syzbot

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 11647 Comm: syz.3.1289 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:zcomp_stream_get+0x33/0xa0 drivers/block/zram/zcomp.c:113
Code: 00 00 00 00 fc ff df 41 54 55 48 89 fd 53 49 89 ec 49 c1 ec 03 4d 01 ec e8 fa 2e cb fb e8 f5 2e cb fb 65 48 8b 1d 15 41 bf 0d <41> 80 3c 24 00 75 4f 48 03 5d 00 31 f6 48 89 df e8 78 45 84 05 48
RSP: 0018:ffffc9000462f490 EFLAGS: 00010287
RAX: 00000000000006f6 RBX: ffff8881249f9000 RCX: ffffc9000d229000
RDX: 0000000000080000 RSI: ffffffff85f32f0b RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000006 R09: 746d2f636f72702f
R10: 0000000000000000 R11: ffff88801f358b30 R12: dffffc0000000000
R13: dffffc0000000000 R14: 746d2f636f72702f R15: ffffea0001bbc6c0
FS:  00007f476b6f46c0(0000) GS:ffff8881249f9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b310d4ff8 CR3: 000000007683c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 zram_write_page drivers/block/zram/zram_drv.c:2124 [inline]
 zram_bvec_write drivers/block/zram/zram_drv.c:2197 [inline]
 zram_bio_write drivers/block/zram/zram_drv.c:2638 [inline]
 zram_submit_bio+0xde2/0x1e10 drivers/block/zram/zram_drv.c:2667
 __submit_bio+0x304/0x690 block/blk-core.c:646
 __submit_bio_noacct block/blk-core.c:692 [inline]
 submit_bio_noacct_nocheck+0x72f/0xbe0 block/blk-core.c:757
 submit_bio_noacct+0x5bd/0x1f40 block/blk-core.c:879
 submit_bio_wait+0x110/0x250 block/bio.c:1391
 __blkdev_direct_IO_simple+0x488/0x860 block/fops.c:99
 blkdev_direct_IO+0xcb8/0x1fe0 block/fops.c:431
 blkdev_direct_write block/fops.c:723 [inline]
 blkdev_write_iter+0x703/0xe00 block/fops.c:791
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x7d3/0x11d0 fs/read_write.c:686
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f476a78f7c9
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:00007f476b6f4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f476a9e5fa0 RCX: 00007f476a78f7c9
RDX: 000000100000a3d9 RSI: 0000200000000400 RDI: 0000000000000009
RBP: 00007f476a813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f476a9e6038 R14: 00007f476a9e5fa0 R15: 00007ffcab5ba798
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:zcomp_stream_get+0x33/0xa0 drivers/block/zram/zcomp.c:113
Code: 00 00 00 00 fc ff df 41 54 55 48 89 fd 53 49 89 ec 49 c1 ec 03 4d 01 ec e8 fa 2e cb fb e8 f5 2e cb fb 65 48 8b 1d 15 41 bf 0d <41> 80 3c 24 00 75 4f 48 03 5d 00 31 f6 48 89 df e8 78 45 84 05 48
RSP: 0018:ffffc9000462f490 EFLAGS: 00010287
RAX: 00000000000006f6 RBX: ffff8881249f9000 RCX: ffffc9000d229000
RDX: 0000000000080000 RSI: ffffffff85f32f0b RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000006 R09: 746d2f636f72702f
R10: 0000000000000000 R11: ffff88801f358b30 R12: dffffc0000000000
R13: dffffc0000000000 R14: 746d2f636f72702f R15: ffffea0001bbc6c0
FS:  00007f476b6f46c0(0000) GS:ffff8881248f9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000001a1000 CR3: 000000007683c000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 6 bytes skipped:
   0:	df 41 54             	filds  0x54(%rcx)
   3:	55                   	push   %rbp
   4:	48 89 fd             	mov    %rdi,%rbp
   7:	53                   	push   %rbx
   8:	49 89 ec             	mov    %rbp,%r12
   b:	49 c1 ec 03          	shr    $0x3,%r12
   f:	4d 01 ec             	add    %r13,%r12
  12:	e8 fa 2e cb fb       	call   0xfbcb2f11
  17:	e8 f5 2e cb fb       	call   0xfbcb2f11
  1c:	65 48 8b 1d 15 41 bf 	mov    %gs:0xdbf4115(%rip),%rbx        # 0xdbf4139
  23:	0d
* 24:	41 80 3c 24 00       	cmpb   $0x0,(%r12) <-- trapping instruction
  29:	75 4f                	jne    0x7a
  2b:	48 03 5d 00          	add    0x0(%rbp),%rbx
  2f:	31 f6                	xor    %esi,%esi
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 78 45 84 05       	call   0x58445b1
  39:	48                   	rex.W