linux-kernel - [PATCH] ceph: Fix uninitialized dentry pointer in ceph_real

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Date:   Thu, 13 Oct 2016 17:15:37 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Zheng Yan <zyan@...hat.com>, Ilya Dryomov <idryomov@...il.com>
Cc:     ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH] ceph: Fix uninitialized dentry pointer in ceph_real_mount()

    fs/ceph/super.c: In function ‘ceph_real_mount’:
    fs/ceph/super.c:818: warning: ‘root’ may be used uninitialized in this function

If s_root is already valid, dentry pointer root is never initialized,
and returned by ceph_real_mount(). This will cause a crash later when
the caller dereferences the pointer.

Fix this by initializing root early.

Fixes: ce2728aaa82bbeba ("ceph: avoid accessing / when mounting a subpath")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
Compile-tested only.
---
 fs/ceph/super.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index a29ffce981879d5f..794c5fd0e0cf5e45 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -821,7 +821,8 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc)
 	dout("mount start %p\n", fsc);
 	mutex_lock(&fsc->client->mount_mutex);
 
-	if (!fsc->sb->s_root) {
+	root = fsc->sb->s_root;
+	if (!root) {
 		const char *path;
 		err = __ceph_open_session(fsc->client, started);
 		if (err < 0)
-- 
1.9.1