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Subject: Re: [PATCH-next] x86/kernel: Fix unchecked return value
To:     Borislav Petkov <bp@alien8.de>,
        Khaled ROMDHANI <khaledromdhani216@gmail.com>
Cc:     peterz@infradead.org, jpoimboe@redhat.com, jbaron@akamai.com,
        rostedt@goodmis.org, ardb@kernel.org, tglx@linutronix.de,
        mingo@redhat.com, x86@kernel.org, hpa@zytor.com,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
References: <20210515202212.24836-1-khaledromdhani216@gmail.com>
 <YKAw3Yl8c6nU1zng@zn.tnic>
From:   Colin Ian King <colin.king@canonical.com>
Message-ID: <6f149c2e-eeb0-6b50-2b54-a56ae4646ea5@canonical.com>
Date:   Sat, 15 May 2021 21:51:23 +0100
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On 15/05/2021 21:36, Borislav Petkov wrote:
> On Sat, May 15, 2021 at 09:22:12PM +0100, Khaled ROMDHANI wrote:
>> From the coverity scan analysis, the return value from
>> insn_decode_kernel is not checked. It is a macro constructed
>> from the insn_decode function which may fail and return
>> negative integer. Fix this by explicitly checking the
>> return value.
>>
>> Addresses-Coverity: ("Unchecked return value")
>> Signed-off-by: Khaled ROMDHANI <khaledromdhani216@gmail.com>
>> ---
>>  arch/x86/kernel/jump_label.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
>> index a762dc1c615e..bf0ea003b6e7 100644
>> --- a/arch/x86/kernel/jump_label.c
>> +++ b/arch/x86/kernel/jump_label.c
>> @@ -23,7 +23,7 @@ int arch_jump_entry_size(struct jump_entry *entry)
>>  {
>>  	struct insn insn = {};
>>  
>> -	insn_decode_kernel(&insn, (void *)jump_entry_code(entry));
>> +	WARN_ON(insn_decode_kernel(&insn, (void *)jump_entry_code(entry)));
> 
> I don't think coverity is smart enough to notice...
> 
>>  	BUG_ON(insn.length != 2 && insn.length != 5);
> 	^^^^^^^^^^^^^
> 
> ... this line.
> 
> 
Indeed. One needs to be careful with false positives with Coverity.

Colin