Hi, We found a bug in Linux 6.10 using syzkaller. It is possibly a null pointer dereference bug. The bug report is as follows, but unfortunately there is no generated syzkaller reproducer. Bug report: Oops: general protection fault, probably for non-canonical address 0xdffffc000000000f: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f] CPU: 0 PID: 7637 Comm: rs:main Q:Reg Not tainted 6.10.0 #13 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:vma_start_pgoff mm/interval_tree.c:15 [inline] RIP: 0010:avc_start_pgoff mm/interval_tree.c:63 [inline] RIP: 0010:anon_vma_interval_tree_verify+0x5b/0x150 mm/interval_tree.c:108 Code: 00 4d 8b 77 40 4d 89 fd 49 c1 ed 03 43 80 7c 25 00 00 74 08 4c 89 ff e8 c3 bc 1b 00 49 8b 1f 48 83 c3 78 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 a6 bc 1b 00 48 8b 1b 4c 89 f7 48 RSP: 0018:ffffc9000a457810 EFLAGS: 00010206 RAX: 000000000000000f RBX: 0000000000000078 RCX: ffff888014b75a00 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888018bafc80 RBP: ffffc9000a457970 R08: ffff888024fa2de7 R09: 1ffff110049f45bc R10: dffffc0000000000 R11: ffffed10049f45bd R12: dffffc0000000000 R13: 1ffff11003175f88 R14: 0000000000000000 R15: ffff888018bafc40 FS: 00007f7ce5800700(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f40e98fef98 CR3: 000000001d99e000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> validate_mm+0x2c0/0x510 mm/mmap.c:318 vma_merge+0x15af/0x24b0 mm/mmap.c:1038 vma_modify+0xb4/0x340 mm/mmap.c:2494 vma_modify_flags include/linux/mm.h:3352 [inline] mprotect_fixup+0x3dc/0xa60 mm/mprotect.c:637 do_mprotect_pkey+0x87a/0xc50 mm/mprotect.c:820 __do_sys_mprotect mm/mprotect.c:841 [inline] __se_sys_mprotect mm/mprotect.c:838 [inline] __x64_sys_mprotect+0x7c/0x90 mm/mprotect.c:838 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x7e/0x150 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x67/0x6f RIP: 0033:0x7f7ce69451d7 Code: 73 01 c3 48 8b 0d b9 8c 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0a 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 89 8c 0d 00 f7 d8 64 89 01 48 RSP: 002b:00007f7ce57ff558 EFLAGS: 00000206 ORIG_RAX: 000000000000000a RAX: ffffffffffffffda RBX: 00007f7cd4000020 RCX: 00007f7ce69451d7 RDX: 0000000000000003 RSI: 0000000000001000 RDI: 00007f7cd4044000 RBP: 0000000000000110 R08: 00007f7cd4000000 R09: 0000000000044000 R10: 0000000000000130 R11: 0000000000000206 R12: 0000000000000100 R13: 0000000000001000 R14: 00007f7cd4043f00 R15: fffffffffffff000 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:vma_start_pgoff mm/interval_tree.c:15 [inline] RIP: 0010:avc_start_pgoff mm/interval_tree.c:63 [inline] RIP: 0010:anon_vma_interval_tree_verify+0x5b/0x150 mm/interval_tree.c:108 Code: 00 4d 8b 77 40 4d 89 fd 49 c1 ed 03 43 80 7c 25 00 00 74 08 4c 89 ff e8 c3 bc 1b 00 49 8b 1f 48 83 c3 78 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 a6 bc 1b 00 48 8b 1b 4c 89 f7 48 RSP: 0018:ffffc9000a457810 EFLAGS: 00010206 RAX: 000000000000000f RBX: 0000000000000078 RCX: ffff888014b75a00 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888018bafc80 RBP: ffffc9000a457970 R08: ffff888024fa2de7 R09: 1ffff110049f45bc R10: dffffc0000000000 R11: ffffed10049f45bd R12: dffffc0000000000 R13: 1ffff11003175f88 R14: 0000000000000000 R15: ffff888018bafc40 FS: 00007f7ce5800700(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f40e98fef98 CR3: 000000001d99e000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 00 4d 8b add %cl,-0x75(%rbp) 3: 77 40 ja 0x45 5: 4d 89 fd mov %r15,%r13 8: 49 c1 ed 03 shr $0x3,%r13 c: 43 80 7c 25 00 00 cmpb $0x0,0x0(%r13,%r12,1) 12: 74 08 je 0x1c 14: 4c 89 ff mov %r15,%rdi 17: e8 c3 bc 1b 00 call 0x1bbcdf 1c: 49 8b 1f mov (%r15),%rbx 1f: 48 83 c3 78 add $0x78,%rbx 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 48 89 df mov %rbx,%rdi 34: e8 a6 bc 1b 00 call 0x1bbcdf 39: 48 8b 1b mov (%rbx),%rbx 3c: 4c 89 f7 mov %r14,%rdi 3f: 48 rex.W -- Yours sincerely, Xingyu
