[PATCH AUTOSEL 4.19 2/5] reiserfs: add check for root_inode in reiserfs_fill_super

[PATCH AUTOSEL 4.19 2/5] reiserfs: add check for root_inode in reiserfs_fill_super

[Sasha Levin]

From: Yu Kuai <yukuai3@huawei.com>

[ Upstream commit 2acf15b94d5b8ea8392c4b6753a6ffac3135cd78 ]

Our syzcaller report a NULL pointer dereference:

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 116e95067 P4D 116e95067 PUD 1080b5067 PMD 0
Oops: 0010 [#1] SMP KASAN
CPU: 7 PID: 592 Comm: a.out Not tainted 5.13.0-next-20210629-dirty #67
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-p4
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffff888114e779b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff110229cef39 RCX: ffffffffaa67e1aa
RDX: 0000000000000000 RSI: ffff88810a58ee00 RDI: ffff8881233180b0
RBP: ffffffffac38e9c0 R08: ffffffffaa67e17e R09: 0000000000000001
R10: ffffffffb91c5557 R11: fffffbfff7238aaa R12: ffff88810a58ee00
R13: ffff888114e77aa0 R14: 0000000000000000 R15: ffff8881233180b0
FS:  00007f946163c480(0000) GS:ffff88839f1c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001099c1000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __lookup_slow+0x116/0x2d0
 ? page_put_link+0x120/0x120
 ? __d_lookup+0xfc/0x320
 ? d_lookup+0x49/0x90
 lookup_one_len+0x13c/0x170
 ? __lookup_slow+0x2d0/0x2d0
 ? reiserfs_schedule_old_flush+0x31/0x130
 reiserfs_lookup_privroot+0x64/0x150
 reiserfs_fill_super+0x158c/0x1b90
 ? finish_unfinished+0xb10/0xb10
 ? bprintf+0xe0/0xe0
 ? __mutex_lock_slowpath+0x30/0x30
 ? __kasan_check_write+0x20/0x30
 ? up_write+0x51/0xb0
 ? set_blocksize+0x9f/0x1f0
 mount_bdev+0x27c/0x2d0
 ? finish_unfinished+0xb10/0xb10
 ? reiserfs_kill_sb+0x120/0x120
 get_super_block+0x19/0x30
 legacy_get_tree+0x76/0xf0
 vfs_get_tree+0x49/0x160
 ? capable+0x1d/0x30
 path_mount+0xacc/0x1380
 ? putname+0x97/0xd0
 ? finish_automount+0x450/0x450
 ? kmem_cache_free+0xf8/0x5a0
 ? putname+0x97/0xd0
 do_mount+0xe2/0x110
 ? path_mount+0x1380/0x1380
 ? copy_mount_options+0x69/0x140
 __x64_sys_mount+0xf0/0x190
 do_syscall_64+0x35/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

This is because 'root_inode' is initialized with wrong mode, and
it's i_op is set to 'reiserfs_special_inode_operations'. Thus add
check for 'root_inode' to fix the problem.

Link: https://lore.kernel.org/r/20210702040743.1918552-1-yukuai3@huawei.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/reiserfs/super.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index ec5716dd58c2..831a542c22c6 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -2085,6 +2085,14 @@ static int reiserfs_fill_super(struct super_block *s, void *data, int silent)
 		unlock_new_inode(root_inode);
 	}
 
+	if (!S_ISDIR(root_inode->i_mode) || !inode_get_bytes(root_inode) ||
+	    !root_inode->i_size) {
+		SWARN(silent, s, "", "corrupt root inode, run fsck");
+		iput(root_inode);
+		errval = -EUCLEAN;
+		goto error;
+	}
+
 	s->s_root = d_make_root(root_inode);
 	if (!s->s_root)
 		goto error;
-- 
2.30.2

[PATCH AUTOSEL 4.19 3/5] reiserfs: check directory items on read from disk

[Sasha Levin]

From: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>

[ Upstream commit 13d257503c0930010ef9eed78b689cec417ab741 ]

While verifying the leaf item that we read from the disk, reiserfs
doesn't check the directory items, this could cause a crash when we
read a directory item from the disk that has an invalid deh_location.

This patch adds a check to the directory items read from the disk that
does a bounds check on deh_location for the directory entries. Any
directory entry header with a directory entry offset greater than the
item length is considered invalid.

Link: https://lore.kernel.org/r/20210709152929.766363-1-chouhan.shreyansh630@gmail.com
Reported-by: syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/reiserfs/stree.c | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/fs/reiserfs/stree.c b/fs/reiserfs/stree.c
index 5229038852ca..4ebad6781b0e 100644
--- a/fs/reiserfs/stree.c
+++ b/fs/reiserfs/stree.c
@@ -387,6 +387,24 @@ void pathrelse(struct treepath *search_path)
 	search_path->path_length = ILLEGAL_PATH_ELEMENT_OFFSET;
 }
 
+static int has_valid_deh_location(struct buffer_head *bh, struct item_head *ih)
+{
+	struct reiserfs_de_head *deh;
+	int i;
+
+	deh = B_I_DEH(bh, ih);
+	for (i = 0; i < ih_entry_count(ih); i++) {
+		if (deh_location(&deh[i]) > ih_item_len(ih)) {
+			reiserfs_warning(NULL, "reiserfs-5094",
+					 "directory entry location seems wrong %h",
+					 &deh[i]);
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
 static int is_leaf(char *buf, int blocksize, struct buffer_head *bh)
 {
 	struct block_head *blkh;
@@ -454,11 +472,14 @@ static int is_leaf(char *buf, int blocksize, struct buffer_head *bh)
 					 "(second one): %h", ih);
 			return 0;
 		}
-		if (is_direntry_le_ih(ih) && (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE))) {
-			reiserfs_warning(NULL, "reiserfs-5093",
-					 "item entry count seems wrong %h",
-					 ih);
-			return 0;
+		if (is_direntry_le_ih(ih)) {
+			if (ih_item_len(ih) < (ih_entry_count(ih) * IH_SIZE)) {
+				reiserfs_warning(NULL, "reiserfs-5093",
+						 "item entry count seems wrong %h",
+						 ih);
+				return 0;
+			}
+			return has_valid_deh_location(bh, ih);
 		}
 		prev_location = ih_location(ih);
 	}
-- 
2.30.2