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: 0 UID: 0 PID: 25966 Comm: syz.1.3638 Tainted: G     U       L      syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:zcomp_stream_get+0x26/0xa0 drivers/block/zram/zcomp.c:113
Code: 90 90 90 90 0f 1f 40 d6 41 55 49 bd 00 00 00 00 00 fc ff df 41 54 49 89 fc 55 49 c1 ec 03 48 89 fd 53 4d 01 ec e8 4a 80 cd fb <41> 80 3c 24 00 65 48 8b 1d 65 75 d2 0d 75 4f 48 03 5d 00 31 f6 48
RSP: 0018:ffffc900064a7480 EFLAGS: 00010283
RAX: 0000000000000579 RBX: dffffc0000000000 RCX: ffffc900067d9000
RDX: 0000000000080000 RSI: ffffffff863a7ab6 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea00004d0000
FS:  00007f83ffa016c0(0000) GS:ffff888124351000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30efdff8 CR3: 00000000207c2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 zram_write_page drivers/block/zram/zram_drv.c:2268 [inline]
 zram_bvec_write drivers/block/zram/zram_drv.c:2341 [inline]
 zram_bio_write drivers/block/zram/zram_drv.c:2773 [inline]
 zram_submit_bio+0xd83/0x1f60 drivers/block/zram/zram_drv.c:2802
 __submit_bio+0x419/0x6c0 block/blk-core.c:644
 __submit_bio_noacct block/blk-core.c:690 [inline]
 submit_bio_noacct_nocheck+0x74f/0xc10 block/blk-core.c:755
 submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884
 submit_bio_wait+0x110/0x250 block/bio.c:1508
 __blkdev_direct_IO_simple+0x485/0x880 block/fops.c:99
 blkdev_direct_IO+0xc76/0x1fb0 block/fops.c:431
 blkdev_direct_write block/fops.c:723 [inline]
 blkdev_write_iter+0x703/0xd70 block/fops.c:791
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1070 fs/read_write.c:688
 ksys_write+0x12a/0x250 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f83feb9c629
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:00007f83ffa01028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f83fee15fa0 RCX: 00007f83feb9c629
RDX: 000000100000a3d9 RSI: 0000200000000400 RDI: 0000000000000006
RBP: 00007f83fec32b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f83fee16038 R14: 00007f83fee15fa0 R15: 00007fff6f2955b8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:zcomp_stream_get+0x26/0xa0 drivers/block/zram/zcomp.c:113
Code: 90 90 90 90 0f 1f 40 d6 41 55 49 bd 00 00 00 00 00 fc ff df 41 54 49 89 fc 55 49 c1 ec 03 48 89 fd 53 4d 01 ec e8 4a 80 cd fb <41> 80 3c 24 00 65 48 8b 1d 65 75 d2 0d 75 4f 48 03 5d 00 31 f6 48
RSP: 0018:ffffc900064a7480 EFLAGS: 00010283
RAX: 0000000000000579 RBX: dffffc0000000000 RCX: ffffc900067d9000
RDX: 0000000000080000 RSI: ffffffff863a7ab6 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea00004d0000
FS:  00007f83ffa016c0(0000) GS:ffff888124351000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30fdaff8 CR3: 00000000207c2000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	90                   	nop
   2:	90                   	nop
   3:	90                   	nop
   4:	0f 1f 40 d6          	nopl   -0x2a(%rax)
   8:	41 55                	push   %r13
   a:	49 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%r13
  11:	fc ff df
  14:	41 54                	push   %r12
  16:	49 89 fc             	mov    %rdi,%r12
  19:	55                   	push   %rbp
  1a:	49 c1 ec 03          	shr    $0x3,%r12
  1e:	48 89 fd             	mov    %rdi,%rbp
  21:	53                   	push   %rbx
  22:	4d 01 ec             	add    %r13,%r12
  25:	e8 4a 80 cd fb       	call   0xfbcd8074
* 2a:	41 80 3c 24 00       	cmpb   $0x0,(%r12) <-- trapping instruction
  2f:	65 48 8b 1d 65 75 d2 	mov    %gs:0xdd27565(%rip),%rbx        # 0xdd2759c
  36:	0d
  37:	75 4f                	jne    0x88
  39:	48 03 5d 00          	add    0x0(%rbp),%rbx
  3d:	31 f6                	xor    %esi,%esi
  3f:	48                   	rex.W