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Commit 5559b8f4 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
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fuse: fix race in llseek 



Fuse doesn't use i_mutex to protect setting i_size, and so
generic_file_llseek() can be racy: it doesn't use i_size_read().

So do a fuse specific llseek method, which does use i_size_read().

[akpm@linux-foundation.org: make `retval' loff_t]
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b48badf0

fs/fuse/file.c

+27 −2
Original line number Diff line number Diff line
@@ -1431,8 +1431,33 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block) 
	return err ? 0 : outarg.block;

}



static loff_t fuse_file_llseek(struct file *file, loff_t offset, int origin)

{

	loff_t retval;

	struct inode *inode = file->f_path.dentry->d_inode;



	mutex_lock(&inode->i_mutex);

	switch (origin) {

	case SEEK_END:

		offset += i_size_read(inode);

		break;

	case SEEK_CUR:

		offset += file->f_pos;

	}

	retval = -EINVAL;

	if (offset >= 0 && offset <= inode->i_sb->s_maxbytes) {

		if (offset != file->f_pos) {

			file->f_pos = offset;

			file->f_version = 0;

		}

		retval = offset;

	}

	mutex_unlock(&inode->i_mutex);

	return retval;

}



static const struct file_operations fuse_file_operations = {

	.llseek		= generic_file_llseek,

	.llseek		= fuse_file_llseek,

	.read		= do_sync_read,

	.aio_read	= fuse_file_aio_read,

	.write		= do_sync_write,
@@ -1448,7 +1473,7 @@ static const struct file_operations fuse_file_operations = { 
};



static const struct file_operations fuse_direct_io_file_operations = {

	.llseek		= generic_file_llseek,

	.llseek		= fuse_file_llseek,

	.read		= fuse_direct_read,

	.write		= fuse_direct_write,

	.open		= fuse_open,