linux-kernel - [tip:perf/core] uprobes: No need to re-check vma_address() in write

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Date:	Mon, 18 Jun 2012 01:57:57 -0700
From:	tip-bot for Oleg Nesterov <oleg@...hat.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, ananth@...ibm.com, anton@...hat.com,
	srikar@...ux.vnet.ibm.com, tglx@...utronix.de, oleg@...hat.com
Subject: [tip:perf/core] uprobes: No need to re-check vma_address()
  in write_opcode()

Commit-ID:  eb2bf57bee42c7565032f93adaa211e2c9fcc52c
Gitweb:     http://git.kernel.org/tip/eb2bf57bee42c7565032f93adaa211e2c9fcc52c
Author:     Oleg Nesterov <oleg@...hat.com>
AuthorDate: Fri, 15 Jun 2012 17:43:47 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 16 Jun 2012 09:10:47 +0200

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>
Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Anton Arapov <anton@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/20120615154347.GA9604@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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 2db1d94..14c71a2 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)
--
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