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From:   Manas Ghandat <ghandatmanas@gmail.com>
To:     dave.kleikamp@oracle.com, shaggy@kernel.org
Cc:     Manas Ghandat <ghandatmanas@gmail.com>,
        Linux-kernel-mentees@lists.linuxfoundation.org,
        jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org,
        syzbot+c1056fdfe414463fdb33@syzkaller.appspotmail.com
Subject: [PATCH] jfs : fix array-index-out-of-bounds in diWrite
Date:   Sun,  8 Oct 2023 23:17:45 +0530
Message-Id: <20231008174745.27342-1-ghandatmanas@gmail.com>
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Currently while copying dtree root from inode to dnode in the xp slot
there is a out of bound memcpy. Added a bound check to the memcpy.

Reported-by: syzbot+c1056fdfe414463fdb33@syzkaller.appspotmail.com
Fixes: https://syzkaller.appspot.com/bug?extid=c1056fdfe414463fdb33
Signed-off-by: Manas Ghandat <ghandatmanas@gmail.com>
---
 fs/jfs/jfs_imap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 799d3837e7c2..d1f897848be0 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -746,7 +746,8 @@ int diWrite(tid_t tid, struct inode *ip)
 		xp = (dtpage_t *) & dp->di_dtroot;
 		lv = ilinelock->lv;
 		for (n = 0; n < ilinelock->index; n++, lv++) {
-			memcpy(&xp->slot[lv->offset], &p->slot[lv->offset],
+			if (lv->offset < 128)
+				memcpy(&xp->slot[lv->offset], &p->slot[lv->offset],
 			       lv->length << L2DTSLOTSIZE);
 		}
 	} else {
-- 
2.37.2