[syzbot] [tomoyo?] general protection fault in tomoyo_gc_thread

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f92f4749861b Merge tag 'clk-fixes-for-linus' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12fa2cdf980000
kernel config: https://syzkaller.appspot.com/x/.config?x=99a5586995ec03b2
dashboard link: https://syzkaller.appspot.com/bug?extid=bf6351831bc4f9148d98
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=12fc78f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b85403132ddc/disk-f92f4749.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/20613d034287/vmlinux-f92f4749.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d1ea80bf7e4e/bzImage-f92f4749.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bf6351...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 6044 Comm: GC for TOMOYO Not tainted 6.13.0-rc2-syzkaller-00031-gf92f4749861b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:tomoyo_collect_acl security/tomoyo/gc.c:511 [inline]
RIP: 0010:tomoyo_collect_entry security/tomoyo/gc.c:537 [inline]
RIP: 0010:tomoyo_gc_thread security/tomoyo/gc.c:619 [inline]
RIP: 0010:tomoyo_gc_thread+0x1ab/0x1390 security/tomoyo/gc.c:612
Code: 3b 5c 47 fd c6 45 18 ff 4c 89 ee bf 09 00 00 00 e8 8a f1 ff ff e8 25 5c 47 fd 48 89 d8 48 89 de 49 89 dd 48 c1 e8 03 83 e6 07 <42> 0f b6 0c 20 48 8d 43 07 48 89 c2 48 c1 ea 03 42 0f b6 14 22 40
RSP: 0018:ffffc90003367e78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8451e1ab
RDX: ffff888074e85a00 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff888143b02f00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000b8f R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888025b49b00
FS: 0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000028642000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:tomoyo_collect_acl security/tomoyo/gc.c:511 [inline]
RIP: 0010:tomoyo_collect_entry security/tomoyo/gc.c:537 [inline]
RIP: 0010:tomoyo_gc_thread security/tomoyo/gc.c:619 [inline]
RIP: 0010:tomoyo_gc_thread+0x1ab/0x1390 security/tomoyo/gc.c:612
Code: 3b 5c 47 fd c6 45 18 ff 4c 89 ee bf 09 00 00 00 e8 8a f1 ff ff e8 25 5c 47 fd 48 89 d8 48 89 de 49 89 dd 48 c1 e8 03 83 e6 07 <42> 0f b6 0c 20 48 8d 43 07 48 89 c2 48 c1 ea 03 42 0f b6 14 22 40
RSP: 0018:ffffc90003367e78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8451e1ab
RDX: ffff888074e85a00 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff888143b02f00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000b8f R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888025b49b00
FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b9c4865950 CR3: 0000000029aee000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 3b 5c 47 fd cmp -0x3(%rdi,%rax,2),%ebx
4: c6 45 18 ff movb $0xff,0x18(%rbp)
8: 4c 89 ee mov %r13,%rsi
b: bf 09 00 00 00 mov $0x9,%edi
10: e8 8a f1 ff ff call 0xfffff19f
15: e8 25 5c 47 fd call 0xfd475c3f
1a: 48 89 d8 mov %rbx,%rax
1d: 48 89 de mov %rbx,%rsi
20: 49 89 dd mov %rbx,%r13
23: 48 c1 e8 03 shr $0x3,%rax
27: 83 e6 07 and $0x7,%esi
* 2a: 42 0f b6 0c 20 movzbl (%rax,%r12,1),%ecx <-- trapping instruction
2f: 48 8d 43 07 lea 0x7(%rbx),%rax
33: 48 89 c2 mov %rax,%rdx
36: 48 c1 ea 03 shr $0x3,%rdx
3a: 42 0f b6 14 22 movzbl (%rdx,%r12,1),%edx
3f: 40 rex


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Tetsuo Handa]

tomoyo_try_to_gc() is called only when the ->is_deleted flag is set.
The ->is_deleted flag is set when a line in

delete $a_line_to_delete

format is written via the /sys/kernel/security/tomoyo/ interface.
But since I can't find the "delete " string within the syz reproducer,
tomoyo_try_to_gc() should not be called in the first place.

The syz reproducer is repeatedly opening /sys/kernel/security/tomoyo/manager
which in turn repeatedly triggers the gc thread. But unless the ->is_deleted
flag is set, gc has nothing to remove from the lists, and list corruption
cannot happen because list manipulation is serialized by tomoyo_policy_lock
mutex.

Therefore, currently I can't imagine that this report and "general protection
fault in tomoyo_check_acl (4)" and "BUG: corrupted list in tomoyo_try_to_gc"
are TOMOYO's bug; these look like a collateral victim caused by memory
corruption in somewhere else.

