From: Peilin Ye <yepeilin.cs@gmail.com>
To: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org,
Elvira Khabirova <lineprinter@altlinux.org>,
linux-kernel-mentees@lists.linuxfoundation.org,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [Linux-kernel-mentees] [PATCH] ptrace: Prevent kernel-infoleak in ptrace_get_syscall_info()
Date: Fri, 31 Jul 2020 21:28:04 -0400 [thread overview]
Message-ID: <20200801012804.GA220239@PWN> (raw)
In-Reply-To: <20200801002142.GA27762@altlinux.org>
On Sat, Aug 01, 2020 at 03:21:42AM +0300, Dmitry V. Levin wrote:
> On Mon, Jul 27, 2020 at 05:36:44PM -0400, Peilin Ye wrote:
> > ptrace_get_syscall_info() is copying uninitialized stack memory to
> > userspace due to the compiler not initializing holes in statically
> > allocated structures. Fix it by initializing `info` with memset().
> >
> > Cc: stable@vger.kernel.org
> > Fixes: 201766a20e30 ("ptrace: add PTRACE_GET_SYSCALL_INFO request")
> > Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
> > ---
> > kernel/ptrace.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> > index 43d6179508d6..e48d05b765b5 100644
> > --- a/kernel/ptrace.c
> > +++ b/kernel/ptrace.c
> > @@ -960,15 +960,17 @@ ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
> > void __user *datavp)
> > {
> > struct pt_regs *regs = task_pt_regs(child);
> > - struct ptrace_syscall_info info = {
> > - .op = PTRACE_SYSCALL_INFO_NONE,
> > - .arch = syscall_get_arch(child),
> > - .instruction_pointer = instruction_pointer(regs),
> > - .stack_pointer = user_stack_pointer(regs),
> > - };
> > + struct ptrace_syscall_info info;
> > unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
> > unsigned long write_size;
> >
> > + memset(&info, 0, sizeof(info));
> > +
> > + info.op = PTRACE_SYSCALL_INFO_NONE;
> > + info.arch = syscall_get_arch(child);
> > + info.instruction_pointer = instruction_pointer(regs);
> > + info.stack_pointer = user_stack_pointer(regs);
> > +
>
> No, please don't do it this way. If there is a hole in the structure that
> the compiler is unable to initialize properly (and there is a 3-byte hole
> in the beginning indeed), please plug the hole by turning it into
> something that the compiler is capable of initializing.
I see. I will do that and send a v2.
> Also, please do not forget to Cc authors of the commit you are fixing.
Sorry, I forgot about that. Thank you for pointing it out!
Peilin Ye
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WARNING: multiple messages have this Message-ID (diff)
From: Peilin Ye <yepeilin.cs@gmail.com>
To: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: Elvira Khabirova <lineprinter@altlinux.org>,
Oleg Nesterov <oleg@redhat.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel-mentees@lists.linuxfoundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH] ptrace: Prevent kernel-infoleak in ptrace_get_syscall_info()
Date: Fri, 31 Jul 2020 21:28:04 -0400 [thread overview]
Message-ID: <20200801012804.GA220239@PWN> (raw)
In-Reply-To: <20200801002142.GA27762@altlinux.org>
On Sat, Aug 01, 2020 at 03:21:42AM +0300, Dmitry V. Levin wrote:
> On Mon, Jul 27, 2020 at 05:36:44PM -0400, Peilin Ye wrote:
> > ptrace_get_syscall_info() is copying uninitialized stack memory to
> > userspace due to the compiler not initializing holes in statically
> > allocated structures. Fix it by initializing `info` with memset().
> >
> > Cc: stable@vger.kernel.org
> > Fixes: 201766a20e30 ("ptrace: add PTRACE_GET_SYSCALL_INFO request")
> > Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
> > ---
> > kernel/ptrace.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> > index 43d6179508d6..e48d05b765b5 100644
> > --- a/kernel/ptrace.c
> > +++ b/kernel/ptrace.c
> > @@ -960,15 +960,17 @@ ptrace_get_syscall_info(struct task_struct *child, unsigned long user_size,
> > void __user *datavp)
> > {
> > struct pt_regs *regs = task_pt_regs(child);
> > - struct ptrace_syscall_info info = {
> > - .op = PTRACE_SYSCALL_INFO_NONE,
> > - .arch = syscall_get_arch(child),
> > - .instruction_pointer = instruction_pointer(regs),
> > - .stack_pointer = user_stack_pointer(regs),
> > - };
> > + struct ptrace_syscall_info info;
> > unsigned long actual_size = offsetof(struct ptrace_syscall_info, entry);
> > unsigned long write_size;
> >
> > + memset(&info, 0, sizeof(info));
> > +
> > + info.op = PTRACE_SYSCALL_INFO_NONE;
> > + info.arch = syscall_get_arch(child);
> > + info.instruction_pointer = instruction_pointer(regs);
> > + info.stack_pointer = user_stack_pointer(regs);
> > +
>
> No, please don't do it this way. If there is a hole in the structure that
> the compiler is unable to initialize properly (and there is a 3-byte hole
> in the beginning indeed), please plug the hole by turning it into
> something that the compiler is capable of initializing.
I see. I will do that and send a v2.
> Also, please do not forget to Cc authors of the commit you are fixing.
Sorry, I forgot about that. Thank you for pointing it out!
Peilin Ye
next prev parent reply other threads:[~2020-08-01 1:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 21:36 [Linux-kernel-mentees] [PATCH] ptrace: Prevent kernel-infoleak in ptrace_get_syscall_info() Peilin Ye
2020-07-27 21:36 ` Peilin Ye
2020-08-01 0:21 ` Dmitry V. Levin
2020-08-01 0:21 ` Dmitry V. Levin
2020-08-01 1:28 ` Peilin Ye [this message]
2020-08-01 1:28 ` Peilin Ye
2020-08-01 2:08 ` [Linux-kernel-mentees] [PATCH v2] " Peilin Ye
2020-08-01 2:08 ` Peilin Ye
2020-08-01 11:06 ` Dmitry V. Levin
2020-08-01 11:06 ` Dmitry V. Levin
2020-08-01 15:09 ` Peilin Ye
2020-08-01 15:09 ` Peilin Ye
2020-08-01 15:20 ` [Linux-kernel-mentees] [PATCH v3] " Peilin Ye
2020-08-01 15:20 ` Peilin Ye
2020-08-01 16:08 ` Dmitry V. Levin
2020-08-01 16:08 ` Dmitry V. Levin
2020-08-01 20:10 ` Christian Brauner
2020-08-01 20:10 ` Christian Brauner
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