From: Ren Qiaowei <qiaowei.ren@intel.com>
To: Dave Hansen <dave.hansen@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: Fri, 31 Oct 2014 10:12:07 +0800 [thread overview]
Message-ID: <5452EFF7.4090204@intel.com> (raw)
In-Reply-To: <5452BDD8.2080605@intel.com>
On 10/31/2014 06:38 AM, Dave Hansen wrote:
>> +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'?
>
This should check the return value of do_mpx_bounds and should be fixed.
Thanks,
Qiaowei
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next prev parent reply other threads:[~2014-10-31 2:15 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
2014-10-31 2:12 ` Ren Qiaowei [this message]
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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