[syzbot] [can?] KASAN: slab-use-after-free Read in j1939_xtp_rx_dat_one

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2c71fdf02a95 Merge tag 'drm-fixes-2024-04-09' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1147924d180000
kernel config: https://syzkaller.appspot.com/x/.config?x=285be8dd6baeb438
dashboard link: https://syzkaller.appspot.com/bug?extid=75ec36af46e2098f253c
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11ae00cb180000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-2c71fdf0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d7474aaf31a/vmlinux-2c71fdf0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/895428c29966/bzImage-2c71fdf0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+75ec36...@syzkaller.appspotmail.com

vcan0: j1939_xtp_rx_dat_one: 0xffff88802c9a1400: Data of RX-looped back packet (00 00 00 00 00 00 00) doesn't match TX data (00 63 67 72 6f 75 70)!
==================================================================
BUG: KASAN: slab-use-after-free in j1939_xtp_rx_dat_one+0xf2d/0xfb0 net/can/j1939/transport.c:1888
Read of size 1 at addr ffff88803c35394e by task syz-executor.0/6638

CPU: 1 PID: 6638 Comm: syz-executor.0 Not tainted 6.9.0-rc3-syzkaller-00023-g2c71fdf02a95 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc3/0x620 mm/kasan/report.c:488
kasan_report+0xd9/0x110 mm/kasan/report.c:601
j1939_xtp_rx_dat_one+0xf2d/0xfb0 net/can/j1939/transport.c:1888
j1939_xtp_rx_dat net/can/j1939/transport.c:1940 [inline]
j1939_tp_recv+0x7c5/0xf50 net/can/j1939/transport.c:2134
j1939_can_recv+0x78f/0xa70 net/can/j1939/main.c:112
deliver net/can/af_can.c:572 [inline]
can_rcv_filter+0x2a8/0x900 net/can/af_can.c:606
can_receive+0x320/0x5c0 net/can/af_can.c:663
can_rcv+0x1e0/0x280 net/can/af_can.c:687
__netif_receive_skb_one_core+0x1b1/0x1e0 net/core/dev.c:5538
__netif_receive_skb+0x1d/0x160 net/core/dev.c:5652
process_backlog+0x12f/0x6f0 net/core/dev.c:5981
__napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:6632
napi_poll net/core/dev.c:6701 [inline]
net_rx_action+0x9ad/0xf10 net/core/dev.c:6816
__do_softirq+0x218/0x922 kernel/softirq.c:554
invoke_softirq kernel/softirq.c:428 [inline]
__irq_exit_rcu kernel/softirq.c:633 [inline]
irq_exit_rcu+0xb9/0x120 kernel/softirq.c:645
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
sysvec_apic_timer_interrupt+0x95/0xb0 arch/x86/kernel/apic/apic.c:1043
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:preempt_count_add+0x1f/0x150 kernel/sched/core.c:5874
Code: 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 c7 c0 a0 0a 6b 94 55 48 ba 00 00 00 00 00 fc ff df 48 89 c1 53 83 e0 07 89 fb <48> c1 e9 03 83 c0 03 65 01 3d 7b ee a5 7e 0f b6 14 11 38 d0 7c 08
RSP: 0018:ffffc9000df47d10 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff946b0aa0
RDX: dffffc0000000000 RSI: ffffffff820230f6 RDI: 0000000000000001
RBP: ffff88802a87fa60 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: ffff888024238350
R13: ffff88802a87fa68 R14: 0000000000000000 R15: dffffc0000000000
mnt_get_write_access+0x20/0x300 fs/namespace.c:352
mnt_want_write+0x149/0x450 fs/namespace.c:410
filename_create+0x10d/0x530 fs/namei.c:3885
do_symlinkat+0xbf/0x310 fs/namei.c:4500
__do_sys_symlinkat fs/namei.c:4523 [inline]
__se_sys_symlinkat fs/namei.c:4520 [inline]
__x64_sys_symlinkat+0x97/0xc0 fs/namei.c:4520
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f35bd27d5e7
Code: 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0a 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc8ec53158 EFLAGS: 00000202 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007ffc8ec53220 RCX: 00007f35bd27d5e7
RDX: 00007f35bd2ca526 RSI: 00000000ffffff9c RDI: 00007ffc8ec53220
RBP: 0000000000000001 R08: 0000000000000017 R09: 00007ffc8ec52ea7
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
</TASK>

