Re: [PATCH] jfs: Fix array-index-out-of-bounds in diFree

[Jeongjun Park <aha310510@gmail.com>]

>
> Matthew Wilcox wrote:
> > This is not a good commit message.
>
> > > +   if(agno >= MAXAG || agno < 0)
> >
> > Please follow normal kernel whitespace rules -- one space between 'if'
> > and the open paren.
>
> Has confirmed. This is a patch that re-edited the relevant part to
> comply with the rules.
>
> Thanks.
>

I have just discovered that the patch I sent last time has been left 
unattended. It appears that the vulnerability continues to occur in 
version 6.10.0-rc1. I would appreciate it if you could review the patch
and let me know what might be wrong with it.

Regards

Reported-by: syzbot+241c815bda521982cb49@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
 fs/jfs/jfs_imap.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 2ec35889ad24..1407feccbc2d 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -290,7 +290,7 @@ int diSync(struct inode *ipimap)
 int diRead(struct inode *ip)
 {
 	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
-	int iagno, ino, extno, rc;
+	int iagno, ino, extno, rc, agno;
 	struct inode *ipimap;
 	struct dinode *dp;
 	struct iag *iagp;
@@ -339,8 +339,11 @@ int diRead(struct inode *ip)
 
 	/* get the ag for the iag */
 	agstart = le64_to_cpu(iagp->agstart);
+	agno = BLKTOAG(agstart, JFS_SBI(ip->i_sb));
 
 	release_metapage(mp);
+	if (agno >= MAXAG || agno < 0)
+		return -EIO;
 
 	rel_inode = (ino & (INOSPERPAGE - 1));
 	pageno = blkno >> sbi->l2nbperpage;
-- 
2.34.1