[PATCH 4.14 234/284] jfs: prevent NULL deref in diFree

Greg Kroah-Hartman
2022-04-18T13:59:05Z

From: Haimin Zhang <tcs_kernel@tencent.com>

[ Upstream commit a53046291020ec41e09181396c1e829287b48d47 ]

Add validation check for JFS_IP(ipimap)->i_imap to prevent a NULL deref
in diFree since diFree uses it without do any validations.
When function jfs_mount calls diMount to initialize fileset inode
allocation map, it can fail and JFS_IP(ipimap)->i_imap won't be
initialized. Then it calls diFreeSpecial to close fileset inode allocation
map inode and it will flow into jfs_evict_inode. Function jfs_evict_inode
just validates JFS_SBI(inode->i_sb)->ipimap, then calls diFree. diFree use
JFS_IP(ipimap)->i_imap directly, then it will cause a NULL deref.

Reported-by: TCS Robot <tcs_robot@tencent.com>
Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/jfs/inode.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/inode.c b/fs/jfs/inode.c
index 87b41edc800d..68779cc3609a 100644
--- a/fs/jfs/inode.c
+++ b/fs/jfs/inode.c
@@ -156,12 +156,13 @@ void jfs_evict_inode(struct inode *inode)
dquot_initialize(inode);

if (JFS_IP(inode)->fileset == FILESYSTEM_I) {
+ struct inode *ipimap = JFS_SBI(inode->i_sb)->ipimap;
truncate_inode_pages_final(&inode->i_data);

if (test_cflag(COMMIT_Freewmap, inode))
jfs_free_zero_link(inode);

- if (JFS_SBI(inode->i_sb)->ipimap)
+ if (ipimap && JFS_IP(ipimap)->i_imap)
diFree(inode);

/*
--
2.35.1