[Devel] [PATCH 2/5] sysfs/blk-sysfs: fix uninitialized var usage

[Dmitry Safonov]

One may write some shit to unpriv_sgio file (introduced by
import RHEL7 kernel-3.10.0-229.7.2.el7), which will result in corectness
check by function queue_var_store returning -EINVAL. Since return value
of this function is not checked in queue_store_unpriv_sgio, function may
result in random QUEUE_FLAG_UNPRIV_SGIO flag value.
Since it's all done under CAP_SYS_ADMIN, it's not too critical.

Found by warning:
block/blk-sysfs.c: In function ‘queue_store_unpriv_sgio’:
block/blk-sysfs.c:211:5: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  if (val)

Signed-off-by: Dmitry Safonov <dsafonov at odin.com>
---
 block/blk-sysfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 21bc0c7..c08d91c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -207,6 +207,9 @@ queue_store_unpriv_sgio(struct request_queue *q, const char *page, size_t count)
 		return -EPERM;
 
 	ret = queue_var_store(&val, page, count);
+	if (ret < 0)
+		return ret;
+
 	spin_lock_irq(q->queue_lock);
 	if (val)
 		queue_flag_set(QUEUE_FLAG_UNPRIV_SGIO, q);
-- 
2.7.0