[syzbot] [ntfs3?] WARNING in ni_rename

[syzbot] [ntfs3?] WARNING in ni_rename

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    1b152eeca84a Add linux-next specific files for 20250625
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1409df0c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a3d8d413c6928dae
dashboard link: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1683770c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1183770c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4fe40968b29a/disk-1b152eec.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/edf810403580/vmlinux-1b152eec.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0b63be52ad9a/bzImage-1b152eec.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/3256aebc06d8/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: fs/ntfs3/frecord.c:3030 at ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029, CPU#0: syz-executor359/5838
Modules linked in:
CPU: 0 UID: 0 PID: 5838 Comm: syz-executor359 Not tainted 6.16.0-rc3-next-20250625-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029
Code: 8b 05 36 32 9a 0f 48 3b 44 24 10 75 22 44 89 e0 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 19 b4 6b 08 cc e8 73 fe b9 fe 90 <0f> 0b 90 eb c5 e8 e8 d9 68 08 0f 1f 84 00 00 00 00 00 90 90 90 90
RSP: 0018:ffffc9000420fab8 EFLAGS: 00010293
RAX: ffffffff8305be0d RBX: 00000000fffffffe RCX: ffff888029afbc00
RDX: 0000000000000000 RSI: 00000000fffffffe RDI: 0000000000000000
RBP: 00000000fffffffe R08: ffffffff8fa18d37 R09: 1ffffffff1f431a6
R10: dffffc0000000000 R11: fffffbfff1f431a7 R12: 0000000000000000
R13: ffff88807c10a200 R14: ffff8880776e8758 R15: ffff888073d566d0
FS:  0000555581b87380(0000) GS:ffff888125c21000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e3bd1067a8 CR3: 0000000072ba4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ntfs_rename+0x6e2/0xb40 fs/ntfs3/namei.c:316
 vfs_rename+0xbda/0xf00 fs/namei.c:5129
 do_renameat2+0x6ce/0xa80 fs/namei.c:5278
 __do_sys_rename fs/namei.c:5325 [inline]
 __se_sys_rename fs/namei.c:5323 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe16d5c28b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc6842518 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007fe16d5c28b9
RDX: 0000000000000000 RSI: 0000200000001040 RDI: 0000200000000280
RBP: 0030656c69662f2e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcc68426f8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot] [ntfs3?] WARNING in ni_rename

[Moonhee Lee]

#syz test

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 1bf2a6593dec..15f3a711ea0a 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -478,6 +478,7 @@ static int indx_find_free(struct ntfs_index *indx,
struct ntfs_inode *ni,
        struct ATTR_LIST_ENTRY *le = NULL;
        const struct INDEX_NAMES *in = &s_index_names[indx->type];
        int err;
+       u64 bm_size;

        b = ni_find_attr(ni, NULL, &le, ATTR_BITMAP, in->name, in->name_len,
                         NULL, NULL);
@@ -488,6 +489,17 @@ static int indx_find_free(struct ntfs_index
*indx, struct ntfs_inode *ni,
        *bitmap = b;
        *bit = MINUS_ONE_T;

+       bm_size = b->non_res ? le64_to_cpu(b->nres.valid_size) :
+                              le32_to_cpu(b->res.data_size);
+
+       /*
+        * Allocated index blocks require $BITMAP to contain at least
+        * one bit for usage tracking. A zero-length bitmap in this
+        * case indicates a malformed on-disk structure and cannot be used.
+        */
+       if (unlikely(bm_size == 0 && indx->alloc_run.count))
+               return -EINVAL;
+
        if (!b->non_res) {
                u32 nbits = 8 * le32_to_cpu(b->res.data_size);
                size_t pos = find_next_zero_bit_le(resident_data(b), nbits, 0);

