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authorChen Zhongjin <chenzhongjin@huawei.com>2022-11-28 13:33:05 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2022-11-28 13:33:05 +0300
commit672e4268b2863d7e4978dfed29552b31c2f9bd4e (patch)
tree68402976a308f4f3632a8b4ed2e9639b50812ad7 /fs/overlayfs
parenteb7081409f94a9a8608593d0fb63a1aa3d6f95d8 (diff)
downloadlinux-672e4268b2863d7e4978dfed29552b31c2f9bd4e.tar.xz
ovl: fix use inode directly in rcu-walk mode
ovl_dentry_revalidate_common() can be called in rcu-walk mode. As document said, "in rcu-walk mode, d_parent and d_inode should not be used without care". Check inode here to protect access under rcu-walk mode. Fixes: bccece1ead36 ("ovl: allow remote upper") Reported-and-tested-by: syzbot+a4055c78774bbf3498bb@syzkaller.appspotmail.com Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com> Cc: <stable@vger.kernel.org> # v5.7 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/super.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index a29a8afe9b26..3d14a3f1465d 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -139,11 +139,16 @@ static int ovl_dentry_revalidate_common(struct dentry *dentry,
unsigned int flags, bool weak)
{
struct ovl_entry *oe = dentry->d_fsdata;
+ struct inode *inode = d_inode_rcu(dentry);
struct dentry *upper;
unsigned int i;
int ret = 1;
- upper = ovl_dentry_upper(dentry);
+ /* Careful in RCU mode */
+ if (!inode)
+ return -ECHILD;
+
+ upper = ovl_i_dentry_upper(inode);
if (upper)
ret = ovl_revalidate_real(upper, flags, weak);