bus_name, strlen(bus_name) + 1);
netlink_attr(&nlmsg, DEVLINK_ATTR_DEV_NAME, dev_name, strlen(dev_name) + 1);
err = netlink_send_ext(&nlmsg, sock, id, &total_len);
if (err) {
goto error;
}
offset = 0;
netdev_index = 0;
while ((len = netlink_next_msg(&nlmsg, offset, total_len)) != -1) {
struct nlattr* attr = (struct nlattr*)(nlmsg.buf + offset + NLMSG_HDRLEN +
NLMSG_ALIGN(sizeof(genlhdr)));
for (; (char*)attr < nlmsg.buf + offset + len;
attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) {
if (attr->nla_type == DEVLINK_ATTR_NETDEV_NAME) {
char* port_name;
char netdev_name[IFNAMSIZ];
port_name = (char*)(attr + 1);
snprintf(netdev_name, sizeof(netdev_name), "%s%d", netdev_prefix,
netdev_index);
netlink_device_change(&nlmsg2, rtsock, port_name, true, 0, 0, 0,
netdev_name);
break;
}
}
offset += len;
netdev_index++;
}
error:
close(rtsock);
close(sock);
}

static void initialize_devlink_pci(void)
{
int netns = open("/proc/self/ns/net", O_RDONLY);
if (netns == -1)
exit(1);
int ret = setns(kInitNetNsFd, 0);
if (ret == -1)
exit(1);
netlink_devlink_netns_move("pci", "0000:00:10.0", netns);
ret = setns(netns, 0);
if (ret == -1)
exit(1);
close(netns);
initialize_devlink_ports("pci", "0000:00:10.0", "netpci");
}

uint64_t r[1] = {0xffffffffffffffff};

int main(void)
{
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 3ul, 0x32ul, -1, 0);
intptr_t res = 0;
res = syscall(__NR_socket, 0xaul, 0x80000000000001ul, 0x84ul);
if (res != -1)
r[0] = res;
*(uint32_t*)0x20444ff8 = 0;
*(uint32_t*)0x20444ffc = 7;
syscall(__NR_setsockopt, r[0], 0x84ul, 0x76ul, 0x20444ff8ul, 8ul);
*(uint16_t*)0x20cf6fe4 = 0xa;
*(uint16_t*)0x20cf6fe6 = htobe16(0x4e23);
*(uint32_t*)0x20cf6fe8 = htobe32(0);
*(uint64_t*)0x20cf6fec = htobe64(0);
*(uint64_t*)0x20cf6ff4 = htobe64(1);
*(uint32_t*)0x20cf6ffc = 0;
syscall(__NR_setsockopt, r[0], 0x84ul, 0x64ul, 0x20cf6fe4ul, 0x1cul);
*(uint32_t*)0x20107ff8 = 0;
*(uint32_t*)0x20107ffc = 0x10040000;
syscall(__NR_setsockopt, r[0], 0x84ul, 0x75ul, 0x20107ff8ul, 8ul);
*(uint16_t*)0x208c0000 = 0xa;
*(uint16_t*)0x208c0002 = htobe16(0x4e23);
*(uint32_t*)0x208c0004 = htobe32(0);
*(uint64_t*)0x208c0008 = htobe64(0);
*(uint64_t*)0x208c0010 = htobe64(1);
*(uint32_t*)0x208c0018 = 0;
syscall(__NR_connect, r[0], 0x208c0000ul, 0x1cul);
*(uint32_t*)0x2081e000 = 0;
*(uint16_t*)0x2081e004 = 0x3b;
*(uint16_t*)0x2081e006 = 0x29;
*(uint16_t*)0x2081e008 = 0;
syscall(__NR_setsockopt, r[0], 0x84ul, 0x77ul, 0x2081e000ul, 0x2deul);
return 0;
}



=======




I can confirm


commit a2d859e3fc97e79d907761550dbc03ff1b36479c
Author: Eiichi Tsukata <eiichi....@nutanix.com>
Date: Wed Oct 13 17:27:29 2021 -0300

sctp: account stream padding length for reconf chunk

resolves my panic for 5.4.LTS wrt to

// autogenerated by syzkaller (https://github.com/google/syzkaller)
// 317ef02b0d5cbd19d445294fed91453c7f970fc3.c




---

JD