From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
fs_name() has @index as unsigned int, so there is underflow risk for
operation '@index--'.
Fix by breaking the for loop when '@index == 0' which is also more proper
than '@index <= 0' for unsigned integer comparison.
Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
---
fs/filesystems.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/fs/filesystems.c b/fs/filesystems.c
index 58b9067b2391ce814e580709b518b405e0f9cb8a..95e5256821a53494d88f496193305a2e50e04444 100644
--- a/fs/filesystems.c
+++ b/fs/filesystems.c
@@ -156,15 +156,19 @@ static int fs_index(const char __user * __name)
static int fs_name(unsigned int index, char __user * buf)
{
struct file_system_type * tmp;
- int len, res;
+ int len, res = -EINVAL;
read_lock(&file_systems_lock);
- for (tmp = file_systems; tmp; tmp = tmp->next, index--)
- if (index <= 0 && try_module_get(tmp->owner))
+ for (tmp = file_systems; tmp; tmp = tmp->next, index--) {
+ if (index == 0) {
+ if (try_module_get(tmp->owner))
+ res = 0;
break;
+ }
+ }
read_unlock(&file_systems_lock);
- if (!tmp)
- return -EINVAL;
+ if (res)
+ return res;
/* OK, we got the reference, so we can safely block */
len = strlen(tmp->name) + 1;
--
2.34.1
