linux-kernel - Re: [PATCH][v2] uprobes/x86: emulate push insns for uprobe on x86

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

Message-ID: <20171114153424.GA17667@redhat.com>
Date:   Tue, 14 Nov 2017 16:34:24 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Yonghong Song <yhs@...com>
Cc:     mingo@...nel.org, tglx@...utronix.de, peterz@...radead.org,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        netdev@...r.kernel.org, ast@...com, kernel-team@...com
Subject: Re: [PATCH][v2] uprobes/x86: emulate push insns for uprobe on x86

On 11/13, Yonghong Song wrote:
>
> On 11/13/17 4:59 AM, Oleg Nesterov wrote:
> >>+		switch (opc1) {
> >>+		case 0x50:
> >>+			reg_offset = offsetof(struct pt_regs, r8);
> >>+			break;
> >>+		case 0x51:
> >>+			reg_offset = offsetof(struct pt_regs, r9);
> >>+			break;
> >>+		case 0x52:
> >>+			reg_offset = offsetof(struct pt_regs, r10);
> >>+			break;
> >>+		case 0x53:
> >>+			reg_offset = offsetof(struct pt_regs, r11);
> >>+			break;
> >>+		case 0x54:
> >>+			reg_offset = offsetof(struct pt_regs, r12);
> >>+			break;
> >>+		case 0x55:
> >>+			reg_offset = offsetof(struct pt_regs, r13);
> >>+			break;
> >>+		case 0x56:
> >>+			reg_offset = offsetof(struct pt_regs, r14);
> >>+			break;
> >>+		case 0x57:
> >>+			reg_offset = offsetof(struct pt_regs, r15);
> >>+			break;
> >>+		}
> >>+#else
> >>+		return -ENOSYS;
> >>+#endif
> >
> >OK, but shouldn't we also return ENOSYS if CONFIG_X86_64=y but the probed task is 32bit?
>
> Just tested with a 32bit app on x86 box and segfaults.

Hmm. How did you verify this?

Your v3 doesn't look right and it seems you misunderstood me...

> Yes, we would need to
> return ENOSYS if the app is 32bit on 64bit system.

Only if insn->length == 2. "push bp" and other valid 32bit push'es should be
emulated correctly or your patch is wrong. Confused...

> >Or in this case uprobe_init_insn(x86_64 => false) should fail and push_setup_xol_ops()
> >won't be called?

So it doesn't fail?

Oleg.