[PATCH AUTOSEL 4.19 15/21] jfs: fix array-index-out-of-bounds in jfs_readdir

[Sasha Levin <sashal@kernel.org>]

From: Ghanshyam Agrawal <ghanshyam1898@gmail.com>

[ Upstream commit 839f102efb168f02dfdd46717b7c6dddb26b015e ]

The stbl might contain some invalid values. Added a check to
return error code in that case.

Reported-by: syzbot+0315f8fe99120601ba88@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=0315f8fe99120601ba88
Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/jfs/jfs_dtree.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index a2186b6f274a7..cedbef8045cb9 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -3200,6 +3200,14 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
 		stbl = DT_GETSTBL(p);
 
 		for (i = index; i < p->header.nextindex; i++) {
+			if (stbl[i] < 0 || stbl[i] > 127) {
+				jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
+					i, stbl[i], (long)ip->i_ino, (long long)bn);
+				free_page(dirent_buf);
+				DT_PUTPAGE(mp);
+				return -EIO;
+			}
+
 			d = (struct ldtentry *) & p->slot[stbl[i]];
 
 			if (((long) jfs_dirent + d->namlen + 1) >
-- 
2.43.0