From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] ARM: Fix some check warnings of tool sparse
Date: Tue, 11 Oct 2022 10:29:58 +0800 [thread overview]
Message-ID: <c262c991-ad1e-81e6-4909-b8c4a1c036ff@huawei.com> (raw)
In-Reply-To: <CAMj1kXHn70rRaB=BgCrMoqQxRcq=HzZ0NWFYL+FqV_037PaY3w@mail.gmail.com>
On 2022/10/10 19:06, Ard Biesheuvel wrote:
> On Mon, 10 Oct 2022 at 12:58, Leizhen (ThunderTown)
> <thunder.leizhen@huawei.com> wrote:
>>
>>
>>
>> On 2022/10/10 18:20, Ard Biesheuvel wrote:
>>> On Mon, 10 Oct 2022 at 11:56, Zhen Lei <thunder.leizhen@huawei.com> wrote:
>>>>
>>>> Fix the following warnings:
>>>> warning: incorrect type in initializer (different address spaces)
>>>> expected unsigned short [noderef] __user *register __p
>>>> got unsigned short [usertype] *
>>>> warning: cast removes address space '__user' of expression
>>>>
>>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>>>> ---
>>>> arch/arm/kernel/traps.c | 10 +++++-----
>>>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
>>>> index 20b2db6dcd1ced7..34aa80c09c508c1 100644
>>>> --- a/arch/arm/kernel/traps.c
>>>> +++ b/arch/arm/kernel/traps.c
>>>> @@ -188,9 +188,9 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
>>>> }
>>>> } else {
>>>> if (thumb)
>>>> - bad = get_user(val, &((u16 *)addr)[i]);
>>>> + bad = get_user(val, &((u16 __user *)addr)[i]);
>>>> else
>>>> - bad = get_user(val, &((u32 *)addr)[i]);
>>>> + bad = get_user(val, &((u32 __user *)addr)[i]);
>>>> }
>>>>
>>>> if (!bad)
>>>> @@ -455,15 +455,15 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
>>>> if (processor_mode(regs) == SVC_MODE) {
>>>> #ifdef CONFIG_THUMB2_KERNEL
>>>> if (thumb_mode(regs)) {
>>>> - instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>>>> + instr = __mem_to_opcode_thumb16(((__force u16 *)pc)[0]);
>>>
>>> Shouldn't this be __user as well? (and below)
>>
>> unsigned int instr;
>> void __user *pc;
>>
>> The __user can clear the warning, but a new warning will be generated.
>>
>> instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
>> ^new ^old
>>
>> arch/arm/kernel/traps.c:473:33: warning: dereference of noderef expression
>>
>
> This is because dereferencing a __user pointer is not permitted.
>
> So this code should be using get_kernel_nofault() here not a plain
> dereference of PC. So better to fix that properly instead of papering
> over it with a __force cast just to make sparse happy.
How about:
@@ -451,9 +451,9 @@ int call_undef_hook(struct pt_regs *regs, unsigned int instr)
asmlinkage void do_undefinstr(struct pt_regs *regs)
{
unsigned int instr;
- void __user *pc;
+ void *pc;
- pc = (void __user *)instruction_pointer(regs);
+ pc = (void *)instruction_pointer(regs);
if (processor_mode(regs) == SVC_MODE) {
#ifdef CONFIG_THUMB2_KERNEL
@@ -497,7 +497,7 @@ asmlinkage void do_undefinstr(struct pt_regs *regs)
}
#endif
arm_notify_die("Oops - undefined instruction", regs,
- SIGILL, ILL_ILLOPC, pc, 0, 6);
+ SIGILL, ILL_ILLOPC, (void __user *)pc, 0, 6);
}
NOKPROBE_SYMBOL(do_undefinstr)
The 'pc' may come from kernel or user. And I found that all the get_user()
calls have already done type casts to the pc, except arm_notify_die().
I think the above changes are reasonable.
>
>
>>>
>>>> if (is_wide_instruction(instr)) {
>>>> u16 inst2;
>>>> - inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
>>>> + inst2 = __mem_to_opcode_thumb16(((__force u16 *)pc)[1]);
>>>> instr = __opcode_thumb32_compose(instr, inst2);
>>>> }
>>>> } else
>>>> #endif
>>>> - instr = __mem_to_opcode_arm(*(u32 *) pc);
>>>> + instr = __mem_to_opcode_arm(*(__force u32 *) pc);
>>>> } else if (thumb_mode(regs)) {
>>>> if (get_user(instr, (u16 __user *)pc))
>>>> goto die_sig;
>>>> --
>>>> 2.25.1
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-arm-kernel mailing list
>>>> linux-arm-kernel@lists.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>> .
>>>
>>
>> --
>> Regards,
>> Zhen Lei
> .
>
--
Regards,
Zhen Lei
next prev parent reply other threads:[~2022-10-11 2:30 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-10 9:53 [PATCH v2 0/2] ARM: Make the dumped instructions are consistent with the disassembled ones Zhen Lei
2022-10-10 9:53 ` [PATCH v2 1/2] ARM: Fix some check warnings of tool sparse Zhen Lei
2022-10-10 10:20 ` Ard Biesheuvel
2022-10-10 10:58 ` Leizhen (ThunderTown)
2022-10-10 11:06 ` Ard Biesheuvel
2022-10-10 16:08 ` Russell King (Oracle)
2022-10-10 16:14 ` Ard Biesheuvel
2022-10-10 16:17 ` Russell King (Oracle)
2022-10-11 2:29 ` Leizhen (ThunderTown) [this message]
2022-10-13 10:51 ` Russell King (Oracle)
2022-10-13 11:34 ` Leizhen (ThunderTown)
2022-11-28 8:39 ` Leizhen (ThunderTown)
2022-10-10 16:05 ` Russell King (Oracle)
2022-10-11 2:13 ` Leizhen (ThunderTown)
2022-10-13 1:28 ` Leizhen (ThunderTown)
2022-10-10 9:53 ` [PATCH v2 2/2] ARM: Make the dumped instructions are consistent with the disassembled ones Zhen Lei
2022-10-10 10:10 ` Ard Biesheuvel
2022-10-10 10:46 ` Leizhen (ThunderTown)
2022-10-10 11:07 ` Ard Biesheuvel
2022-10-10 11:29 ` Leizhen (ThunderTown)
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