linux-kernel - [PATCH 6.6.y] jfs: reject on-disk inodes of an unsupported type

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Message-Id: <20250727095645.530309-1-duttaditya18@gmail.com>
Date: Sun, 27 Jul 2025 15:26:45 +0530
From: Aditya Dutt <duttaditya18@...il.com>
To: stable@...r.kernel.org
Cc: Dmitry Antipov <dmantipov@...dex.ru>,
	Dave Kleikamp <dave.kleikamp@...cle.com>,
	Dave Kleikamp <shaggy@...nel.org>,
	skhan@...uxfoundation.org,
	linux-kernel@...r.kernel.org,
	linux-kernel-mentees@...ts.linux.dev,
	jfs-discussion@...ts.sourceforge.net,
	syzbot+ac2116e48989e84a2893@...kaller.appspotmail.com,
	Aditya Dutt <duttaditya18@...il.com>
Subject: [PATCH 6.6.y] jfs: reject on-disk inodes of an unsupported type

From: Dmitry Antipov <dmantipov@...dex.ru>

[ Upstream commit 8c3f9a70d2d4dd6c640afe294b05c6a0a45434d9 ]

Syzbot has reported the following BUG:

kernel BUG at fs/inode.c:668!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 3 UID: 0 PID: 139 Comm: jfsCommit Not tainted 6.12.0-rc4-syzkaller-00085-g4e46774408d9 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
RIP: 0010:clear_inode+0x168/0x190
Code: 4c 89 f7 e8 ba fe e5 ff e9 61 ff ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 7c c1 4c 89 f7 e8 90 ff e5 ff eb b7
 0b e8 01 5d 7f ff 90 0f 0b e8 f9 5c 7f ff 90 0f 0b e8 f1 5c 7f
RSP: 0018:ffffc900027dfae8 EFLAGS: 00010093
RAX: ffffffff82157a87 RBX: 0000000000000001 RCX: ffff888104d4b980
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900027dfc90 R08: ffffffff82157977 R09: fffff520004fbf38
R10: dffffc0000000000 R11: fffff520004fbf38 R12: dffffc0000000000
R13: ffff88811315bc00 R14: ffff88811315bda8 R15: ffff88811315bb80
FS:  0000000000000000(0000) GS:ffff888135f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005565222e0578 CR3: 0000000026ef0000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ? __die_body+0x5f/0xb0
 ? die+0x9e/0xc0
 ? do_trap+0x15a/0x3a0
 ? clear_inode+0x168/0x190
 ? do_error_trap+0x1dc/0x2c0
 ? clear_inode+0x168/0x190
 ? __pfx_do_error_trap+0x10/0x10
 ? report_bug+0x3cd/0x500
 ? handle_invalid_op+0x34/0x40
 ? clear_inode+0x168/0x190
 ? exc_invalid_op+0x38/0x50
 ? asm_exc_invalid_op+0x1a/0x20
 ? clear_inode+0x57/0x190
 ? clear_inode+0x167/0x190
 ? clear_inode+0x168/0x190
 ? clear_inode+0x167/0x190
 jfs_evict_inode+0xb5/0x440
 ? __pfx_jfs_evict_inode+0x10/0x10
 evict+0x4ea/0x9b0
 ? __pfx_evict+0x10/0x10
 ? iput+0x713/0xa50
 txUpdateMap+0x931/0xb10
 ? __pfx_txUpdateMap+0x10/0x10
 jfs_lazycommit+0x49a/0xb80
 ? _raw_spin_unlock_irqrestore+0x8f/0x140
 ? lockdep_hardirqs_on+0x99/0x150
 ? __pfx_jfs_lazycommit+0x10/0x10
 ? __pfx_default_wake_function+0x10/0x10
 ? __kthread_parkme+0x169/0x1d0
 ? __pfx_jfs_lazycommit+0x10/0x10
 kthread+0x2f2/0x390
 ? __pfx_jfs_lazycommit+0x10/0x10
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x4d/0x80
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

This happens when 'clear_inode()' makes an attempt to finalize an underlying
JFS inode of unknown type. According to JFS layout description from
https://jfs.sourceforge.net/project/pub/jfslayout.pdf, inode types from 5 to
15 are reserved for future extensions and should not be encountered on a valid
filesystem. So add an extra check for valid inode type in 'copy_from_dinode()'.

Reported-by: syzbot+ac2116e48989e84a2893@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ac2116e48989e84a2893
Fixes: 79ac5a46c5c1 ("jfs_lookup(): don't bother with . or ..")
Signed-off-by: Dmitry Antipov <dmantipov@...dex.ru>
Signed-off-by: Dave Kleikamp <dave.kleikamp@...cle.com>
Signed-off-by: Aditya Dutt <duttaditya18@...il.com>
---

As per: https://lore.kernel.org/all/CAODzB9roW_ObEa8K8kowbfQ4bL3w4R78v2b_yBU4BQL4bpXrWw@mail.gmail.com/
this commit is not backported to any of the stable kernels (other than 6.15.y)
I have already sent an email for 6.12.y: https://lore.kernel.org/stable/20250727095111.527745-1-duttaditya18@gmail.com/
I will be sending separate emails for 6.1.y and 5.15.y

 fs/jfs/jfs_imap.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 9a6d504228e7..35f3144d703b 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -3029,14 +3029,23 @@ static void duplicateIXtree(struct super_block *sb, s64 blkno,
  *
  * RETURN VALUES:
  *	0	- success
- *	-ENOMEM	- insufficient memory
+ *	-EINVAL	- unexpected inode type
  */
 static int copy_from_dinode(struct dinode * dip, struct inode *ip)
 {
 	struct jfs_inode_info *jfs_ip = JFS_IP(ip);
 	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
+	int fileset = le32_to_cpu(dip->di_fileset);
+
+	switch (fileset) {
+	case AGGR_RESERVED_I: case AGGREGATE_I: case BMAP_I:
+	case LOG_I: case BADBLOCK_I: case FILESYSTEM_I:
+		break;
+	default:
+		return -EINVAL;
+	}
 
-	jfs_ip->fileset = le32_to_cpu(dip->di_fileset);
+	jfs_ip->fileset = fileset;
 	jfs_ip->mode2 = le32_to_cpu(dip->di_mode);
 	jfs_set_inode_flags(ip);
 
-- 
2.34.1