3.2.43-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Ming Lei <ming....@canonical.com>
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 <da...@redhat.com>
Tested-by: Sasha Levin <levinsasha...@gmail.com>
Signed-off-by: Ming Lei <ming....@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
[bwh: Backported to 3.2: open-code file_inode() which we don't have]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
fs/sysfs/dir.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -1023,10 +1023,21 @@ 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->f_path.dentry->d_inode;
+ 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,
};
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