Re: [syzbot] [ntfs3?] WARNING in ni_rename

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in ni_rename

loop0: detected capacity change from 0 to 4096
------------[ cut here ]------------
WARNING: fs/ntfs3/frecord.c:3030 at ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029, CPU#1: syz.0.16/6620
Modules linked in:
CPU: 1 UID: 0 PID: 6620 Comm: syz.0.16 Not tainted 6.16.0-rc4-next-20250704-syzkaller-07381-g26ffb3d6f02c-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029
Code: 8b 05 b6 5d 9a 0f 48 3b 44 24 10 75 22 44 89 e0 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 d9 a6 6c 08 cc e8 f3 7d b9 fe 90 <0f> 0b 90 eb c5 e8 68 cc 69 08 0f 1f 84 00 00 00 00 00 90 90 90 90
RSP: 0018:ffffc900033e7ab8 EFLAGS: 00010293
RAX: ffffffff8306228d RBX: 00000000fffffffe RCX: ffff888021723c00
RDX: 0000000000000000 RSI: 00000000fffffffe RDI: 0000000000000000
RBP: 00000000fffffffe R08: ffffffff8fa18a37 R09: 1ffffffff1f43146
R10: dffffc0000000000 R11: fffffbfff1f43147 R12: 0000000000000000
R13: ffff88802f30d500 R14: ffff88806d04d0c8 R15: ffff88806d04b368
FS:  00007f1edd33f6c0(0000) GS:ffff888125d18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001060 CR3: 000000007c546000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ntfs_rename+0x6e2/0xb40 fs/ntfs3/namei.c:316
 vfs_rename+0xbd7/0xf00 fs/namei.c:5129
 do_renameat2+0x6ce/0xa80 fs/namei.c:5278
 __do_sys_rename fs/namei.c:5325 [inline]
 __se_sys_rename fs/namei.c:5323 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1edc58e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1edd33f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f1edc7b5fa0 RCX: 00007f1edc58e929
RDX: 0000000000000000 RSI: 0000200000001040 RDI: 0000200000000280
RBP: 00007f1edc610b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1edc7b5fa0 R15: 00007ffcb3616c48
 </TASK>


Tested on:

commit:         26ffb3d6 Add linux-next specific files for 20250704
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16c95582580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=59817f9ef599726c
dashboard link: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=175edf70580000

Re: [syzbot] [ntfs3?] WARNING in ni_rename

[Moon Hee Lee]

#syz test

---
 fs/ntfs3/index.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 1bf2a6593dec..15f3a711ea0a 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -478,6 +478,7 @@ static int indx_find_free(struct ntfs_index *indx,
struct ntfs_inode *ni,
        struct ATTR_LIST_ENTRY *le = NULL;
        const struct INDEX_NAMES *in = &s_index_names[indx->type];
        int err;
+       u64 bm_size;

        b = ni_find_attr(ni, NULL, &le, ATTR_BITMAP, in->name, in->name_len,
                         NULL, NULL);
@@ -488,6 +489,17 @@ static int indx_find_free(struct ntfs_index
*indx, struct ntfs_inode *ni,
        *bitmap = b;
        *bit = MINUS_ONE_T;

+       bm_size = b->non_res ? le64_to_cpu(b->nres.valid_size) :
+                              le32_to_cpu(b->res.data_size);
+
+       /*
+        * Allocated index blocks require $BITMAP to contain at least
+        * one bit for usage tracking. A zero-length bitmap in this
+        * case indicates a malformed on-disk structure and cannot be used.
+        */
+       if (unlikely(bm_size == 0 && indx->alloc_run.count))
+               return -EINVAL;
+
        if (!b->non_res) {
                u32 nbits = 8 * le32_to_cpu(b->res.data_size);
                size_t pos = find_next_zero_bit_le(resident_data(b), nbits, 0);
-- 


