linux-kernel - [PATCH] x86/mpx: pass 'mm' to kernel_managing_mpx_tables() in mpx_notify

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Date:   Mon,  3 Dec 2018 12:43:57 -0800
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, luto@...nel.org,
        peterz@...radead.org,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>
Subject: [PATCH] x86/mpx: pass 'mm' to kernel_managing_mpx_tables() in mpx_notify_unmap()

If mm is not the same as current->mm, mpx_notify_unmap() will yield
invalid results and at worst will lead to a crash if it gets called by
a kthread.

Cc: Dave Hansen <dave.hansen@...el.com>
Fixes: 1de4fa14ee25 ("x86, mpx: Cleanup unused bound tables")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
 arch/x86/mm/mpx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 2385538e8065..15fb62657ee9 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -882,7 +882,7 @@ static int mpx_unmap_tables(struct mm_struct *mm,
  * necessary, and the 'vma' is the first vma in this range (start -> end).
  */
 void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
-		unsigned long start, unsigned long end)
+		      unsigned long start, unsigned long end)
 {
 	int ret;
 
@@ -890,7 +890,7 @@ void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * Refuse to do anything unless userspace has asked
 	 * the kernel to help manage the bounds tables,
 	 */
-	if (!kernel_managing_mpx_tables(current->mm))
+	if (!kernel_managing_mpx_tables(mm))
 		return;
 	/*
 	 * This will look across the entire 'start -> end' range,
-- 
2.19.1