FAT-fs (loop3): error, invalid access to FAT (entry 0x0fffff00) FAT-fs (loop3): Filesystem has been set read-only Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 UID: 0 PID: 6088 Comm: syz.3.40 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:bio_get_first_bvec block/blk-merge.c:22 [inline] RIP: 0010:bio_get_last_bvec block/blk-merge.c:30 [inline] RIP: 0010:bio_seg_gap+0x1c6/0x7d0 block/blk-merge.c:743 Code: fd 48 ba 00 00 00 00 00 fc ff df 49 8b 06 48 89 5c 24 20 49 89 de 49 c1 e6 04 48 89 44 24 08 4a 8d 2c 30 48 89 e8 48 c1 e8 03 <80> 3c 10 00 74 12 48 89 ef e8 7c 04 b9 fd 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc900047f69a0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000080000 RDX: dffffc0000000000 RSI: 0000000000005112 RDI: ffff8880339ba170 RBP: 0000000000000000 R08: ffff888024e775e7 R09: 1ffff110049ceebc R10: dffffc0000000000 R11: ffffed10049ceebd R12: 0000000000000c00 R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880339ba140 FS: 00007f5e8f60d6c0(0000) GS:ffff888125ecc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3b3513 CR3: 0000000078fae000 CR4: 00000000003526f0 Call Trace: bio_attempt_back_merge+0x4ae/0x930 block/blk-merge.c:940 blk_attempt_plug_merge+0x145/0x1d0 block/blk-merge.c:1073 blk_mq_attempt_bio_merge block/blk-mq.c:3022 [inline] blk_mq_submit_bio+0x1aad/0x26e0 block/blk-mq.c:3186 __submit_bio+0x207/0x5a0 block/blk-core.c:637 __submit_bio_noacct_mq block/blk-core.c:724 [inline] submit_bio_noacct_nocheck+0x2eb/0xa50 block/blk-core.c:755 submit_bio_wait+0x104/0x200 block/bio.c:1389 blkdev_issue_discard+0x113/0x1b0 block/blk-lib.c:95 sb_issue_discard include/linux/blkdev.h:1280 [inline] fat_free_clusters+0x405/0xb80 fs/fat/fatent.c:588 fat_add_cluster fs/fat/inode.c:115 [inline] __fat_get_block fs/fat/inode.c:155 [inline] fat_get_block+0x699/0xa70 fs/fat/inode.c:190 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145 block_write_begin fs/buffer.c:2256 [inline] cont_write_begin+0x78c/0xb50 fs/buffer.c:2594 fat_write_begin+0x7a/0x150 fs/fat/inode.c:230 cont_expand_zero fs/buffer.c:2522 [inline] cont_write_begin+0x2fd/0xb50 fs/buffer.c:2584 fat_write_begin+0x7a/0x150 fs/fat/inode.c:230 generic_perform_write+0x2c5/0x900 mm/filemap.c:4313 generic_file_write_iter+0x117/0x550 mm/filemap.c:4456 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_pwrite64 fs/read_write.c:793 [inline] __do_sys_pwrite64 fs/read_write.c:801 [inline] __se_sys_pwrite64 fs/read_write.c:798 [inline] __x64_sys_pwrite64+0x193/0x220 fs/read_write.c:798 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5e8e78f6c9 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:00007f5e8f60d038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 RAX: ffffffffffffffda RBX: 00007f5e8e9e5fa0 RCX: 00007f5e8e78f6c9 RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000004 RBP: 00007f5e8e811f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5e8e9e6038 R14: 00007f5e8e9e5fa0 R15: 00007ffced0a0368 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:bio_get_first_bvec block/blk-merge.c:22 [inline] RIP: 0010:bio_get_last_bvec block/blk-merge.c:30 [inline] RIP: 0010:bio_seg_gap+0x1c6/0x7d0 block/blk-merge.c:743 Code: fd 48 ba 00 00 00 00 00 fc ff df 49 8b 06 48 89 5c 24 20 49 89 de 49 c1 e6 04 48 89 44 24 08 4a 8d 2c 30 48 89 e8 48 c1 e8 03 <80> 3c 10 00 74 12 48 89 ef e8 7c 04 b9 fd 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc900047f69a0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000080000 RDX: dffffc0000000000 RSI: 0000000000005112 RDI: ffff8880339ba170 RBP: 0000000000000000 R08: ffff888024e775e7 R09: 1ffff110049ceebc R10: dffffc0000000000 R11: ffffed10049ceebd R12: 0000000000000c00 R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880339ba140 FS: 00007f5e8f60d6c0(0000) GS:ffff888125ecc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd050bb3ad8 CR3: 0000000078fae000 CR4: 00000000003526f0 ---------------- Code disassembly (best guess): 0: fd std 1: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx 8: fc ff df b: 49 8b 06 mov (%r14),%rax e: 48 89 5c 24 20 mov %rbx,0x20(%rsp) 13: 49 89 de mov %rbx,%r14 16: 49 c1 e6 04 shl $0x4,%r14 1a: 48 89 44 24 08 mov %rax,0x8(%rsp) 1f: 4a 8d 2c 30 lea (%rax,%r14,1),%rbp 23: 48 89 e8 mov %rbp,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 80 3c 10 00 cmpb $0x0,(%rax,%rdx,1) <-- trapping instruction 2e: 74 12 je 0x42 30: 48 89 ef mov %rbp,%rdi 33: e8 7c 04 b9 fd call 0xfdb904b4 38: 48 rex.W 39: ba 00 00 00 00 mov $0x0,%edx 3e: 00 fc add %bh,%ah