bisecting fixing commit since 555161ee1b7a74e77ca70fd14ed8a5137c8108ac building syzkaller on 2e29b534005e52c57d726201644ea28ba33a9a3d testing commit 555161ee1b7a74e77ca70fd14ed8a5137c8108ac with gcc (GCC) 8.1.0 kernel signature: 8d3a9cc46fc5e3c705206359b3835ec0c064b9826cdc1756a8024a1a899691af run #0: crashed: general protection fault in scatterwalk_copychunks run #1: crashed: general protection fault in scatterwalk_copychunks run #2: crashed: general protection fault in scatterwalk_copychunks run #3: crashed: general protection fault in scatterwalk_copychunks run #4: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks run #5: crashed: general protection fault in scatterwalk_copychunks run #6: crashed: general protection fault in scatterwalk_copychunks run #7: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks run #8: crashed: general protection fault in scatterwalk_copychunks run #9: crashed: general protection fault in scatterwalk_copychunks testing current HEAD 84920cc7fbe10e838689e8e1437dfd18d6e54a2c testing commit 84920cc7fbe10e838689e8e1437dfd18d6e54a2c with gcc (GCC) 8.1.0 kernel signature: b78cb8a639032e4b1f85c4b311338390a0d12f1ac88cefdf925712beeab8764e run #0: crashed: KASAN: use-after-free Read in scatterwalk_copychunks run #1: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks run #2: crashed: general protection fault in scatterwalk_map_and_copy run #3: crashed: general protection fault in scatterwalk_copychunks run #4: crashed: general protection fault in corrupted run #5: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks run #6: crashed: general protection fault in scatterwalk_copychunks run #7: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks run #8: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks run #9: crashed: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks revisions tested: 2, total time: 27m28.671357522s (build: 19m35.663584035s, test: 6m23.911946343s) the crash still happens on HEAD commit msg: Linux 4.19.121 crash: KASAN: slab-out-of-bounds Read in scatterwalk_copychunks RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000075bfc8 R08: 000000011d100000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f36108c36d4 R13: 00000000004c9478 R14: 00000000004dfdd8 R15: 0000000000000005 ================================================================== BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:348 [inline] BUG: KASAN: slab-out-of-bounds in memcpy_dir crypto/scatterwalk.c:28 [inline] BUG: KASAN: slab-out-of-bounds in scatterwalk_copychunks+0x1e1/0x610 crypto/scatterwalk.c:43 Read of size 4096 at addr ffff88809e9df000 by task syz-executor.1/7694 CPU: 1 PID: 7694 Comm: syz-executor.1 Not tainted 4.19.121-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 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 memcpy+0x23/0x50 mm/kasan/kasan.c:302 memcpy include/linux/string.h:348 [inline] memcpy_dir crypto/scatterwalk.c:28 [inline] scatterwalk_copychunks+0x1e1/0x610 crypto/scatterwalk.c:43 scatterwalk_map_and_copy+0x128/0x190 crypto/scatterwalk.c:72 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 gcmaes_encrypt.constprop.15+0x6d6/0xda0 arch/x86/crypto/aesni-intel_glue.c:956 generic_gcmaes_encrypt+0xfd/0x150 arch/x86/crypto/aesni-intel_glue.c:1297 crypto_aead_encrypt include/crypto/aead.h:335 [inline] gcmaes_wrapper_encrypt+0x109/0x180 arch/x86/crypto/aesni-intel_glue.c:1130 crypto_aead_encrypt include/crypto/aead.h:335 [inline] tls_do_encryption net/tls/tls_sw.c:193 [inline] tls_push_record+0x966/0x1720 net/tls/tls_sw.c:228 tls_sw_sendpage+0x458/0xc00 net/tls/tls_sw.c:585 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 inet_sendpage+0x122/0x600 net/ipv4/af_inet.c:815 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 kernel_sendpage+0x60/0xd0 net/socket.c:3378 sock_sendpage+0x6d/0xd0 net/socket.c:847 pipe_to_sendpage+0x212/0x430 fs/splice.c:452 splice_from_pipe_feed fs/splice.c:503 [inline] __splice_from_pipe+0x2cb/0x720 fs/splice.c:627 splice_from_pipe+0xbb/0x120 fs/splice.c:662 generic_splice_sendpage+0x10/0x20 fs/splice.c:833 do_splice_from fs/splice.c:852 [inline] do_splice+0x4fd/0x12d0 fs/splice.c:1154 __do_sys_splice fs/splice.c:1428 [inline] __se_sys_splice fs/splice.c:1408 [inline] __x64_sys_splice+0x248/0x300 fs/splice.c:1408 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459a29 Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f9757c54c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 00007f9757c54c90 RCX: 0000000000459a29 RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 000000011d100000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9757c556d4 R13: 00000000004c9478 R14: 00000000004dfdd8 R15: 0000000000000005 Allocated by task 21: 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 shmem_alloc_inode+0x15/0x30 mm/shmem.c:3596 alloc_inode+0x56/0x150 fs/inode.c:211 new_inode_pseudo+0xc/0xd0 fs/inode.c:911 new_inode+0x14/0x30 fs/inode.c:940 shmem_get_inode+0x67/0x740 mm/shmem.c:2193 shmem_mknod+0x49/0x1a0 mm/shmem.c:2830 vfs_mknod+0x3ba/0x660 fs/namei.c:3721 handle_create+0x19e/0x4d0 drivers/base/devtmpfs.c:211 handle drivers/base/devtmpfs.c:374 [inline] devtmpfsd+0x1ed/0x490 drivers/base/devtmpfs.c:400 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Freed by task 0: (stack is not available) The buggy address belongs to the object at ffff88809e9df000 which belongs to the cache shmem_inode_cache of size 1200 The buggy address is located 0 bytes inside of 1200-byte region [ffff88809e9df000, ffff88809e9df4b0) The buggy address belongs to the page: page:ffffea00027a77c0 count:1 mapcount:0 mapping:ffff8880aa2bda80 index:0xffff88809e9dfffd flags: 0x1fffc0000000100(slab) raw: 01fffc0000000100 ffffea00027a7708 ffffea0002798a48 ffff8880aa2bda80 raw: ffff88809e9dfffd ffff88809e9df000 0000000100000003 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809e9df380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88809e9df400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88809e9df480: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc ^ ffff88809e9df500: fc fc fc fc fc fc 00 00 00 00 00 00 00 00 00 00 ffff88809e9df580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================