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@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Link: http://lkml.kernel.org/r/20120729182229.GA20329@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 5db150b..bed2161 100644 (file)
--- 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) {