linux-kernel - [PATCH 3/6] uprobes: no need to re-check vma_address() in write

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Message-ID: <20120613185030.GC13878@redhat.com>
Date:	Wed, 13 Jun 2012 20:50:30 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] uprobes: no need to re-check vma_address() in
	write_opcode()

write_opcode() is called by register_for_each_vma() and uprobe_mmap()
paths. In both cases the caller has already verified this vaddr under
mmap_sem, no need to re-check.

Note also that this check is wrong anyway, we should not truncate
loff_t returned by vma_address() if we do not trust this mapping.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 9bb5571..799d6ed 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -211,7 +211,6 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 	struct vm_area_struct *vma;
 	struct uprobe *uprobe;
 	unsigned long pgoff;
-	loff_t addr;
 	int ret;
 retry:
 	/* Read the page with vaddr into memory */
@@ -235,10 +234,6 @@ retry:
 	if (mapping != vma->vm_file->f_mapping)
 		goto put_out;
 
-	addr = vma_address(vma, uprobe->offset);
-	if (vaddr != (unsigned long)addr)
-		goto put_out;
-
 	ret = -ENOMEM;
 	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 	if (!new_page)
-- 
1.5.5.1


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