linux-kernel - Re: [PATCH-next] x86/kernel: Fix unchecked return value

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Message-ID: <20210516131714.GB32445@ard0534>
Date:   Sun, 16 May 2021 14:17:14 +0100
From:   Khaled Romdhani <khaledromdhani216@...il.com>
To:     Colin Ian King <colin.king@...onical.com>,
        Borislav Petkov <bp@...en8.de>
Cc:     peterz@...radead.org, jpoimboe@...hat.com, jbaron@...mai.com,
        rostedt@...dmis.org, ardb@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, x86@...nel.org, hpa@...or.com,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH-next] x86/kernel: Fix unchecked return value

On Sat, May 15, 2021 at 09:51:23PM +0100, Colin Ian King wrote:
> 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@...il.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

Yes. I shall be.

Thanks,

Khaled.