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Wed, 11 Feb 2026 01:21:59 -0800 (PST) Date: Wed, 11 Feb 2026 01:21:59 -0800 In-Reply-To: <20260210222310.357755-1-ethan.ferguson@zetier.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <698c4a37.050a0220.2eeac1.0097.GAE@google.com> Subject: [syzbot ci] Re: fat: Add FS_IOC_GETFSLABEL / FS_IOC_SETFSLABEL ioctls From: syzbot ci To: ethan.ferguson@zetier.com, hirofumi@mail.parknet.co.jp, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot ci has tested the following series [v1] fat: Add FS_IOC_GETFSLABEL / FS_IOC_SETFSLABEL ioctls https://lore.kernel.org/all/20260210222310.357755-1-ethan.ferguson@zetier.com * [PATCH 1/2] fat: Add FS_IOC_GETFSLABEL ioctl * [PATCH 2/2] fat: Add FS_IOC_SETFSLABEL ioctl and found the following issue: WARNING in __brelse Full report is available here: https://ci.syzbot.org/series/2497ea10-8eee-4346-a692-2f79990b4572 *** WARNING in __brelse tree: bpf URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf.git base: 9f2693489ef8558240d9e80bfad103650daed0af arch: amd64 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 config: https://ci.syzbot.org/builds/1d8ee174-a672-4f80-98f2-369e5475eb4f/config C repro: https://ci.syzbot.org/findings/4c8d33e8-6c68-4ab8-ab0c-7be7952f7dcf/c_repro syz repro: https://ci.syzbot.org/findings/4c8d33e8-6c68-4ab8-ab0c-7be7952f7dcf/syz_repro loop0: detected capacity change from 0 to 8192 ------------[ cut here ]------------ VFS: brelse: Trying to free free buffer WARNING: fs/buffer.c:1237 at __brelse+0x6a/0x90 fs/buffer.c:1237, CPU#1: syz.0.17/5957 Modules linked in: CPU: 1 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:__brelse+0x6a/0x90 fs/buffer.c:1237 Code: 75 72 ff 85 ed 74 17 e8 c4 70 72 ff 48 89 df be 04 00 00 00 e8 27 c3 da ff f0 ff 0b eb 11 e8 ad 70 72 ff 48 8d 3d d6 ff a2 0d <67> 48 0f b9 3a 5b 5d c3 cc cc cc cc cc 89 d9 80 e1 07 80 c1 03 38 RSP: 0018:ffffc90003f07b48 EFLAGS: 00010293 RAX: ffffffff825206a3 RBX: ffff8881b6fd5d10 RCX: ffff888177b557c0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8ff50680 RBP: 0000000000000000 R08: ffff8881b6fd5d13 R09: 1ffff11036dfaba2 R10: dffffc0000000000 R11: ffffed1036dfaba3 R12: ffffc90003f07b78 R13: ffffc90003f07b70 R14: ffff8881bba28db0 R15: ffffc90003f07b68 FS: 0000555560eae500(0000) GS:ffff8882a96f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000080 CR3: 000000010b660000 CR4: 00000000000006f0 Call Trace: brelse include/linux/buffer_head.h:324 [inline] fat_rename_volume_label_dentry+0x11f/0x1c0 fs/fat/dir.c:1444 fat_ioctl_set_volume_label fs/fat/file.c:174 [inline] fat_generic_ioctl+0x751/0xfe0 fs/fat/file.c:195 fat_dir_ioctl+0x166/0x320 fs/fat/dir.c:816 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fce15b9bf79 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe48117898 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fce15e15fa0 RCX: 00007fce15b9bf79 RDX: 00002000000004c0 RSI: 0000000041009432 RDI: 0000000000000004 RBP: 00007fce15c327e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fce15e15fac R14: 00007fce15e15fa0 R15: 00007fce15e15fa0 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 72 ff jb 0x1 2: 85 ed test %ebp,%ebp 4: 74 17 je 0x1d 6: e8 c4 70 72 ff call 0xff7270cf b: 48 89 df mov %rbx,%rdi e: be 04 00 00 00 mov $0x4,%esi 13: e8 27 c3 da ff call 0xffdac33f 18: f0 ff 0b lock decl (%rbx) 1b: eb 11 jmp 0x2e 1d: e8 ad 70 72 ff call 0xff7270cf 22: 48 8d 3d d6 ff a2 0d lea 0xda2ffd6(%rip),%rdi # 0xda2ffff * 29: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2e: 5b pop %rbx 2f: 5d pop %rbp 30: c3 ret 31: cc int3 32: cc int3 33: cc int3 34: cc int3 35: cc int3 36: 89 d9 mov %ebx,%ecx 38: 80 e1 07 and $0x7,%cl 3b: 80 c1 03 add $0x3,%cl 3e: 38 .byte 0x38 *** If these findings have caused you to resend the series or submit a separate fix, please add the following tag to your commit message: Tested-by: syzbot@syzkaller.appspotmail.com --- This report is generated by a bot. It may contain errors. syzbot ci engineers can be reached at syzkaller@googlegroups.com.