bisecting fixing commit since c3038e718a19fc596f7b1baba0f83d5146dc7784 building syzkaller on 04ca72cd45348daab9d896bbec8ea4c2d13455ac testing commit c3038e718a19fc596f7b1baba0f83d5146dc7784 with gcc (GCC) 8.1.0 kernel signature: 5b2942fb8ea1dd60fd0da218924773ad2dff16d8 run #0: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #1: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find run #2: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #3: crashed: WARNING in bpf_prog_kallsyms_find run #4: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #5: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #6: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #7: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find run #8: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #9: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find testing current HEAD 312017a460d5ea31d646e7148e400e13db799ddc testing commit 312017a460d5ea31d646e7148e400e13db799ddc with gcc (GCC) 8.1.0 kernel signature: 89a983c5f872e21dc4c491d2902f5fe57e560dc5 run #0: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #1: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #2: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find run #3: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #4: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find run #5: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #6: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find run #7: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find run #8: crashed: BUG: unable to handle kernel paging request in bpf_prog_kallsyms_find run #9: crashed: KASAN: use-after-free Read in bpf_prog_kallsyms_find revisions tested: 2, total time: 25m58.167325718s (build: 16m51.105630306s, test: 8m37.795964918s) the crash still happens on HEAD commit msg: Linux 4.19.89 crash: KASAN: use-after-free Read in bpf_prog_kallsyms_find ================================================================== BUG: KASAN: use-after-free in bpf_tree_comp kernel/bpf/core.c:437 [inline] BUG: KASAN: use-after-free in __lt_find include/linux/rbtree_latch.h:115 [inline] BUG: KASAN: use-after-free in latch_tree_find include/linux/rbtree_latch.h:208 [inline] BUG: KASAN: use-after-free in bpf_prog_kallsyms_find+0x1d1/0x2e0 kernel/bpf/core.c:511 Read of size 8 at addr ffff888097087280 by task syz-executor.3/22570 CPU: 0 PID: 22570 Comm: syz-executor.3 Not tainted 4.19.89-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 bpf_tree_comp kernel/bpf/core.c:437 [inline] __lt_find include/linux/rbtree_latch.h:115 [inline] latch_tree_find include/linux/rbtree_latch.h:208 [inline] bpf_prog_kallsyms_find+0x1d1/0x2e0 kernel/bpf/core.c:511 is_bpf_text_address+0x48/0xe0 kernel/bpf/core.c:546 kernel_text_address+0x79/0xf0 kernel/extable.c:152 __kernel_text_address+0xd/0x40 kernel/extable.c:107 unwind_get_return_address+0x61/0xa0 arch/x86/kernel/unwind_frame.c:18 __save_stack_trace+0x9c/0x100 arch/x86/kernel/stacktrace.c:45 save_stack_trace+0x1a/0x20 arch/x86/kernel/stacktrace.c:60 save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3559 getname_flags+0xb8/0x520 fs/namei.c:140 getname fs/namei.c:211 [inline] do_symlinkat+0x80/0x1e0 fs/namei.c:4142 __do_sys_symlink fs/namei.c:4172 [inline] __se_sys_symlink fs/namei.c:4170 [inline] __x64_sys_symlink+0x54/0x80 fs/namei.c:4170 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459c67 Code: 0f 1f 00 b8 5c 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 6d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 4d b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffce571c738 EFLAGS: 00000202 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000459c67 RDX: 00007ffce571c7d3 RSI: 00000000004bf946 RDI: 00007ffce571c7c0 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000013 R10: 0000000000000075 R11: 0000000000000202 R12: 0000000000000001 R13: 00007ffce571c770 R14: 0000000000000000 R15: 00007ffce571c780 Allocated by task 22565: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kmem_cache_alloc_trace+0x152/0x740 mm/slab.c:3625 kmalloc include/linux/slab.h:515 [inline] kzalloc include/linux/slab.h:709 [inline] bpf_prog_alloc+0x1e7/0x270 kernel/bpf/core.c:90 jit_subprogs kernel/bpf/verifier.c:5814 [inline] fixup_call_args kernel/bpf/verifier.c:5933 [inline] bpf_check+0x2fd2/0x585d kernel/bpf/verifier.c:6340 bpf_prog_load+0xa82/0x1030 kernel/bpf/syscall.c:1445 __do_sys_bpf kernel/bpf/syscall.c:2411 [inline] __se_sys_bpf kernel/bpf/syscall.c:2373 [inline] __x64_sys_bpf+0x238/0x380 kernel/bpf/syscall.c:2373 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 5: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kfree+0xcf/0x220 mm/slab.c:3822 bpf_jit_free+0x6f/0x2a0 bpf_prog_free_deferred+0x15d/0x3a0 kernel/bpf/core.c:1809 process_one_work+0x830/0x1670 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 The buggy address belongs to the object at ffff888097087200 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 128 bytes inside of 256-byte region [ffff888097087200, ffff888097087300) The buggy address belongs to the page: page:ffffea00025c21c0 count:1 mapcount:0 mapping:ffff88812c35e7c0 index:0x0 flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffffea000246a948 ffffea0002296ac8 ffff88812c35e7c0 raw: 0000000000000000 ffff8880970870c0 000000010000000c 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888097087180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888097087200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888097087280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888097087300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff888097087380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================