Anyway, let's try with lockdep annotation added.

#syz test

diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c
index 972664962e8f..25273d35e1b1 100644
--- a/security/tomoyo/common.c
+++ b/security/tomoyo/common.c
@@ -348,6 +348,7 @@ void tomoyo_init_policy_namespace(struct tomoyo_policy_namespace *ns)
INIT_LIST_HEAD(&ns->policy_list[idx]);
ns->profile_version = 20150505;
tomoyo_namespace_enabled = !list_empty(&tomoyo_namespace_list);
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add_tail_rcu(&ns->namespace_list, &tomoyo_namespace_list);
}

diff --git a/security/tomoyo/condition.c b/security/tomoyo/condition.c
index f8bcc083bb0d..f9e78deb51b2 100644
--- a/security/tomoyo/condition.c
+++ b/security/tomoyo/condition.c
@@ -427,6 +427,7 @@ static struct tomoyo_condition *tomoyo_commit_condition
if (!found) {
if (tomoyo_memory_ok(entry)) {
atomic_set(&entry->head.users, 1);
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add(&entry->head.list, &tomoyo_condition_list);
} else {
found = true;
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 3a7b0874cf44..b90728a6edc9 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -54,6 +54,7 @@ int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
if (error && !param->is_delete) {
entry = tomoyo_commit_ok(new_entry, size);
if (entry) {
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add_tail_rcu(&entry->list, list);
error = 0;
}
@@ -138,6 +139,7 @@ int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size,
if (error && !is_delete) {
entry = tomoyo_commit_ok(new_entry, size);
if (entry) {
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add_tail_rcu(&entry->list, list);
error = 0;
}
@@ -576,6 +578,7 @@ struct tomoyo_domain_info *tomoyo_assign_domain(const char *domainname,
entry = tomoyo_commit_ok(&e, sizeof(e));
if (entry) {
INIT_LIST_HEAD(&entry->acl_info_list);
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add_tail_rcu(&entry->list, &tomoyo_domain_list);
created = true;
}
diff --git a/security/tomoyo/gc.c b/security/tomoyo/gc.c
index 026e29ea3796..ef3ed4fc71ca 100644
--- a/security/tomoyo/gc.c
+++ b/security/tomoyo/gc.c
@@ -29,6 +29,8 @@ static LIST_HEAD(tomoyo_io_buffer_list);
/* Lock for protecting tomoyo_io_buffer_list. */
static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);

+static DEFINE_MUTEX(tomoyo_gc_mutex);
+
/**
* tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
*
@@ -392,8 +394,11 @@ static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
* tomoyo_domain_list). Also, synchronize_srcu() guarantees that the
* list element became no longer referenced by syscall users.
*/
+ struct list_head *head = element->prev;
+
__list_del_entry(element);
mutex_unlock(&tomoyo_policy_lock);
+ lockdep_assert_held(&tomoyo_gc_mutex);
synchronize_srcu(&tomoyo_ss);
/*
* However, there are two users which may still be using the list
@@ -470,7 +475,10 @@ static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
* exclusively executed by tomoyo_gc_mutex mutex.
* are true.
*/
+ lockdep_assert_held(&tomoyo_gc_mutex);
mutex_lock(&tomoyo_policy_lock);
+ printk("Reinjecting list=%px type=%d\n", element, type);
+ BUG_ON(element->prev != head);
list_add_rcu(element, element->prev);
}

@@ -612,7 +620,6 @@ static void tomoyo_collect_entry(void)
static int tomoyo_gc_thread(void *unused)
{
/* Garbage collector thread is exclusive. */
- static DEFINE_MUTEX(tomoyo_gc_mutex);

if (!mutex_trylock(&tomoyo_gc_mutex))
goto out;
diff --git a/security/tomoyo/memory.c b/security/tomoyo/memory.c
index 1b570bde7a3b..e70c33576349 100644
--- a/security/tomoyo/memory.c
+++ b/security/tomoyo/memory.c
@@ -123,6 +123,7 @@ struct tomoyo_group *tomoyo_get_group(struct tomoyo_acl_param *param,
if (entry) {
INIT_LIST_HEAD(&entry->member_list);
atomic_set(&entry->head.users, 1);
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add_tail_rcu(&entry->head.list, list);
group = entry;
found = true;
@@ -176,6 +177,7 @@ const struct tomoyo_path_info *tomoyo_get_name(const char *name)
memmove((char *) ptr->entry.name, name, len);
atomic_set(&ptr->head.users, 1);
tomoyo_fill_path_info(&ptr->entry);
+ lockdep_assert_held(&tomoyo_policy_lock);
list_add_tail(&ptr->head.list, head);
} else {
kfree(ptr);
@@ -199,7 +201,9 @@ void __init tomoyo_mm_init(void)
for (idx = 0; idx < TOMOYO_MAX_HASH; idx++)
INIT_LIST_HEAD(&tomoyo_name_list[idx]);
tomoyo_kernel_namespace.name = "<kernel>";
+ mutex_lock(&tomoyo_policy_lock);
tomoyo_init_policy_namespace(&tomoyo_kernel_namespace);
+ mutex_unlock(&tomoyo_policy_lock);
tomoyo_kernel_domain.ns = &tomoyo_kernel_namespace;
INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
tomoyo_kernel_domain.domainname = tomoyo_get_name("<kernel>");

