[syzbot] KASAN: use-after-free Read in cipso_v4_doi_add

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 26d657410983 MAINTAINERS: Update entry for the Stratix10 f..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110cb258b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=1de5da8af5c2277d
dashboard link: https://syzkaller.appspot.com/bug?extid=93dba5b91f0fed312cbd
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+93dba5...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in cipso_v4_doi_search net/ipv4/cipso_ipv4.c:363 [inline]
BUG: KASAN: use-after-free in cipso_v4_doi_add+0x4e0/0x7c0 net/ipv4/cipso_ipv4.c:420
Read of size 4 at addr ffff88803f6a5a00 by task syz-executor.3/14359

CPU: 1 PID: 14359 Comm: syz-executor.3 Not tainted 5.15.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106
print_address_description+0x66/0x3e0 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report+0x19a/0x1f0 mm/kasan/report.c:459
cipso_v4_doi_search net/ipv4/cipso_ipv4.c:363 [inline]
cipso_v4_doi_add+0x4e0/0x7c0 net/ipv4/cipso_ipv4.c:420
smk_cipso_doi+0x2d3/0x580 security/smack/smackfs.c:706
smk_write_doi+0x1ab/0x270 security/smack/smackfs.c:1615
vfs_write+0x327/0xe90 fs/read_write.c:592
ksys_write+0x18f/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f31447cba39
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3141d41188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f31448cef60 RCX: 00007f31447cba39
RDX: 0000000000000014 RSI: 0000000020000640 RDI: 0000000000000003
RBP: 00007f3144825c5f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd5bc3df9f R14: 00007f3141d41300 R15: 0000000000022000

Allocated by task 14339:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
____kasan_kmalloc+0xdc/0x110 mm/kasan/common.c:513
kasan_kmalloc include/linux/kasan.h:264 [inline]
kmem_cache_alloc_trace+0x9f/0x310 mm/slub.c:3233
kmalloc include/linux/slab.h:591 [inline]
smk_cipso_doi+0x200/0x580 security/smack/smackfs.c:696
smk_write_doi+0x1ab/0x270 security/smack/smackfs.c:1615
vfs_write+0x327/0xe90 fs/read_write.c:592
ksys_write+0x18f/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 14339:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4c/0x80 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0x10d/0x150 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1700 [inline]
slab_free_freelist_hook+0x129/0x1a0 mm/slub.c:1725
slab_free mm/slub.c:3483 [inline]
kfree+0xcf/0x2f0 mm/slub.c:4543
smk_cipso_doi+0x3b7/0x580
smk_write_doi+0x1ab/0x270 security/smack/smackfs.c:1615
vfs_write+0x327/0xe90 fs/read_write.c:592
ksys_write+0x18f/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88803f6a5a00
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes inside of
64-byte region [ffff88803f6a5a00, ffff88803f6a5a40)
The buggy address belongs to the page:
page:ffffea0000fda940 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3f6a5
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea0000866240 000000170000000d ffff888011041640
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 6522, ts 209857791495, free_ts 209857731843
prep_new_page mm/page_alloc.c:2424 [inline]
get_page_from_freelist+0x779/0xa30 mm/page_alloc.c:4153
__alloc_pages+0x255/0x580 mm/page_alloc.c:5375
alloc_slab_page mm/slub.c:1763 [inline]
allocate_slab+0xcc/0x4d0 mm/slub.c:1900
new_slab mm/slub.c:1963 [inline]
___slab_alloc+0x41e/0xc40 mm/slub.c:2994
__slab_alloc mm/slub.c:3081 [inline]
slab_alloc_node mm/slub.c:3172 [inline]
kmem_cache_alloc_node_trace+0x2c4/0x350 mm/slub.c:3256
kmalloc_node include/linux/slab.h:609 [inline]
kzalloc_node include/linux/slab.h:732 [inline]
__get_vm_area_node+0x13a/0x2f0 mm/vmalloc.c:2416
__vmalloc_node_range+0xe3/0x890 mm/vmalloc.c:3010
__vmalloc_node mm/vmalloc.c:3069 [inline]
vzalloc+0x75/0x80 mm/vmalloc.c:3139
alloc_counters+0xd2/0x800 net/ipv6/netfilter/ip6_tables.c:817
copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:839 [inline]
get_entries net/ipv6/netfilter/ip6_tables.c:1041 [inline]
do_ip6t_get_ctl+0xf57/0x1f40 net/ipv6/netfilter/ip6_tables.c:1672
nf_getsockopt+0x2ab/0x2d0 net/netfilter/nf_sockopt.c:116
ipv6_getsockopt+0x4ae/0x3f30 net/ipv6/ipv6_sockglue.c:1486
__sys_getsockopt+0x29f/0x560 net/socket.c:2220
__do_sys_getsockopt net/socket.c:2235 [inline]
__se_sys_getsockopt net/socket.c:2232 [inline]
__x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2232
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1338 [inline]
free_pcp_prepare+0xc29/0xd20 mm/page_alloc.c:1389
free_unref_page_prepare mm/page_alloc.c:3315 [inline]
free_unref_page+0x7d/0x580 mm/page_alloc.c:3394
__vunmap+0x926/0xa70 mm/vmalloc.c:2621
copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:884 [inline]
get_entries net/ipv6/netfilter/ip6_tables.c:1041 [inline]
do_ip6t_get_ctl+0x186d/0x1f40 net/ipv6/netfilter/ip6_tables.c:1672
nf_getsockopt+0x2ab/0x2d0 net/netfilter/nf_sockopt.c:116
ipv6_getsockopt+0x4ae/0x3f30 net/ipv6/ipv6_sockglue.c:1486
__sys_getsockopt+0x29f/0x560 net/socket.c:2220
__do_sys_getsockopt net/socket.c:2235 [inline]
__se_sys_getsockopt net/socket.c:2232 [inline]
__x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2232
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
ffff88803f6a5900: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88803f6a5980: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88803f6a5a00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffff88803f6a5a80: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88803f6a5b00: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


