lkml.org 
[lkml]   [2014]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 3.2 052/102] be careful with nd->inode in path_init() and follow_dotdot_rcu()
3.2.64-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@zeniv.linux.org.uk>

commit 4023bfc9f351a7994fb6a7d515476c320f94a574 upstream.

in the former we simply check if dentry is still valid after picking
its ->d_inode; in the latter we fetch ->d_inode in the same places
where we fetch dentry and its ->d_seq, under the same checks.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/namei.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -913,6 +913,7 @@ static bool __follow_mount_rcu(struct na

static int follow_dotdot_rcu(struct nameidata *nd)
{
+ struct inode *inode = nd->inode;
if (!nd->root.mnt)
set_root_rcu(nd);

@@ -926,6 +927,7 @@ static int follow_dotdot_rcu(struct name
struct dentry *parent = old->d_parent;
unsigned seq;

+ inode = parent->d_inode;
seq = read_seqcount_begin(&parent->d_seq);
if (read_seqcount_retry(&old->d_seq, nd->seq))
goto failed;
@@ -935,6 +937,7 @@ static int follow_dotdot_rcu(struct name
}
if (!follow_up_rcu(&nd->path))
break;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
while (d_mountpoint(nd->path.dentry)) {
@@ -944,9 +947,10 @@ static int follow_dotdot_rcu(struct name
break;
nd->path.mnt = mounted;
nd->path.dentry = mounted->mnt_root;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
- nd->inode = nd->path.dentry->d_inode;
+ nd->inode = inode;
return 0;

failed:
@@ -1556,7 +1560,14 @@ static int path_init(int dfd, const char
}

nd->inode = nd->path.dentry->d_inode;
- return 0;
+ if (!(flags & LOOKUP_RCU))
+ return 0;
+ if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
+ return 0;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ return -ECHILD;

fput_fail:
fput_light(file, fput_needed);


\
 
 \ /
  Last update: 2014-11-02 00:01    [W:0.410 / U:1.836 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site