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in tomoyo_init_request_info

Oops: general protection fault, probably for non-canonical address 0xdffffc000000000a: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000050-0x0000000000000057]
CPU: 1 UID: 0 PID: 6698 Comm: syz.2.57 Not tainted 6.13.0-rc3-syzkaller-g8faabc041a00-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
RIP: 0010:tomoyo_init_request_info+0x6f/0x370 security/tomoyo/util.c:1028
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 98 02 00 00 48 8d 7d 50 48 89 6b 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 5d 02 00 00 48 8d 7b 4b 44 0f b6 6d
RSP: 0018:ffffc90003eef790 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffffc90003eef808 RCX: 0000000000000000
RDX: 000000000000000a RSI: ffffffff8452e107 RDI: 0000000000000050
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc90003eef808 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000048000 R14: ffff8880760cf040 R15: 0000000000000004
FS: 00007f79ac9fe6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000000000000008 CR3: 000000001dea8000 CR4: 00000000003526f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>

tomoyo_check_open_permission+0x27a/0x3c0 security/tomoyo/file.c:769
tomoyo_file_open+0x6b/0x90 security/tomoyo/tomoyo.c:334
security_file_open+0x84/0x1e0 security/security.c:3105
do_dentry_open+0x57e/0x1ea0 fs/open.c:928
vfs_open+0x82/0x3f0 fs/open.c:1075
do_open fs/namei.c:3828 [inline]
path_openat+0x1e6a/0x2d60 fs/namei.c:3987
do_filp_open+0x20c/0x470 fs/namei.c:4014
do_sys_openat2+0x17a/0x1e0 fs/open.c:1402
do_sys_open fs/open.c:1417 [inline]
__do_sys_openat fs/open.c:1433 [inline]
__se_sys_openat fs/open.c:1428 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1428
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f79ad785d19
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f79ac9fe038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f79ad975fa0 RCX: 00007f79ad785d19
RDX: 0000000000040000 RSI: 0000000020000040 RDI: ffffffffffffff9c
RBP: 00007f79ad801a20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f79ad975fa0 R15: 00007ffe8d39dad8

</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---

RIP: 0010:tomoyo_init_request_info+0x6f/0x370 security/tomoyo/util.c:1028
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 98 02 00 00 48 8d 7d 50 48 89 6b 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 5d 02 00 00 48 8d 7b 4b 44 0f b6 6d
RSP: 0018:ffffc90003eef790 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffffc90003eef808 RCX: 0000000000000000
RDX: 000000000000000a RSI: ffffffff8452e107 RDI: 0000000000000050
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc90003eef808 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000048000 R14: ffff8880760cf040 R15: 0000000000000004
FS: 00007f79ac9fe6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000000c006f48000 CR3: 000000001dea8000 CR4: 00000000003526f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):

0: 48 89 fa mov %rdi,%rdx
3: 48 c1 ea 03 shr $0x3,%rdx
7: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
b: 0f 85 98 02 00 00 jne 0x2a9
11: 48 8d 7d 50 lea 0x50(%rbp),%rdi
15: 48 89 6b 10 mov %rbp,0x10(%rbx)
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 74 06 je 0x38
32: 0f 8e 5d 02 00 00 jle 0x295
38: 48 8d 7b 4b lea 0x4b(%rbx),%rdi
3c: 44 rex.R
3d: 0f .byte 0xf
3e: b6 6d mov $0x6d,%dh


Tested on:

commit: 8faabc04 Merge tag 'net-6.13-rc4' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f200c4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c22efbd20f8da769

dashboard link: https://syzkaller.appspot.com/bug?extid=bf6351831bc4f9148d98
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=170dcf30580000

[Tetsuo Handa]

#syz dup: general protection fault in account_kernel_stack (3)