From e5110f411d2ee35bf8d202ccca2e89c633060dca Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@canonical.com>
Date: Wed, 20 Mar 2013 23:25:25 +0800
Subject: [PATCH] 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>
---
fs/sysfs/dir.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index c9e16608f486a..e14512678c9b7 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -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);
--
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