From: Dmitry Monakhov dmonakhov@openvz.org
[ Upstream commit f11b55d13563e9428c88c873f4f03a6bef11ec0a ]
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/e11a1b7b907ca67b1be51a159402560... Signed-off-by: Dmitry Monakhov dmonakhov@openvz.org Signed-off-by: Nicholas Bellinger nab@linux-iscsi.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/target/target_core_file.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c index 2e35db7f4aac..c15af2fcf2ba 100644 --- a/drivers/target/target_core_file.c +++ b/drivers/target/target_core_file.c @@ -276,12 +276,11 @@ 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 { /* @@ -294,17 +293,29 @@ 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