bisecting fixing commit since 8961076ed318dfd22aa357b41589f07bf67e73b6 building syzkaller on 0767f13fbd87c99aea7893eb64199b76be42cd61 testing commit 8961076ed318dfd22aa357b41589f07bf67e73b6 with gcc (GCC) 8.1.0 kernel signature: d79971ee7a2ecdfaacc4572f2e6ef5a47c1d7eed88df8c0d89dc9e10ceba5ee0 run #0: crashed: KASAN: use-after-free Read in squashfs_get_id run #1: crashed: KASAN: use-after-free Read in squashfs_get_id run #2: crashed: KASAN: use-after-free Read in squashfs_get_id run #3: crashed: KASAN: use-after-free Read in squashfs_get_id run #4: crashed: KASAN: use-after-free Read in squashfs_get_id run #5: crashed: KASAN: use-after-free Read in squashfs_get_id run #6: crashed: KASAN: use-after-free Read in squashfs_get_id run #7: crashed: KASAN: slab-out-of-bounds Read in squashfs_get_id run #8: crashed: KASAN: use-after-free Read in squashfs_get_id run #9: crashed: KASAN: use-after-free Read in squashfs_get_id testing current HEAD 2762b48e9611529239da2e68cba908dbbec9805f testing commit 2762b48e9611529239da2e68cba908dbbec9805f with gcc (GCC) 8.1.0 kernel signature: e99b9927a0afc860d8ec8e06b65d24021bcb2d1489b8416e14f151c9069cdcaa run #0: crashed: KASAN: use-after-free Read in squashfs_get_id run #1: crashed: KASAN: use-after-free Read in squashfs_get_id run #2: crashed: KASAN: use-after-free Read in squashfs_get_id run #3: crashed: KASAN: slab-out-of-bounds Read in squashfs_get_id run #4: crashed: KASAN: use-after-free Read in squashfs_get_id run #5: crashed: KASAN: use-after-free Read in squashfs_get_id run #6: crashed: KASAN: slab-out-of-bounds Read in squashfs_get_id run #7: crashed: KASAN: use-after-free Read in squashfs_get_id run #8: crashed: KASAN: use-after-free Read in squashfs_get_id run #9: crashed: KASAN: use-after-free Read in squashfs_get_id revisions tested: 2, total time: 22m24.273387954s (build: 15m58.290131512s, test: 5m55.959530628s) the crash still happens on HEAD commit msg: Linux 4.14.216 crash: KASAN: use-after-free Read in squashfs_get_id wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 IPv6: ADDRCONF(NETDEV_CHANGE): veth1_macvtap: link becomes ready ================================================================== IPv6: ADDRCONF(NETDEV_CHANGE): veth0_macvtap: link becomes ready BUG: KASAN: use-after-free in squashfs_get_id+0x1af/0x1f0 fs/squashfs/id.c:51 Read of size 8 at addr ffff8881f2c31b00 by task syz-executor.2/9121 CPU: 0 PID: 9121 Comm: syz-executor.2 Not tainted 4.14.216-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:409 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 squashfs_get_id+0x1af/0x1f0 fs/squashfs/id.c:51 squashfs_new_inode fs/squashfs/inode.c:64 [inline] squashfs_read_inode+0x1d6/0x1cd0 fs/squashfs/inode.c:133 squashfs_fill_super+0x135d/0x1a20 fs/squashfs/super.c:318 mount_bdev+0x26f/0x330 fs/super.c:1134 squashfs_mount+0x10/0x20 fs/squashfs/super.c:404 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x46090a RSP: 002b:00007f0ca85bea88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f0ca85beb20 RCX: 000000000046090a RDX: 0000000020000000 RSI: 00000000200000c0 RDI: 00007f0ca85beae0 RBP: 00007f0ca85beae0 R08: 00007f0ca85beb20 R09: 0000000020000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000 R13: 00000000200000c0 R14: 0000000020000200 R15: 0000000020010200 Allocated by task 9121: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc+0x15d/0x410 mm/slab.c:3729 kmalloc_array include/linux/slab.h:607 [inline] kcalloc include/linux/slab.h:618 [inline] squashfs_read_data+0x136/0x1200 fs/squashfs/block.c:100 squashfs_read_table+0xec/0x170 fs/squashfs/cache.c:445 squashfs_read_xattr_id_table+0x27/0x1f0 fs/squashfs/xattr_id.c:72 squashfs_fill_super+0xa6c/0x1a20 fs/squashfs/super.c:233 mount_bdev+0x26f/0x330 fs/super.c:1134 squashfs_mount+0x10/0x20 fs/squashfs/super.c:404 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 9121: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 squashfs_read_data+0x85b/0x1200 fs/squashfs/block.c:205 squashfs_read_table+0xec/0x170 fs/squashfs/cache.c:445 squashfs_read_xattr_id_table+0x27/0x1f0 fs/squashfs/xattr_id.c:72 squashfs_fill_super+0xa6c/0x1a20 fs/squashfs/super.c:233 mount_bdev+0x26f/0x330 fs/super.c:1134 squashfs_mount+0x10/0x20 fs/squashfs/super.c:404 mount_fs+0x7f/0x270 fs/super.c:1237 vfs_kern_mount.part.9+0x58/0x3c0 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2549 [inline] do_mount+0x352/0x2af0 fs/namespace.c:2879 SYSC_mount fs/namespace.c:3095 [inline] SyS_mount+0xb1/0xd0 fs/namespace.c:3072 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff8881f2c31b00 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of 32-byte region [ffff8881f2c31b00, ffff8881f2c31b20) The buggy address belongs to the page: page:ffffea0007cb0c40 count:1 mapcount:0 mapping:ffff8881f2c31000 index:0xffff8881f2c31fc1 flags: 0x17ff00000000100(slab) raw: 017ff00000000100 ffff8881f2c31000 ffff8881f2c31fc1 000000010000003f raw: ffffea000771f860 ffff8881f6001248 ffff8881f60001c0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881f2c31a00: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc ffff8881f2c31a80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc >ffff8881f2c31b00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc ^ ffff8881f2c31b80: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc ffff8881f2c31c00: 00 00 fc fc fc fc fc fc 00 00 fc fc fc fc fc fc ==================================================================