This is a note to let you know that I've just added the patch titled
sysfs: fix race between readdir and lseek
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sysfs-fix-race-between-readdir-and-lseek.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 991f76f837bf22c5bb07261cfd86525a0a96650c Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Date: Wed, 20 Mar 2013 23:25:24 +0800
Subject: sysfs: fix race between readdir and lseek
From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
commit 991f76f837bf22c5bb07261cfd86525a0a96650c upstream.
While readdir() is running, lseek() may set filp->f_pos as zero,
then may leave filp->private_data pointing to one sysfs_dirent
object without holding its reference counter, so the sysfs_dirent
object may be used after free in next readdir().
This patch holds inode->i_mutex to avoid the problem since
the lock is always held in readdir path.
Reported-by: Dave Jones <davej@xxxxxxxxxx>
Tested-by: Sasha Levin <levinsasha928@xxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/sysfs/dir.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -1040,10 +1040,21 @@ static int sysfs_readdir(struct file * f
return 0;
}
+static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct inode *inode = file_inode(file);
+ loff_t ret;
+
+ mutex_lock(&inode->i_mutex);
+ ret = generic_file_llseek(file, offset, whence);
+ mutex_unlock(&inode->i_mutex);
+
+ return ret;
+}
const struct file_operations sysfs_dir_operations = {
.read = generic_read_dir,
.readdir = sysfs_readdir,
.release = sysfs_dir_release,
- .llseek = generic_file_llseek,
+ .llseek = sysfs_dir_llseek,
};
Patches currently in stable-queue which might be from ming.lei@xxxxxxxxxxxxx are
queue-3.4/bluetooth-add-support-for-dell.patch
queue-3.4/sysfs-handle-failure-path-correctly-for-readdir.patch
queue-3.4/bluetooth-add-support-for-dell_2.patch
queue-3.4/sysfs-fix-race-between-readdir-and-lseek.patch
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