bisecting fixing commit since 13d2ce42de8cb98ff952f8de6307f896203854c2 building syzkaller on 80910769fd1f04ef3263915865ffec0da1d7a421 testing commit 13d2ce42de8cb98ff952f8de6307f896203854c2 with gcc (GCC) 8.1.0 kernel signature: 9c8c15715a3b51675209a6c41b58dc4a210f17105c1d9555683413c2f95ab964 run #0: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #1: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #2: crashed: KASAN: use-after-free Read in squashfs_export_iget run #3: crashed: KASAN: use-after-free Read in squashfs_export_iget run #4: crashed: KASAN: use-after-free Read in squashfs_export_iget run #5: crashed: KASAN: use-after-free Read in squashfs_export_iget run #6: crashed: KASAN: use-after-free Read in squashfs_export_iget run #7: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #8: crashed: KASAN: use-after-free Read in squashfs_export_iget run #9: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget testing current HEAD c4ff839de17f38b0ae0f8983b5c5186f8a389238 testing commit c4ff839de17f38b0ae0f8983b5c5186f8a389238 with gcc (GCC) 8.1.0 kernel signature: 6bc92bb410a221e2a0d068a108e3c81a36198fc087a92cef84cab22712777555 run #0: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #1: crashed: KASAN: use-after-free Read in squashfs_export_iget run #2: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #3: crashed: KASAN: use-after-free Read in squashfs_export_iget run #4: crashed: KASAN: use-after-free Read in squashfs_export_iget run #5: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #6: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #7: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #8: crashed: KASAN: slab-out-of-bounds Read in squashfs_export_iget run #9: crashed: KASAN: use-after-free Read in squashfs_export_iget revisions tested: 2, total time: 23m35.439845744s (build: 16m53.470081728s, test: 5m51.703385874s) the crash still happens on HEAD commit msg: Linux 4.19.171 crash: KASAN: use-after-free Read in squashfs_export_iget IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50 IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready ================================================================== BUG: KASAN: use-after-free in squashfs_inode_lookup fs/squashfs/export.c:57 [inline] BUG: KASAN: use-after-free in squashfs_export_iget+0x22a/0x260 fs/squashfs/export.c:82 Read of size 8 at addr ffff888098414d90 by task syz-executor.3/9853 CPU: 1 PID: 9853 Comm: syz-executor.3 Not tainted 4.19.171-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+0x17c/0x226 lib/dump_stack.c:118 print_address_description.cold.6+0x9/0x211 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 squashfs_inode_lookup fs/squashfs/export.c:57 [inline] squashfs_export_iget+0x22a/0x260 fs/squashfs/export.c:82 squashfs_fh_to_dentry+0x49/0x70 fs/squashfs/export.c:97 exportfs_decode_fh+0x119/0x670 fs/exportfs/expfs.c:433 do_handle_to_path fs/fhandle.c:152 [inline] handle_to_path fs/fhandle.c:207 [inline] do_handle_open+0x26c/0x5d0 fs/fhandle.c:223 IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 __do_sys_open_by_handle_at fs/fhandle.c:265 [inline] __se_sys_open_by_handle_at fs/fhandle.c:256 [inline] __x64_sys_open_by_handle_at+0x71/0xb0 fs/fhandle.c:256 wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45e299 Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready RSP: 002b:00007ff17cb37c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000130 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045e299 RDX: 0000000000000000 RSI: 00000000200003c0 RDI: 0000000000000003 RBP: 000000000119bfc0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c R13: 00007ffff82272ff R14: 00007ff17cb389c0 R15: 000000000119bf8c ieee80211 phy8: Selected rate control algorithm 'minstrel_ht' Allocated by task 9837: IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:553 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:538 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x390 mm/slab.c:3559 getname_flags+0xb8/0x510 fs/namei.c:140 getname+0xd/0x10 fs/namei.c:211 do_sys_open+0x14c/0x350 fs/open.c:1079 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9837: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x13c/0x220 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 putname+0xa8/0xe0 fs/namei.c:261 do_sys_open+0x16e/0x350 fs/open.c:1094 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880984142c0 which belongs to the cache names_cache of size 4096 The buggy address is located 2768 bytes inside of 4096-byte region [ffff8880984142c0, ffff8880984152c0) The buggy address belongs to the page: page:ffffea0002610500 count:1 mapcount:0 mapping:ffff88823b845200 index:0x0 compound_mapcount: 0 flags: 0xfff00000008100(slab|head) raw: 00fff00000008100 ffffea0002621188 ffffea0002610588 ffff88823b845200 raw: 0000000000000000 ffff8880984142c0 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888098414c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888098414d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888098414d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 ffff888098414e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888098414e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb 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