From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>,
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: Mon, 10 Oct 2022 17:08:14 +0100 [thread overview]
Message-ID: <Y0RDblEkJ0h+DfCB@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAMj1kXHn70rRaB=BgCrMoqQxRcq=HzZ0NWFYL+FqV_037PaY3w@mail.gmail.com>
On Mon, Oct 10, 2022 at 01:06:19PM +0200, 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.
Why? We won't get here unless the PC can be dereferenced. If it's not
able to be dereferenced, then we'd be dealing with a prefetch abort.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2022-10-10 16:08 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) [this message]
2022-10-10 16:14 ` Ard Biesheuvel
2022-10-10 16:17 ` Russell King (Oracle)
2022-10-11 2:29 ` Leizhen (ThunderTown)
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)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Y0RDblEkJ0h+DfCB@shell.armlinux.org.uk \
--to=linux@armlinux.org.uk \
--cc=ardb@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=thunder.leizhen@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).