---
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[Tetsuo Handa]

syzbot is reporting UAF at cipso_v4_doi_search() [1], for smk_cipso_doi()
is calling kfree() without removing from the cipso_v4_doi_list list after
netlbl_cfg_cipsov4_map_add() returned an error. We need to use
netlbl_cfg_cipsov4_del() in order to remove from the list and wait for
RCU grace period before kfree().

Link: https://syzkaller.appspot.com/bug?extid=93dba5b91f0fed312cbd [1]
Reported-by: syzbot <syzbot+93dba5...@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
Fixes: 6c2e8ac0953fccdd ("netlabel: Update kernel configuration API")
---
security/smack/smackfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 3a75d2a8f517..83b90442f963 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -714,7 +714,7 @@ static void smk_cipso_doi(void)
if (rc != 0) {
printk(KERN_WARNING "%s:%d map add rc = %d\n",
__func__, __LINE__, rc);
- kfree(doip);
+ netlbl_cfg_cipsov4_del(doip->doi, &nai);
return;
}
}
--
2.18.4

[Casey Schaufler]

On 10/19/2021 4:27 AM, Tetsuo Handa wrote:
> syzbot is reporting UAF at cipso_v4_doi_search() [1], for smk_cipso_doi()
> is calling kfree() without removing from the cipso_v4_doi_list list after
> netlbl_cfg_cipsov4_map_add() returned an error. We need to use
> netlbl_cfg_cipsov4_del() in order to remove from the list and wait for
> RCU grace period before kfree().
>
> Link: https://syzkaller.appspot.com/bug?extid=93dba5b91f0fed312cbd [1]
> Reported-by: syzbot <syzbot+93dba5...@syzkaller.appspotmail.com>
> Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
> Fixes: 6c2e8ac0953fccdd ("netlabel: Update kernel configuration API")

Added to smack-next. Thank you.