[v5.15] Internal error in fat_generic_ioctl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c79648372d02 Linux 5.15.189
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14547042580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=f761bba47ccbb8d8e72e
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ab49562317a/disk-c7964837.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e847ec1e38d3/vmlinux-c7964837.xz
kernel image: https://storage.googleapis.com/syzbot-assets/263158c6371c/Image-c7964837.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f761bb...@syzkaller.appspotmail.com

loop1: detected capacity change from 0 to 128
Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4445 Comm: syz.1.75 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 42400405 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : fat_generic_ioctl+0x694/0xeac fs/fat/file.c:163
lr : fat_ioctl_get_attributes fs/fat/file.c:29 [inline]
lr : fat_generic_ioctl+0x670/0xeac fs/fat/file.c:163
sp : ffff80001fea7ba0
x29: ffff80001fea7cd0 x28: ffff0000c54c9b40 x27: 0000000000000002
x26: dfff800000000000 x25: ffff700003fd4f78 x24: 0000000000008140
x23: 0000000000000003 x22: 0000000000000092 x21: 0000000000400140
x20: 0000000000000000 x19: 0000000000000001 x18: 0000000000000000
x17: ffff800016d04000 x16: ffff800008e4664c x15: ffff8000167e4500
x14: ffff0000c54ca540 x13: 1ffff0000282e06b x12: 0000000000000000
x11: 0000000000000003 x10: 0000ffffffffffff x9 : 0000000000000000
x8 : 00000000fffffff2 x7 : ffff800008750ed4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
fat_ioctl_get_attributes fs/fat/file.c:32 [inline]
fat_generic_ioctl+0x694/0xeac fs/fat/file.c:163
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: ea2a013f 9a9f028c d503229f b800098b (93407d00)
---[ end trace 12908e15f75b8900 ]---
----------------
Code disassembly (best guess):
0: ea2a013f bics xzr, x9, x10
4: 9a9f028c csel x12, x20, xzr, eq // eq = none
8: d503229f csdb
c: b800098b sttr w11, [x12]
* 10: 93407d00 sxtw x0, w8 <-- trapping instruction


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: c79648372d02 Linux 5.15.189
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=159529a2580000

kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=f761bba47ccbb8d8e72e
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=176fb434580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=137f19a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ab49562317a/disk-c7964837.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e847ec1e38d3/vmlinux-c7964837.xz
kernel image: https://storage.googleapis.com/syzbot-assets/263158c6371c/Image-c7964837.gz.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/92d4c8815689/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=157f19a2580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f761bb...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 256

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:

CPU: 1 PID: 4209 Comm: syz.0.17 Not tainted 5.15.189-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 42400405 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : fat_generic_ioctl+0x694/0xeac fs/fat/file.c:163
lr : fat_ioctl_get_attributes fs/fat/file.c:29 [inline]
lr : fat_generic_ioctl+0x670/0xeac fs/fat/file.c:163

sp : ffff80001fcf7a80
x29: ffff80001fcf7ba0 x28: ffff0000d5c21b40 x27: 0000000000000010
x26: dfff800000000000 x25: ffff700003f9ef54 x24: 00000000000041c0
x23: 0000000000000010 x22: 0000000000000092 x21: 0000000000400140

x20: 0000000000000000 x19: 0000000000000001 x18: 0000000000000000
x17: ffff800016d04000 x16: ffff800008e4664c x15: ffff8000167e4500

x14: ffff0000d5c22540 x13: 1ffff0000282e06b x12: 0000000000000000
x11: 0000000000000010 x10: 0000ffffffffffff x9 : 0000000000000000

x8 : 00000000fffffff2 x7 : ffff800008750ed4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
fat_ioctl_get_attributes fs/fat/file.c:32 [inline]
fat_generic_ioctl+0x694/0xeac fs/fat/file.c:163

fat_dir_ioctl+0x184/0x36c fs/fat/dir.c:804

vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl fs/ioctl.c:860 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: ea2a013f 9a9f028c d503229f b800098b (93407d00)

---[ end trace 065221c166a169ba ]---

----------------
Code disassembly (best guess):
0: ea2a013f bics xzr, x9, x10
4: 9a9f028c csel x12, x20, xzr, eq // eq = none
8: d503229f csdb
c: b800098b sttr w11, [x12]
* 10: 93407d00 sxtw x0, w8 <-- trapping instruction


---

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