On Tue, Jul 8, 2025 at 1:13 AM syzbot
<syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> WARNING in ni_rename
>
> loop0: detected capacity change from 0 to 4096
> ------------[ cut here ]------------
> WARNING: fs/ntfs3/frecord.c:3030 at ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029, CPU#1: syz.0.16/6620
> Modules linked in:
> CPU: 1 UID: 0 PID: 6620 Comm: syz.0.16 Not tainted 6.16.0-rc4-next-20250704-syzkaller-07381-g26ffb3d6f02c-dirty #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> RIP: 0010:ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029
> Code: 8b 05 b6 5d 9a 0f 48 3b 44 24 10 75 22 44 89 e0 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 d9 a6 6c 08 cc e8 f3 7d b9 fe 90 <0f> 0b 90 eb c5 e8 68 cc 69 08 0f 1f 84 00 00 00 00 00 90 90 90 90
> RSP: 0018:ffffc900033e7ab8 EFLAGS: 00010293
> RAX: ffffffff8306228d RBX: 00000000fffffffe RCX: ffff888021723c00
> RDX: 0000000000000000 RSI: 00000000fffffffe RDI: 0000000000000000
> RBP: 00000000fffffffe R08: ffffffff8fa18a37 R09: 1ffffffff1f43146
> R10: dffffc0000000000 R11: fffffbfff1f43147 R12: 0000000000000000
> R13: ffff88802f30d500 R14: ffff88806d04d0c8 R15: ffff88806d04b368
> FS:  00007f1edd33f6c0(0000) GS:ffff888125d18000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000001060 CR3: 000000007c546000 CR4: 00000000003526f0
> Call Trace:
>  <TASK>
>  ntfs_rename+0x6e2/0xb40 fs/ntfs3/namei.c:316
>  vfs_rename+0xbd7/0xf00 fs/namei.c:5129
>  do_renameat2+0x6ce/0xa80 fs/namei.c:5278
>  __do_sys_rename fs/namei.c:5325 [inline]
>  __se_sys_rename fs/namei.c:5323 [inline]
>  __x64_sys_rename+0x82/0x90 fs/namei.c:5323
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f1edc58e929
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f1edd33f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
> RAX: ffffffffffffffda RBX: 00007f1edc7b5fa0 RCX: 00007f1edc58e929
> RDX: 0000000000000000 RSI: 0000200000001040 RDI: 0000200000000280
> RBP: 00007f1edc610b39 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 00007f1edc7b5fa0 R15: 00007ffcb3616c48
>  </TASK>
>
>
> Tested on:
>
> commit:         26ffb3d6 Add linux-next specific files for 20250704
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=16c95582580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=59817f9ef599726c
> dashboard link: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
> compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
> patch:          https://syzkaller.appspot.com/x/patch.diff?x=175edf70580000
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/syzkaller-bugs/686cd312.a00a0220.338033.0009.GAE%40google.com.

Re: [syzbot] [ntfs3?] WARNING in ni_rename

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in ni_rename

loop0: detected capacity change from 0 to 4096
------------[ cut here ]------------
WARNING: fs/ntfs3/frecord.c:3030 at ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029, CPU#1: syz.0.16/6603
Modules linked in:
CPU: 1 UID: 0 PID: 6603 Comm: syz.0.16 Not tainted 6.16.0-rc4-next-20250704-syzkaller-07381-g26ffb3d6f02c-dirty #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ni_rename+0xee/0x100 fs/ntfs3/frecord.c:3029
Code: 8b 05 b6 5d 9a 0f 48 3b 44 24 10 75 22 44 89 e0 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 d9 a6 6c 08 cc e8 f3 7d b9 fe 90 <0f> 0b 90 eb c5 e8 68 cc 69 08 0f 1f 84 00 00 00 00 00 90 90 90 90
RSP: 0018:ffffc90003007ab8 EFLAGS: 00010293
RAX: ffffffff8306228d RBX: 00000000fffffffe RCX: ffff8880274e5a00
RDX: 0000000000000000 RSI: 00000000fffffffe RDI: 0000000000000000
RBP: 00000000fffffffe R08: ffffffff8fa18a37 R09: 1ffffffff1f43146
R10: dffffc0000000000 R11: fffffbfff1f43147 R12: 0000000000000000
R13: ffff88802d5e3300 R14: ffff88805b6e8758 R15: ffff88805b6e66d0
FS:  00007f5d3eea16c0(0000) GS:ffff888125d18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001060 CR3: 0000000032258000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ntfs_rename+0x6e2/0xb40 fs/ntfs3/namei.c:316
 vfs_rename+0xbd7/0xf00 fs/namei.c:5129
 do_renameat2+0x6ce/0xa80 fs/namei.c:5278
 __do_sys_rename fs/namei.c:5325 [inline]
 __se_sys_rename fs/namei.c:5323 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5d3df8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5d3eea1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f5d3e1b5fa0 RCX: 00007f5d3df8e929
RDX: 0000000000000000 RSI: 0000200000001040 RDI: 0000200000000280
RBP: 00007f5d3e010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5d3e1b5fa0 R15: 00007ffe542eb158
 </TASK>


Tested on:

commit:         26ffb3d6 Add linux-next specific files for 20250704
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1484abd4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=59817f9ef599726c
dashboard link: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16ecf28c580000

[syzbot] [ntfs3?] WARNING in ni_rename

[Moon Hee Lee]

[-- Attachment #1: Type: text/plain, Size: 10 bytes --]

#syz test

[-- Attachment #2: 0001-ntfs3-reject-zero-length-BITMAP-when-index-blocks-ar.patch --]
[-- Type: text/x-patch, Size: 1655 bytes --]

From a7e94ad4959e46acf3861fa0c725a2d0c3373ebb Mon Sep 17 00:00:00 2001
From: Moon Hee Lee <moonhee.lee.ca@gmail.com>
Date: Tue, 8 Jul 2025 01:17:13 -0700
Subject: [PATCH] ntfs3: reject zero-length $BITMAP when index blocks are
 allocated

A non-empty index allocation requires at least one bit in $BITMAP
to track usage. Reject malformed on-disk structures with zero-length
bitmaps and allocated index blocks.

