[PATCH AUTOSEL 4.19 05/12] jfs: fix uaf in jfs_evict_inode

[Sasha Levin <sashal@kernel.org>]

From: Edward Adam Davis <eadavis@qq.com>

[ Upstream commit e0e1958f4c365e380b17ccb35617345b31ef7bf3 ]

When the execution of diMount(ipimap) fails, the object ipimap that has been
released may be accessed in diFreeSpecial(). Asynchronous ipimap release occurs
when rcu_core() calls jfs_free_node().

Therefore, when diMount(ipimap) fails, sbi->ipimap should not be initialized as
ipimap.

Reported-and-tested-by: syzbot+01cf2dbcbe2022454388@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/jfs/jfs_mount.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/jfs/jfs_mount.c b/fs/jfs/jfs_mount.c
index f1a705d15904..97d91c1686b8 100644
--- a/fs/jfs/jfs_mount.c
+++ b/fs/jfs/jfs_mount.c
@@ -184,15 +184,15 @@ int jfs_mount(struct super_block *sb)
 	}
 	jfs_info("jfs_mount: ipimap:0x%p", ipimap);
 
-	/* map further access of per fileset inodes by the fileset inode */
-	sbi->ipimap = ipimap;
-
 	/* initialize fileset inode allocation map */
 	if ((rc = diMount(ipimap))) {
 		jfs_err("jfs_mount: diMount failed w/rc = %d", rc);
 		goto err_ipimap;
 	}
 
+	/* map further access of per fileset inodes by the fileset inode */
+	sbi->ipimap = ipimap;
+
 	return rc;
 
 	/*
-- 
2.43.0