lkml.org 
[lkml]   [2018]   [Dec]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 45/46] proc/sysctl: dont return ENOMEM on lookup when a table is unregistering
    Date
    4.19-stable review patch.  If anyone has any objections, please let me know.

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

    From: Ivan Delalande <colona@arista.com>

    commit ea5751ccd665a2fd1b24f9af81f6167f0718c5f6 upstream.

    proc_sys_lookup can fail with ENOMEM instead of ENOENT when the
    corresponding sysctl table is being unregistered. In our case we see
    this upon opening /proc/sys/net/*/conf files while network interfaces
    are being deleted, which confuses our configuration daemon.

    The problem was successfully reproduced and this fix tested on v4.9.122
    and v4.20-rc6.

    v2: return ERR_PTRs in all cases when proc_sys_make_inode fails instead
    of mixing them with NULL. Thanks Al Viro for the feedback.

    Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.")
    Cc: stable@vger.kernel.org
    Signed-off-by: Ivan Delalande <colona@arista.com>
    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/proc/proc_sysctl.c | 13 ++++++-------
    1 file changed, 6 insertions(+), 7 deletions(-)

    --- a/fs/proc/proc_sysctl.c
    +++ b/fs/proc/proc_sysctl.c
    @@ -464,7 +464,7 @@ static struct inode *proc_sys_make_inode

    inode = new_inode(sb);
    if (!inode)
    - goto out;
    + return ERR_PTR(-ENOMEM);

    inode->i_ino = get_next_ino();

    @@ -474,8 +474,7 @@ static struct inode *proc_sys_make_inode
    if (unlikely(head->unregistering)) {
    spin_unlock(&sysctl_lock);
    iput(inode);
    - inode = NULL;
    - goto out;
    + return ERR_PTR(-ENOENT);
    }
    ei->sysctl = head;
    ei->sysctl_entry = table;
    @@ -500,7 +499,6 @@ static struct inode *proc_sys_make_inode
    if (root->set_ownership)
    root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);

    -out:
    return inode;
    }

    @@ -549,10 +547,11 @@ static struct dentry *proc_sys_lookup(st
    goto out;
    }

    - err = ERR_PTR(-ENOMEM);
    inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
    - if (!inode)
    + if (IS_ERR(inode)) {
    + err = ERR_CAST(inode);
    goto out;
    + }

    d_set_d_op(dentry, &proc_sys_dentry_operations);
    err = d_splice_alias(inode, dentry);
    @@ -685,7 +684,7 @@ static bool proc_sys_fill_cache(struct f
    if (d_in_lookup(child)) {
    struct dentry *res;
    inode = proc_sys_make_inode(dir->d_sb, head, table);
    - if (!inode) {
    + if (IS_ERR(inode)) {
    d_lookup_done(child);
    dput(child);
    return false;

    \
     
     \ /
      Last update: 2018-12-28 13:16    [W:4.541 / U:0.348 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site