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Commit f11b55d1 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Nicholas Bellinger
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tcm_fileio: Prevent information leak for short reads 

If we failed to read data from backing file (probably because some one
truncate file under us), we must zerofill cmd's data, otherwise it will
be returned as is. Most likely cmd's data are unitialized pages from
page cache. This result in information leak.

(Change BUG_ON into -EINVAL se_cmd failure - nab)

testcase: https://github.com/dmonakhov/xfstests/commit/e11a1b7b907ca67b1be51a1594025600767366d5


Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 0e2eb7d1

drivers/target/target_core_file.c

+17 −6
Original line number Diff line number Diff line
@@ -277,12 +277,11 @@ static int fd_do_rw(struct se_cmd *cmd, struct file *fd, 
	else

		ret = vfs_iter_read(fd, &iter, &pos);



	kfree(bvec);



	if (is_write) {

		if (ret < 0 || ret != data_length) {

			pr_err("%s() write returned %d\n", __func__, ret);

			return (ret < 0 ? ret : -EINVAL);

			if (ret >= 0)

				ret = -EINVAL;

		}

	} else {

		/*
@@ -295,17 +294,29 @@ static int fd_do_rw(struct se_cmd *cmd, struct file *fd, 
				pr_err("%s() returned %d, expecting %u for "

						"S_ISBLK\n", __func__, ret,

						data_length);

				return (ret < 0 ? ret : -EINVAL);

				if (ret >= 0)

					ret = -EINVAL;

			}

		} else {

			if (ret < 0) {

				pr_err("%s() returned %d for non S_ISBLK\n",

						__func__, ret);

				return ret;

			} else if (ret != data_length) {

				/*

				 * Short read case:

				 * Probably some one truncate file under us.

				 * We must explicitly zero sg-pages to prevent

				 * expose uninizialized pages to userspace.

				 */

				if (ret < data_length)

					ret += iov_iter_zero(data_length - ret, &iter);

				else

					ret = -EINVAL;

			}

		}

	}

	return 1;

	kfree(bvec);

	return ret;

}



static sense_reason_t