lkml.org 
[lkml]   [2014]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3.13 068/163] be careful with nd->inode in path_init() and follow_dotdot_rcu()
    Date
    3.13.11.9 -stable 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>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    fs/namei.c | 15 +++++++++++++--
    1 file changed, 13 insertions(+), 2 deletions(-)

    diff --git a/fs/namei.c b/fs/namei.c
    index aed3458..eaabb52 100644
    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -1119,6 +1119,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,

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

    @@ -1132,6 +1133,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
    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;
    @@ -1141,6 +1143,7 @@ static int follow_dotdot_rcu(struct nameidata *nd)
    }
    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)) {
    @@ -1150,11 +1153,12 @@ static int follow_dotdot_rcu(struct nameidata *nd)
    break;
    nd->path.mnt = &mounted->mnt;
    nd->path.dentry = mounted->mnt.mnt_root;
    + inode = nd->path.dentry->d_inode;
    nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
    if (!read_seqretry(&mount_lock, nd->m_seq))
    goto failed;
    }
    - nd->inode = nd->path.dentry->d_inode;
    + nd->inode = inode;
    return 0;

    failed:
    @@ -1883,7 +1887,14 @@ static int path_init(int dfd, const char *name, unsigned int flags,
    }

    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;
    }

    static inline int lookup_last(struct nameidata *nd, struct path *path)
    --
    1.9.1


    \
     
     \ /
      Last update: 2014-10-09 23:42    [W:4.525 / U:0.256 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site