Commit bdac616d authored by Omar Sandoval's avatar Omar Sandoval Committed by Jens Axboe

loop: fix LOOP_GET_STATUS lock imbalance

Commit 2d1d4c1e made loop_get_status() drop lo_ctx_mutex before
returning, but the loop_get_status_old(), loop_get_status64(), and
loop_get_status_compat() wrappers don't call loop_get_status() if the
passed argument is NULL. The callers expect that the lock is dropped, so
make sure we drop it in that case, too.

Reported-by: syzbot+31e8daa8b3fc129e75f2@syzkaller.appspotmail.com
Fixes: 2d1d4c1e ("loop: don't call into filesystem while holding lo_ctl_mutex")
Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1e047eaa
...@@ -1287,11 +1287,12 @@ static int ...@@ -1287,11 +1287,12 @@ static int
loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
struct loop_info info; struct loop_info info;
struct loop_info64 info64; struct loop_info64 info64;
int err = 0; int err;
if (!arg) if (!arg) {
err = -EINVAL; mutex_unlock(&lo->lo_ctl_mutex);
if (!err) return -EINVAL;
}
err = loop_get_status(lo, &info64); err = loop_get_status(lo, &info64);
if (!err) if (!err)
err = loop_info64_to_old(&info64, &info); err = loop_info64_to_old(&info64, &info);
...@@ -1304,11 +1305,12 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { ...@@ -1304,11 +1305,12 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
static int static int
loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
struct loop_info64 info64; struct loop_info64 info64;
int err = 0; int err;
if (!arg) if (!arg) {
err = -EINVAL; mutex_unlock(&lo->lo_ctl_mutex);
if (!err) return -EINVAL;
}
err = loop_get_status(lo, &info64); err = loop_get_status(lo, &info64);
if (!err && copy_to_user(arg, &info64, sizeof(info64))) if (!err && copy_to_user(arg, &info64, sizeof(info64)))
err = -EFAULT; err = -EFAULT;
...@@ -1533,11 +1535,12 @@ loop_get_status_compat(struct loop_device *lo, ...@@ -1533,11 +1535,12 @@ loop_get_status_compat(struct loop_device *lo,
struct compat_loop_info __user *arg) struct compat_loop_info __user *arg)
{ {
struct loop_info64 info64; struct loop_info64 info64;
int err = 0; int err;
if (!arg) if (!arg) {
err = -EINVAL; mutex_unlock(&lo->lo_ctl_mutex);
if (!err) return -EINVAL;
}
err = loop_get_status(lo, &info64); err = loop_get_status(lo, &info64);
if (!err) if (!err)
err = loop_info64_to_compat(&info64, arg); err = loop_info64_to_compat(&info64, arg);
......
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