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jfs: prevent NULL deref in diFree
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>
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YunDingLab authored and kleikamp committed Mar 22, 2022
1 parent 2cc7cc0 commit a530462
Showing 1 changed file with 2 additions and 1 deletion.
3 changes: 2 additions & 1 deletion fs/jfs/inode.c
Expand Up @@ -146,12 +146,13 @@ 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);

/*
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