linux-kernel - Re: [PATCH 2/3] x86/uprobes: Fix not using prefixes.nbytes for loop over prefixes.bytes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20201203132032.392d7dce940ed89c34341169@kernel.org>
Date:   Thu, 3 Dec 2020 13:20:32 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Kees Cook <keescook@...omium.org>,
        "H . Peter Anvin" <hpa@...or.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "Gustavo A . R . Silva" <gustavoars@...nel.org>,
        Jann Horn <jannh@...gle.com>,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] x86/uprobes: Fix not using prefixes.nbytes for loop
 over prefixes.bytes

On Wed, 2 Dec 2020 20:21:35 +0530
Srikar Dronamraju <srikar@...ux.vnet.ibm.com> wrote:

> * Masami Hiramatsu <mhiramat@...nel.org> [2020-12-02 17:51:16]:
> 
> > Since the insn.prefixes.nbytes can be bigger than the size of
> > insn.prefixes.bytes[] when a same prefix is repeated, we have to
> > check whether the insn.prefixes.bytes[i] != 0 and i < 4 instead
> > of insn.prefixes.nbytes.
> > 
> > Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints")
> > Cc: stable@...r.kernel.org
> > Reported-by: Kees Cook <keescook@...omium.org>
> > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> 
> Looks good to me.
> 
> Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

Thanks Srikar!


> 
> > ---
> >  arch/x86/kernel/uprobes.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
> > index 3fdaa042823d..bb3ea3705b99 100644
> > --- a/arch/x86/kernel/uprobes.c
> > +++ b/arch/x86/kernel/uprobes.c
> > @@ -257,7 +257,7 @@ static bool is_prefix_bad(struct insn *insn)
> >  {
> >  	int i;
> > 
> > -	for (i = 0; i < insn->prefixes.nbytes; i++) {
> > +	for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) {
> >  		insn_attr_t attr;
> > 
> >  		attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]);
> > @@ -746,7 +746,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
> >  	 * Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
> >  	 * No one uses these insns, reject any branch insns with such prefix.
> >  	 */
> > -	for (i = 0; i < insn->prefixes.nbytes; i++) {
> > +	for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) {
> >  		if (insn->prefixes.bytes[i] == 0x66)
> >  			return -ENOTSUPP;
> >  	}
> > 
> 
> -- 
> Thanks and Regards
> Srikar Dronamraju


-- 
Masami Hiramatsu <mhiramat@...nel.org>