Message-ID: <d6c0cfeb-f4bd-4564-84e4-a0db71608a6b@csgroup.eu>
Date: Mon, 2 Sep 2024 14:06:30 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Jinjie Ruan <ruanjinjie@...wei.com>, tglx@...utronix.de,
 linux-kernel@...r.kernel.org, "Peter Zijlstra (Intel)"
 <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>
Subject: Re: [PATCH] static_call: Fix a wild-memory-access bug in
 static_call_del_module()

Hi,

Le 02/09/2024 à 14:01, Jinjie Ruan a écrit :
> Hi, it seems that this bug still exit.

Can you provide more details ?

In particular, what makes you think it is the exact same bug ?

Christophe


> 
> On 2023/9/15 16:21, Jinjie Ruan wrote:
>> Inject fault while probing btrfs.ko, if the first kzalloc() fails
>> in __static_call_init(), key->mods will no be initialized. And then
>> in static_call_del_module() the site_mod->mod will cause
>> wild-memory-access as below:
>>
>> So assign key->mods to NULL in __static_call_init() if it fails
>> to fix the issue. And if kzalloc fails, it will just return in init
>> func, so it should break if it the key->mods is NULL in exit func.
>>
>>   general protection fault, probably for non-canonical address 0xeb800159c89f94a0: 0000 [#1] PREEMPT SMP KASAN
>>   KASAN: maybe wild-memory-access in range [0x5c002ace44fca500-0x5c002ace44fca507]
>>   CPU: 2 PID: 1843 Comm: modprobe Tainted: G        W        N 6.6.0-rc1+ #60
>>   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
>>   RIP: 0010:static_call_del_module+0x113/0x280
>>   Code: 3c 20 00 0f 85 ef 00 00 00 49 8b 6e 08 48 85 ed 75 0d eb 75 48 85 db 74 70 49 89 ef 48 89 dd 48 8d 7d 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 78 48 89 e8 4c 8b 6d 08 48 c1 e8 03 42 80 3c 20
>>   RSP: 0018:ffff888101d3f860 EFLAGS: 00010206
>>   RAX: 0b800559c89f94a0 RBX: 5c002ace44fca4f8 RCX: ffffffffa0210f00
>>   RDX: ffffffffa0210ed4 RSI: ffffffffa0210edc RDI: 5c002ace44fca500
>>   RBP: 5c002ace44fca4f8 R08: 0000000000000000 R09: ffffed10233e4eea
>>   R10: ffffed10233e4ee9 R11: ffff888119f2774b R12: dffffc0000000000
>>   R13: 80002ace3cfca4f8 R14: ffffffff85196de0 R15: ffffffff84ee9f99
>>   FS:  00007f4ff6faa540(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000
>>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>   CR2: 00007ffc3d1f19e8 CR3: 0000000109fa6001 CR4: 0000000000170ee0
>>   DR0: ffffffff8faefce8 DR1: ffffffff8faefce9 DR2: ffffffff8faefcea
>>   DR3: ffffffff8faefceb DR6: 00000000ffff0ff0 DR7: 0000000000000600
>>   Call Trace:
>>    <TASK>
>>    ? __die_body+0x1b/0x60
>>    ? die_addr+0x43/0x70
>>    ? exc_general_protection+0x121/0x210
>>    ? asm_exc_general_protection+0x22/0x30
>>    ? static_call_del_module+0x113/0x280
>>    ? __SCT__tp_func_ipi_exit+0x8/0x8
>>    static_call_module_notify+0x27f/0x390
>>    ? rcu_segcblist_inc_len+0x17/0x20
>>    notifier_call_chain+0xbf/0x280
>>    notifier_call_chain_robust+0x7f/0xe0
>>    ? notifier_call_chain+0x280/0x280
>>    ? kasan_quarantine_put+0x46/0x160
>>    blocking_notifier_call_chain_robust+0x5b/0x80
>>    load_module+0x4d1d/0x69f0
>>    ? module_frob_arch_sections+0x20/0x20
>>    ? update_cfs_group+0x10c/0x2a0
>>    ? __wake_up_common+0x10b/0x5d0
>>    ? kernel_read_file+0x3ca/0x510
>>    ? __x64_sys_fsconfig+0x650/0x650
>>    ? __schedule+0xa0b/0x2a60