Allocated by task 6640:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:312 [inline]
__kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:338
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3798 [inline]
slab_alloc_node mm/slub.c:3845 [inline]
kmem_cache_alloc_node+0x177/0x340 mm/slub.c:3888
__alloc_skb+0x2b1/0x380 net/core/skbuff.c:658
alloc_skb include/linux/skbuff.h:1313 [inline]
alloc_skb_with_frags+0xe4/0x710 net/core/skbuff.c:6504
sock_alloc_send_pskb+0x7f1/0x980 net/core/sock.c:2795
sock_alloc_send_skb include/net/sock.h:1842 [inline]
j1939_sk_alloc_skb net/can/j1939/socket.c:878 [inline]
j1939_sk_send_loop net/can/j1939/socket.c:1142 [inline]
j1939_sk_sendmsg+0x6d4/0x1370 net/can/j1939/socket.c:1277
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_sendmsg+0x3cb/0x470 net/socket.c:768
splice_to_socket+0xab2/0x1040 fs/splice.c:889
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x19b/0x6d0 fs/splice.c:1164
splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0x17e/0x250 fs/splice.c:1233
do_sendfile+0xaa8/0xdb0 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x1da/0x220 fs/read_write.c:1348
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 24:
kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
poison_slab_object mm/kasan/common.c:240 [inline]
__kasan_slab_free+0x11d/0x1a0 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kmem_cache_free+0x12e/0x380 mm/slub.c:4344
kfree_skbmem+0x10e/0x200 net/core/skbuff.c:1159
__kfree_skb net/core/skbuff.c:1217 [inline]
kfree_skb_reason+0x13a/0x210 net/core/skbuff.c:1252
kfree_skb include/linux/skbuff.h:1262 [inline]
j1939_session_skb_drop_old net/can/j1939/transport.c:347 [inline]
j1939_xtp_rx_cts_one net/can/j1939/transport.c:1445 [inline]
j1939_xtp_rx_cts+0x619/0xf60 net/can/j1939/transport.c:1484
j1939_tp_cmd_recv net/can/j1939/transport.c:2072 [inline]
j1939_tp_recv+0x568/0xf50 net/can/j1939/transport.c:2144
j1939_can_recv+0x78f/0xa70 net/can/j1939/main.c:112
deliver net/can/af_can.c:572 [inline]
can_rcv_filter+0x2a8/0x900 net/can/af_can.c:606
can_receive+0x320/0x5c0 net/can/af_can.c:663
can_rcv+0x1e0/0x280 net/can/af_can.c:687
__netif_receive_skb_one_core+0x1b1/0x1e0 net/core/dev.c:5538
__netif_receive_skb+0x1d/0x160 net/core/dev.c:5652
process_backlog+0x12f/0x6f0 net/core/dev.c:5981
__napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:6632
napi_poll net/core/dev.c:6701 [inline]
net_rx_action+0x9ad/0xf10 net/core/dev.c:6816
__do_softirq+0x218/0x922 kernel/softirq.c:554

