From: Dave Hansen <dave.hansen@intel.com>
To: Qiaowei Ren <qiaowei.ren@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>
Cc: x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@linux-mips.org
Subject: Re: [PATCH v9 09/12] x86, mpx: decode MPX instruction to get bound violation information
Date: Thu, 30 Oct 2014 15:38:16 -0700 [thread overview]
Message-ID: <5452BDD8.2080605@intel.com> (raw)
In-Reply-To: <1413088915-13428-10-git-send-email-qiaowei.ren@intel.com>
> +void do_mpx_bounds(struct pt_regs *regs, siginfo_t *info,
> + struct xsave_struct *xsave_buf)
> +{
> + struct mpx_insn insn;
> + uint8_t bndregno;
> + unsigned long addr_vio;
> +
> + addr_vio = mpx_insn_decode(&insn, regs);
> +
> + bndregno = X86_MODRM_REG(insn.modrm.value);
> + if (bndregno > 3)
> + return;
> +
> + /* Note: the upper 32 bits are ignored in 32-bit mode. */
> + info->si_lower = (void __user *)(unsigned long)
> + (xsave_buf->bndregs.bndregs[2*bndregno]);
> + info->si_upper = (void __user *)(unsigned long)
> + (~xsave_buf->bndregs.bndregs[2*bndregno+1]);
> + info->si_addr_lsb = 0;
> + info->si_signo = SIGSEGV;
> + info->si_errno = 0;
> + info->si_code = SEGV_BNDERR;
> + info->si_addr = (void __user *)addr_vio;
> +}
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 611b6ec..b2a916b 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -284,6 +284,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
> unsigned long status;
> struct xsave_struct *xsave_buf;
> struct task_struct *tsk = current;
> + siginfo_t info;
>
> prev_state = exception_enter();
> if (notify_die(DIE_TRAP, "bounds", regs, error_code,
> @@ -316,6 +317,11 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
> break;
>
> case 1: /* Bound violation. */
> + do_mpx_bounds(regs, &info, xsave_buf);
> + do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs,
> + error_code, &info);
> + break;
> +
> case 0: /* No exception caused by Intel MPX operations. */
> do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, NULL);
> break;
>
So, siginfo is stack-allocarted here. do_mpx_bounds() can error out if
it sees an invalid bndregno. We still send the signal with the &info
whether or not we filled the 'info' in do_mpx_bounds().
Can't this leak some kernel stack out in the 'info'?
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next prev parent reply other threads:[~2014-10-30 22:38 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-12 4:41 [PATCH v9 00/12] Intel MPX support Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 01/12] x86, mpx: introduce VM_MPX to indicate that a VMA is MPX specific Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 02/12] x86, mpx: rename cfg_reg_u and status_reg Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 03/12] x86, mpx: add MPX specific mmap interface Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 04/12] x86, mpx: add MPX to disaabled features Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 05/12] x86, mpx: on-demand kernel allocation of bounds tables Qiaowei Ren
2014-10-24 12:08 ` Thomas Gleixner
2014-10-27 3:20 ` Ren Qiaowei
2014-10-28 17:43 ` Dave Hansen
2014-10-28 17:57 ` Thomas Gleixner
2014-10-12 4:41 ` [PATCH v9 06/12] mpx: extend siginfo structure to include bound violation information Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 07/12] mips: sync struct siginfo with general version Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 08/12] ia64: " Qiaowei Ren
2014-10-12 4:41 ` [PATCH v9 09/12] x86, mpx: decode MPX instruction to get bound violation information Qiaowei Ren
2014-10-24 12:36 ` Thomas Gleixner
2014-10-27 1:43 ` Ren, Qiaowei
2014-10-27 20:36 ` Thomas Gleixner
2014-10-28 5:58 ` Ren Qiaowei
2014-10-31 20:16 ` Dave Hansen
2014-10-31 20:33 ` Thomas Gleixner
2014-10-30 22:38 ` Dave Hansen [this message]
2014-10-31 2:12 ` Ren Qiaowei
2014-10-31 9:09 ` Thomas Gleixner
2014-10-12 4:41 ` [PATCH v9 10/12] x86, mpx: add prctl commands PR_MPX_ENABLE_MANAGEMENT, PR_MPX_DISABLE_MANAGEMENT Qiaowei Ren
2014-10-24 12:49 ` Thomas Gleixner
2014-10-24 15:10 ` Thomas Gleixner
2014-10-27 2:17 ` Ren, Qiaowei
2014-10-27 20:38 ` Thomas Gleixner
2014-10-28 5:57 ` Ren Qiaowei
2014-10-12 4:41 ` [PATCH v9 11/12] x86, mpx: cleanup unused bound tables Qiaowei Ren
2014-10-24 14:40 ` Thomas Gleixner
2014-10-27 3:13 ` Ren Qiaowei
2014-10-27 20:49 ` Thomas Gleixner
2014-10-28 5:56 ` Ren Qiaowei
2014-10-28 10:42 ` Thomas Gleixner
2014-11-03 20:53 ` Dave Hansen
2014-11-03 21:29 ` Thomas Gleixner
2014-11-04 16:00 ` Dave Hansen
2014-11-04 17:02 ` Thomas Gleixner
2014-11-06 21:50 ` Dave Hansen
2014-11-11 18:27 ` Thomas Gleixner
2014-11-11 20:44 ` Dave Hansen
2014-11-11 21:36 ` Thomas Gleixner
2014-10-12 4:41 ` [PATCH v9 12/12] x86, mpx: add documentation on Intel MPX Qiaowei Ren
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