[PATCH] fs/proc: Fix NULL pointer dereference in pid_delete_dentry

From: Yahu Gao
Date: Wed Dec 09 2020 - 06:22:56 EST


Get the staus of task from the pointer of proc inode directly is not
safe. The function get_proc_task make it happen in RCU protection.

Signed-off-by: Yahu Gao <yahu.gao@xxxxxxxxxxxxx>
---
fs/proc/base.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1bc9bcdef09f..05f33bb35067 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1994,7 +1994,7 @@ static int pid_revalidate(struct dentry *dentry, unsigned int flags)

static inline bool proc_inode_is_dead(struct inode *inode)
{
- return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
+ return !get_proc_task(inode);
}

int pid_delete_dentry(const struct dentry *dentry)
--
2.25.1