This is a note to let you know that I've just added the patch titled
procfs: fix race between symlink removals and traversals
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
procfs-fix-race-between-symlink-removals-and-traversals.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7e0e953bb0cf649f93277ac8fb67ecbb7f7b04a9 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sat, 21 Feb 2015 22:16:11 -0500
Subject: procfs: fix race between symlink removals and traversals
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 7e0e953bb0cf649f93277ac8fb67ecbb7f7b04a9 upstream.
use_pde()/unuse_pde() in ->follow_link()/->put_link() resp.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/proc/generic.c | 12 ------------
fs/proc/inode.c | 21 +++++++++++++++++++++
fs/proc/internal.h | 1 +
3 files changed, 22 insertions(+), 12 deletions(-)
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -19,7 +19,6 @@
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/idr.h>
-#include <linux/namei.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
@@ -223,17 +222,6 @@ void proc_free_inum(unsigned int inum)
spin_unlock_irqrestore(&proc_inum_lock, flags);
}
-static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
- nd_set_link(nd, __PDE_DATA(dentry->d_inode));
- return NULL;
-}
-
-static const struct inode_operations proc_link_inode_operations = {
- .readlink = generic_readlink,
- .follow_link = proc_follow_link,
-};
-
/*
* Don't create negative dentries here, return -ENOENT by hand
* instead.
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -23,6 +23,7 @@
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/magic.h>
+#include <linux/namei.h>
#include <asm/uaccess.h>
@@ -393,6 +394,26 @@ static const struct file_operations proc
};
#endif
+static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ struct proc_dir_entry *pde = PDE(dentry->d_inode);
+ if (unlikely(!use_pde(pde)))
+ return ERR_PTR(-EINVAL);
+ nd_set_link(nd, pde->data);
+ return pde;
+}
+
+static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
+{
+ unuse_pde(p);
+}
+
+const struct inode_operations proc_link_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = proc_follow_link,
+ .put_link = proc_put_link,
+};
+
struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
{
struct inode *inode = new_inode_pseudo(sb);
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -200,6 +200,7 @@ struct pde_opener {
int closing;
struct completion *c;
};
+extern const struct inode_operations proc_link_inode_operations;
extern const struct inode_operations proc_pid_link_inode_operations;
Patches currently in stable-queue which might be from viro@xxxxxxxxxxxxxxxxxx are
queue-3.19/procfs-fix-race-between-symlink-removals-and-traversals.patch
queue-3.19/debugfs-leave-freeing-a-symlink-body-until-inode-eviction.patch
queue-3.19/autofs4-copy_dev_ioctl-keep-the-value-of-size-we-d-used-for-allocation.patch
queue-3.19/autofs4-wrong-format-for-printing-dentry.patch
queue-3.19/sunrpc-fix-braino-in-poll.patch
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