The buggy address belongs to the object at ffff88803c353900
which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 78 bytes inside of
freed 240-byte region [ffff88803c353900, ffff88803c3539f0)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3c352
head: order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff80000000840(slab|head|node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000840 ffff888019288780 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000
head: 00fff80000000840 ffff888019288780 0000000000000000 dead000000000001
head: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000
head: 00fff80000000001 ffffea0000f0d481 ffffea0000f0d4c8 00000000ffffffff
head: 0000000200000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x152820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 12, tgid 12 (kworker/u32:1), ts 292119497381, free_ts 291277043750
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
__alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page mm/slub.c:2175 [inline]
allocate_slab mm/slub.c:2338 [inline]
new_slab+0xcc/0x3a0 mm/slub.c:2391
___slab_alloc+0x66d/0x1790 mm/slub.c:3525
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3610
__slab_alloc_node mm/slub.c:3663 [inline]
slab_alloc_node mm/slub.c:3835 [inline]
kmem_cache_alloc+0x2e9/0x320 mm/slub.c:3852
skb_clone+0x190/0x3f0 net/core/skbuff.c:2063
can_send+0x56d/0xb40 net/can/af_can.c:260
j1939_send_one+0x299/0x360 net/can/j1939/main.c:357
j1939_tp_tx_dat net/can/j1939/transport.c:646 [inline]
j1939_session_tx_dat net/can/j1939/transport.c:838 [inline]
j1939_xtp_txnext_transmiter net/can/j1939/transport.c:900 [inline]
j1939_tp_txtimer+0xa8f/0x29e0 net/can/j1939/transport.c:1160
__run_hrtimer kernel/time/hrtimer.c:1692 [inline]
__hrtimer_run_queues+0x20c/0xcc0 kernel/time/hrtimer.c:1756
hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1773
__do_softirq+0x218/0x922 kernel/softirq.c:554
page last free pid 4682 tgid 4682 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1141 [inline]
free_unref_page_prepare+0x527/0xb10 mm/page_alloc.c:2347
free_unref_page+0x33/0x3c0 mm/page_alloc.c:2487
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x4e/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x192/0x1e0 mm/kasan/quarantine.c:286
__kasan_kmalloc+0x8a/0xb0 mm/kasan/common.c:378
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slub.c:3966 [inline]
__kmalloc+0x1f9/0x440 mm/slub.c:3979
kmalloc include/linux/slab.h:632 [inline]
kzalloc include/linux/slab.h:749 [inline]
tomoyo_encode2+0x100/0x3e0 security/tomoyo/realpath.c:45
tomoyo_encode+0x29/0x50 security/tomoyo/realpath.c:80
tomoyo_realpath_from_path+0x19d/0x720 security/tomoyo/realpath.c:283
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x273/0x450 security/tomoyo/file.c:822
tomoyo_path_unlink+0x92/0xe0 security/tomoyo/tomoyo.c:162
security_path_unlink+0x100/0x170 security/security.c:1857
do_unlinkat+0x55b/0x750 fs/namei.c:4396
__do_sys_unlink fs/namei.c:4447 [inline]
__se_sys_unlink fs/namei.c:4445 [inline]
__x64_sys_unlink+0xc7/0x110 fs/namei.c:4445
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88803c353800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88803c353880: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
>ffff88803c353900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88803c353980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
ffff88803c353a00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 90 nop
1: 90 nop
2: 90 nop
3: 90 nop
4: 90 nop
5: 90 nop
6: 90 nop
7: 90 nop
8: 90 nop
9: 90 nop
a: 90 nop
b: f3 0f 1e fa endbr64
f: 48 c7 c0 a0 0a 6b 94 mov $0xffffffff946b0aa0,%rax
16: 55 push %rbp
17: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
1e: fc ff df
21: 48 89 c1 mov %rax,%rcx
24: 53 push %rbx
25: 83 e0 07 and $0x7,%eax
28: 89 fb mov %edi,%ebx
* 2a: 48 c1 e9 03 shr $0x3,%rcx <-- trapping instruction
2e: 83 c0 03 add $0x3,%eax
31: 65 01 3d 7b ee a5 7e add %edi,%gs:0x7ea5ee7b(%rip) # 0x7ea5eeb3
38: 0f b6 14 11 movzbl (%rcx,%rdx,1),%edx
3c: 38 d0 cmp %dl,%al
3e: 7c 08 jl 0x48


---
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[Hillf Danton]

On Sat, 13 Apr 2024 23:27:33 -0700

> syzbot found the following issue on:
>
> HEAD commit: 2c71fdf02a95 Merge tag 'drm-fixes-2024-04-09' of https://g..
> git tree: upstream

> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11ae00cb180000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2c71fdf02a95

--- x/net/can/j1939/transport.c
+++ y/net/can/j1939/transport.c
@@ -2122,10 +2122,12 @@ static void j1939_tp_cmd_recv(struct j19
int j1939_tp_recv(struct j1939_priv *priv, struct sk_buff *skb)
{
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
+ int ret = 1;

if (!j1939_tp_im_involved_anydir(skcb) && !j1939_cb_is_broadcast(skcb))
return 0;

+ skb_get(skb);
switch (skcb->addr.pgn) {
case J1939_ETP_PGN_DAT:
skcb->addr.type = J1939_ETP;
@@ -2138,14 +2140,18 @@ int j1939_tp_recv(struct j1939_priv *pri
skcb->addr.type = J1939_ETP;
fallthrough;
case J1939_TP_PGN_CTL:
- if (skb->len < 8)
- return 0; /* Don't care. Nothing to extract here */
+ if (skb->len < 8) {
+ ret = 0; /* Don't care. Nothing to extract here */
+ break;
+ }

j1939_tp_cmd_recv(priv, skb);
break;
default:
- return 0; /* no problem */
+ ret = 0; /* no problem */
+ break;
}
+ kfree_skb(skb);
return 1; /* "I processed the message" */
}

--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+75ec36...@syzkaller.appspotmail.com

Tested on:

commit: 2c71fdf0 Merge tag 'drm-fixes-2024-04-09' of https://g..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=14ba600b180000

kernel config: https://syzkaller.appspot.com/x/.config?x=285be8dd6baeb438
dashboard link: https://syzkaller.appspot.com/bug?extid=75ec36af46e2098f253c
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=15c0ceb3180000

Note: testing is done by a robot and is best-effort only.