bisecting fixing commit since 4938296e03bd227e5020d63d418956fe52baf97c building syzkaller on bc5f1d88c519868f37bd2b5ebca79b33a659c2c9 testing commit 4938296e03bd227e5020d63d418956fe52baf97c compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: eb9db3c02c8a6dabd5ddb102c2186d0bb4e258628e5dff79669cf188d3bac7d3 all runs: crashed: KASAN: stack-out-of-bounds Read in iov_iter_revert testing current HEAD 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: a9653bffbabd898c8bcd7e34748c4255f2b42cb4cd4544d454b37d6d2ad8b724 all runs: crashed: KASAN: stack-out-of-bounds Read in iov_iter_revert revisions tested: 2, total time: 28m39.818049152s (build: 21m28.311815894s, test: 6m34.326662172s) the crash still happens on HEAD commit msg: Linux 4.19.204 crash: KASAN: stack-out-of-bounds Read in iov_iter_revert Bluetooth: hci1: command 0x0419 tx timeout Bluetooth: hci5: command 0x0419 tx timeout Bluetooth: hci4: command 0x0419 tx timeout Bluetooth: hci2: command 0x0419 tx timeout ================================================================== BUG: KASAN: stack-out-of-bounds in iov_iter_revert lib/iov_iter.c:1047 [inline] BUG: KASAN: stack-out-of-bounds in iov_iter_revert+0x8a9/0xa40 lib/iov_iter.c:996 Read of size 8 at addr ffff88808f467cc0 by task syz-executor.2/9881 CPU: 0 PID: 9881 Comm: syz-executor.2 Not tainted 4.19.204-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 mm/kasan/report.c:412 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:396 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 iov_iter_revert lib/iov_iter.c:1047 [inline] iov_iter_revert+0x8a9/0xa40 lib/iov_iter.c:996 generic_file_read_iter+0xedd/0x2150 mm/filemap.c:2369 fuse_file_read_iter+0x175/0x240 fs/fuse/file.c:944 call_read_iter include/linux/fs.h:1815 [inline] new_sync_read fs/read_write.c:406 [inline] __vfs_read+0x440/0x880 fs/read_write.c:418 vfs_read+0xff/0x300 fs/read_write.c:452 ksys_read+0x103/0x260 fs/read_write.c:579 audit: type=1800 audit(1629647677.964:8): pid=9893 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.0" name="/" dev="fuse" ino=1 res=0 __do_sys_read fs/read_write.c:589 [inline] __se_sys_read fs/read_write.c:587 [inline] __x64_sys_read+0x6e/0xb0 fs/read_write.c:587 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4665e9 audit: type=1800 audit(1629647677.994:9): pid=9995 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="syz-executor.2" name="/" dev="fuse" ino=1 res=0 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f640598b188 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665e9 RDX: 000000002000a3a0 RSI: 0000000020008380 RDI: 0000000000000005 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038 R13: 00007ffd632d0e9f R14: 00007f640598b300 R15: 0000000000022000 The buggy address belongs to the page: page:ffffea00023d19c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0xfff00000000000() raw: 00fff00000000000 0000000000000000 ffffffff023d0101 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808f467b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88808f467c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88808f467c80: 00 00 00 00 00 f1 f1 f1 f1 00 00 f2 f2 f2 f2 f2 ^ ffff88808f467d00: f2 00 00 00 00 00 f2 f2 f2 f2 f2 f2 f2 00 00 00 ffff88808f467d80: 00 00 f2 f2 f2 00 00 00 00 00 00 00 00 00 00 00 ================================================================== ---------------- Code disassembly (best guess), 1 bytes skipped: 0: ff c3 inc %ebx 2: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 9: 00 00 00 c: 0f 1f 40 00 nopl 0x0(%rax) 10: 48 89 f8 mov %rdi,%rax 13: 48 89 f7 mov %rsi,%rdi 16: 48 89 d6 mov %rdx,%rsi 19: 48 89 ca mov %rcx,%rdx 1c: 4d 89 c2 mov %r8,%r10 1f: 4d 89 c8 mov %r9,%r8 22: 4c 8b 4c 24 08 mov 0x8(%rsp),%r9 27: 0f 05 syscall * 29: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax <-- trapping instruction 2f: 73 01 jae 0x32 31: c3 retq 32: 48 c7 c1 bc ff ff ff mov $0xffffffffffffffbc,%rcx 39: f7 d8 neg %eax 3b: 64 89 01 mov %eax,%fs:(%rcx) 3e: 48 rex.W