From: Kees Cook <keescook@chromium.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>, Joerg Roedel <jroedel@suse.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
"Gustavo A . R . Silva" <gustavoars@kernel.org>,
Jann Horn <jannh@google.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] x86/uprobes: Fix not using prefixes.nbytes for loop over prefixes.bytes
Date: Wed, 2 Dec 2020 11:04:41 -0800 [thread overview]
Message-ID: <202012021103.5A8030BF7A@keescook> (raw)
In-Reply-To: <160689907597.3084105.18019089399087866918.stgit@devnote2>
On Wed, Dec 02, 2020 at 05:51:16PM +0900, Masami Hiramatsu wrote:
> 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@vger.kernel.org
> Reported-by: Kees Cook <keescook@chromium.org>
This should probably be:
Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com
Debugged-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> 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;
> }
>
--
Kees Cook
next prev parent reply other threads:[~2020-12-02 19:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-02 8:50 [PATCH 0/3] x86/insn: Fix not using prefixes.nbytes for loop over prefixes.bytes Masami Hiramatsu
2020-12-02 8:51 ` [PATCH 1/3] x86/sev-es: " Masami Hiramatsu
2020-12-02 15:31 ` Tom Lendacky
2020-12-02 19:07 ` Kees Cook
2020-12-03 2:03 ` Masami Hiramatsu
2020-12-02 8:51 ` [PATCH 2/3] x86/uprobes: " Masami Hiramatsu
2020-12-02 14:51 ` Srikar Dronamraju
2020-12-03 4:20 ` Masami Hiramatsu
2020-12-02 19:04 ` Kees Cook [this message]
2020-12-03 2:00 ` Masami Hiramatsu
2020-12-02 8:51 ` [PATCH 3/3] x86/insn-eval: " Masami Hiramatsu
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