Signed-off-by: Moon Hee Lee <moonhee.lee.ca@gmail.com>
---
 fs/ntfs3/index.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 1bf2a6593dec..15f3a711ea0a 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -478,6 +478,7 @@ static int indx_find_free(struct ntfs_index *indx, struct ntfs_inode *ni,
 	struct ATTR_LIST_ENTRY *le = NULL;
 	const struct INDEX_NAMES *in = &s_index_names[indx->type];
 	int err;
+	u64 bm_size;
 
 	b = ni_find_attr(ni, NULL, &le, ATTR_BITMAP, in->name, in->name_len,
 			 NULL, NULL);
@@ -488,6 +489,17 @@ static int indx_find_free(struct ntfs_index *indx, struct ntfs_inode *ni,
 	*bitmap = b;
 	*bit = MINUS_ONE_T;
 
+	bm_size = b->non_res ? le64_to_cpu(b->nres.valid_size) :
+			       le32_to_cpu(b->res.data_size);
+
+	/*
+	 * Allocated index blocks require $BITMAP to contain at least
+	 * one bit for usage tracking. A zero-length bitmap in this
+	 * case indicates a malformed on-disk structure and cannot be used.
+	 */
+	if (unlikely(bm_size == 0 && indx->alloc_run.count))
+		return -EINVAL;
+
 	if (!b->non_res) {
 		u32 nbits = 8 * le32_to_cpu(b->res.data_size);
 		size_t pos = find_next_zero_bit_le(resident_data(b), nbits, 0);
-- 
2.43.0

Re: [syzbot] [ntfs3?] WARNING in ni_rename

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com
Tested-by: syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com

Tested on:

commit:         26ffb3d6 Add linux-next specific files for 20250704
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13a14a8c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=59817f9ef599726c
dashboard link: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12a9df70580000

Note: testing is done by a robot and is best-effort only.

[syzbot] [ntfs3?] WARNING in ni_rename

[Moon Hee Lee]

[-- Attachment #1: Type: text/plain, Size: 10 bytes --]

#syz test

[-- Attachment #2: 0001-ntfs3-validate-BITMAP-size-when-index-blocks-are-pre.patch --]
[-- Type: text/x-patch, Size: 1098 bytes --]

From 7fa1f4b399c2d47d1ab301c2662f6a60c2098c45 Mon Sep 17 00:00:00 2001
From: Moon Hee Lee <moonhee.lee.ca@gmail.com>
Date: Tue, 8 Jul 2025 14:39:43 -0700
Subject: [PATCH] ntfs3: validate $BITMAP size when index blocks are present

Reject directories with allocated index blocks but zero-length $BITMAP,
as this indicates an inconsistent on-disk structure.

Signed-off-by: Moon Hee Lee <moonhee.lee.ca@gmail.com>
---
 fs/ntfs3/index.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 1bf2a6593dec..6d1bf890929d 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -1508,6 +1508,16 @@ static int indx_add_allocate(struct ntfs_index *indx, struct ntfs_inode *ni,
 			bmp_size = bmp_size_v = le32_to_cpu(bmp->res.data_size);
 		}
 
+		/*
+		 * Index blocks exist, but $BITMAP has zero valid bits.
+		 * This implies an on-disk corruption and must be rejected.
+		 */
+		if (in->name == I30_NAME &&
+		    unlikely(bmp_size_v == 0 && indx->alloc_run.count)) {
+			err = -EINVAL;
+			goto out1;
+		}
+
 		bit = bmp_size << 3;
 	}
 
-- 
2.43.0

Re: [syzbot] [ntfs3?] WARNING in ni_rename

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com
Tested-by: syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com

Tested on:

commit:         58ba80c4 Add linux-next specific files for 20250708
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=122fd582580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bac86b8500d50c98
dashboard link: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10dc6bd4580000

Note: testing is done by a robot and is best-effort only.