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sysfs: handle failure path correctly for readdir() 

In case of 'if (filp->f_pos ==  0 or 1)' of sysfs_readdir(),
the failure from filldir() isn't handled, and the reference counter
of the sysfs_dirent object pointed by filp->private_data will be
released without clearing filp->private_data, so use after free
bug will be triggered later.

This patch returns immeadiately under the situation for fixing the bug,
and it is reasonable to return from readdir() when filldir() fails.

Reported-by: Dave Jones <davej@redhat.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ming Lei 2013-03-20 23:25:25 +08:00 committed by Greg Kroah-Hartman
parent 991f76f837
commit e5110f411d
1 changed files with 4 additions and 0 deletions
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4
fs/sysfs/dir.c
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@ -1020,6 +1020,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
ino = parent_sd->s_ino;
if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
filp->f_pos++;
else
return 0;
}
if (filp->f_pos == 1) {
if (parent_sd->s_parent)
@ -1028,6 +1030,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
ino = parent_sd->s_ino;
if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
filp->f_pos++;
else
return 0;
}
mutex_lock(&sysfs_mutex);
for (pos = sysfs_dir_pos(ns, parent_sd, filp->f_pos, pos);