>>    ? init_module_from_file+0xd2/0x130
>>    init_module_from_file+0xd2/0x130
>>    ? __ia32_sys_init_module+0xa0/0xa0
>>    ? _raw_spin_lock_irqsave+0xe0/0xe0
>>    ? ptrace_stop+0x487/0x790
>>    idempotent_init_module+0x32d/0x6a0
>>    ? init_module_from_file+0x130/0x130
>>    ? __fget_light+0x57/0x500
>>    __x64_sys_finit_module+0xbb/0x130
>>    do_syscall_64+0x35/0x80
>>    entry_SYSCALL_64_after_hwframe+0x46/0xb0
>>   RIP: 0033:0x7f4ff691b839
>>   Code: 00 f3 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 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48
>>   RSP: 002b:00007ffc07b09718 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
>>   RAX: ffffffffffffffda RBX: 000055978f13e070 RCX: 00007f4ff691b839
>>   RDX: 0000000000000000 RSI: 000055978da1bc2e RDI: 0000000000000003
>>   RBP: 000055978da1bc2e R08: 0000000000000000 R09: 000055978f13ddb0
>>   R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
>>   R13: 000055978f13e020 R14: 0000000000040000 R15: 000055978f13ddb0
>>    </TASK>
>>   Modules linked in: tifm_core(+)
>>   Dumping ftrace buffer:
>>      (ftrace buffer empty)
>>   ---[ end trace 0000000000000000 ]---
>>   RIP: 0010:static_call_del_module+0x113/0x280
>>   Code: 3c 20 00 0f 85 ef 00 00 00 49 8b 6e 08 48 85 ed 75 0d eb 75 48 85 db 74 70 49 89 ef 48 89 dd 48 8d 7d 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 78 48 89 e8 4c 8b 6d 08 48 c1 e8 03 42 80 3c 20
>>   RSP: 0018:ffff888101d3f860 EFLAGS: 00010206
>>   RAX: 0b800559c89f94a0 RBX: 5c002ace44fca4f8 RCX: ffffffffa0210f00
>>   RDX: ffffffffa0210ed4 RSI: ffffffffa0210edc RDI: 5c002ace44fca500
>>   RBP: 5c002ace44fca4f8 R08: 0000000000000000 R09: ffffed10233e4eea
>>   R10: ffffed10233e4ee9 R11: ffff888119f2774b R12: dffffc0000000000
>>   R13: 80002ace3cfca4f8 R14: ffffffff85196de0 R15: ffffffff84ee9f99
>>   FS:  00007f4ff6faa540(0000) GS:ffff888119f00000(0000) knlGS:0000000000000000
>>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>   CR2: 00007ffc3d1f19e8 CR3: 0000000109fa6001 CR4: 0000000000170ee0
>>   DR0: ffffffff8faefce8 DR1: ffffffff8faefce9 DR2: ffffffff8faefcea
>>   DR3: ffffffff8faefceb DR6: 00000000ffff0ff0 DR7: 0000000000000600
>>   Kernel panic - not syncing: Fatal exception
>>   Dumping ftrace buffer:
>>      (ftrace buffer empty)
>>   Kernel Offset: disabled
>>   Rebooting in 1 seconds..
>>
>> Fixes: 8fd4ddda2f49 ("static_call: Don't make __static_call_return0 static")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
>> ---
>>   kernel/static_call_inline.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
>> index 639397b5491c..e7aa70d33530 100644
>> --- a/kernel/static_call_inline.c
>> +++ b/kernel/static_call_inline.c
>> @@ -256,8 +256,10 @@ static int __static_call_init(struct module *mod,
>>   			}
>>   
>>   			site_mod = kzalloc(sizeof(*site_mod), GFP_KERNEL);
>> -			if (!site_mod)
>> +			if (!site_mod) {
>> +				key->mods = NULL;
>>   				return -ENOMEM;
>> +			}
>>   
>>   			/*
>>   			 * When the key has a direct sites pointer, extract
>> @@ -422,7 +424,7 @@ static void static_call_del_module(struct module *mod)
>>   			;
>>   
>>   		if (!site_mod)
>> -			continue;
>> +			break;
>>   
>>   		*prev = site_mod->next;
>>   		kfree(site_mod);

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