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authorOmar Sandoval <osandov@fb.com>2018-04-06 09:57:03 -0700
committerJens Axboe <axboe@kernel.dk>2018-04-10 08:38:46 -0600
commitbdac616db9bbadb90b7d6a406144571015e138f7 (patch)
treed883f14fdc2dc308c13aae0cf80042deec2ffd6b /drivers/block/loop.c
parent1e047eaab3bb5564f25b41e9cd3a053009f4e789 (diff)
loop: fix LOOP_GET_STATUS lock imbalance
Commit 2d1d4c1e591f 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: 2d1d4c1e591f ("loop: don't call into filesystem while holding lo_ctl_mutex") Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r--drivers/block/loop.c33
1 files changed, 18 insertions, 15 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e5fc020cceda..c9d04497a415 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1287,12 +1287,13 @@ static int
loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
struct loop_info info;
struct loop_info64 info64;
- int err = 0;
+ int err;
- if (!arg)
- err = -EINVAL;
- if (!err)
- err = loop_get_status(lo, &info64);
+ if (!arg) {
+ mutex_unlock(&lo->lo_ctl_mutex);
+ return -EINVAL;
+ }
+ err = loop_get_status(lo, &info64);
if (!err)
err = loop_info64_to_old(&info64, &info);
if (!err && copy_to_user(arg, &info, sizeof(info)))
@@ -1304,12 +1305,13 @@ loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
static int
loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
struct loop_info64 info64;
- int err = 0;
+ int err;
- if (!arg)
- err = -EINVAL;
- if (!err)
- err = loop_get_status(lo, &info64);
+ if (!arg) {
+ mutex_unlock(&lo->lo_ctl_mutex);
+ return -EINVAL;
+ }
+ err = loop_get_status(lo, &info64);
if (!err && copy_to_user(arg, &info64, sizeof(info64)))
err = -EFAULT;
@@ -1533,12 +1535,13 @@ loop_get_status_compat(struct loop_device *lo,
struct compat_loop_info __user *arg)
{
struct loop_info64 info64;
- int err = 0;
+ int err;
- if (!arg)
- err = -EINVAL;
- if (!err)
- err = loop_get_status(lo, &info64);
+ if (!arg) {
+ mutex_unlock(&lo->lo_ctl_mutex);
+ return -EINVAL;
+ }
+ err = loop_get_status(lo, &info64);
if (!err)
err = loop_info64_to_compat(&info64, arg);
return err;