From cde9833c97c4ad06e569e1f0e7e6b1c84c948aa3 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Wed, 20 Mar 2013 23:25:25 +0800 Subject: sysfs: handle failure path correctly for readdir() commit e5110f411d2ee35bf8d202ccca2e89c633060dca upstream. 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 Tested-by: Sasha Levin Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/dir.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'fs') diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index f8ca94cb7e8..45024ef34fd 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -1002,6 +1002,8 @@ 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) @@ -1010,6 +1012,8 @@ 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); -- cgit v1.2.3-18-g5258