linux-kernel - [PATCH 1/5] uprobes: uprobe_mmap/munmap needs list_for_each_entry

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Date:	Sun, 8 Jul 2012 22:30:01 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] uprobes: uprobe_mmap/munmap needs
	list_for_each_entry_safe()

The bug was introduced by me in 449d0d7c "uprobes: Simplify the
usage of uprobe->pending_list".

Yes, we do not care about uprobe->pending_list after return and
nobody can remove the current list entry, but put_uprobe(uprobe)
can actually free it and thus we need list_for_each_safe().

Reported-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 67697db..a93b6df 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1010,7 +1010,7 @@ static void build_probe_list(struct inode *inode, struct list_head *head)
 int uprobe_mmap(struct vm_area_struct *vma)
 {
 	struct list_head tmp_list;
-	struct uprobe *uprobe;
+	struct uprobe *uprobe, *u;
 	struct inode *inode;
 	int ret, count;
 
@@ -1028,7 +1028,7 @@ int uprobe_mmap(struct vm_area_struct *vma)
 	ret = 0;
 	count = 0;
 
-	list_for_each_entry(uprobe, &tmp_list, pending_list) {
+	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
 		if (!ret) {
 			loff_t vaddr = vma_address(vma, uprobe->offset);
 
@@ -1076,7 +1076,7 @@ int uprobe_mmap(struct vm_area_struct *vma)
 void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
 {
 	struct list_head tmp_list;
-	struct uprobe *uprobe;
+	struct uprobe *uprobe, *u;
 	struct inode *inode;
 
 	if (!atomic_read(&uprobe_events) || !valid_vma(vma, false))
@@ -1093,7 +1093,7 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 	mutex_lock(uprobes_mmap_hash(inode));
 	build_probe_list(inode, &tmp_list);
 
-	list_for_each_entry(uprobe, &tmp_list, pending_list) {
+	list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
 		loff_t vaddr = vma_address(vma, uprobe->offset);
 
 		if (vaddr >= start && vaddr < end) {
-- 
1.5.5.1

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