On Wed, Apr 12, 2017 at 5:58 AM, Andrew Zhu Aday <andrew.a...@columbia.edu> wrote: > Hi all, > > Running syzkaller we've found a "slab-out-of-bounds write in strcpy" error. > > Using kernel 4.10-rc7 from www.kernel.org/pub/linux/kernel/v4.x/testing/ > > Unfortunately, I have not been able to generate a reproducible program. > > ================================================================== > BUG: KASAN: slab-out-of-bounds in strcpy+0x30/0x50 lib/string.c:91 at addr > ffff88003b332e96 > Write of size 1 by task syz-executor2/3247 > CPU: 1 PID: 3247 Comm: syz-executor2 Not tainted 4.10.0-rc7 #3 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > 1.7.5-20140531_083030-gandalf 04/01/2014 > Call Trace: > __dump_stack lib/dump_stack.c:15 [inline] > dump_stack+0x95/0xe3 lib/dump_stack.c:51 > kasan_object_err+0x1c/0x70 mm/kasan/report.c:162 > print_address_description mm/kasan/report.c:200 [inline] > kasan_report_error mm/kasan/report.c:289 [inline] > kasan_report.part.1+0x20e/0x4e0 mm/kasan/report.c:311 > kasan_report+0x20/0x30 mm/kasan/report.c:298 > check_memory_region_inline mm/kasan/kasan.c:315 [inline] > __asan_store1+0x4a/0x50 mm/kasan/kasan.c:744 > strcpy+0x30/0x50 lib/string.c:91 > inotify_handle_event+0x148/0x260 fs/notify/inotify/inotify_fsnotify.c:109 > send_to_group fs/notify/fsnotify.c:179 [inline] > fsnotify+0x50b/0xb50 fs/notify/fsnotify.c:275 > __fsnotify_parent+0xeb/0x190 fs/notify/fsnotify.c:112 > fsnotify_parent include/linux/fsnotify.h:25 [inline] > fsnotify_close include/linux/fsnotify.h:240 [inline] > __fput+0xfc/0x380 fs/file_table.c:194 > ____fput+0x15/0x20 fs/file_table.c:244 > task_work_run+0xcb/0x100 kernel/task_work.c:116 > tracehook_notify_resume include/linux/tracehook.h:191 [inline] > exit_to_usermode_loop+0xc5/0xd0 arch/x86/entry/common.c:160 > prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline] > syscall_return_slowpath+0x128/0x130 arch/x86/entry/common.c:259 > entry_SYSCALL_64_fastpath+0xab/0xad > RIP: 0033:0x44e4f9 > RSP: 002b:00007f9fed919b68 EFLAGS: 00000216 ORIG_RAX: 0000000000000003 > RAX: 0000000000000000 RBX: 00000000006f8000 RCX: 000000000044e4f9 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006 > RBP: 0000000000000033 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000216 R12: 0000000000000006 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > Object at ffff88003b332e60, in cache kmalloc-64 size: 64 > Allocated: > PID = 3247 > > [<ffffffff8104ba96>] save_stack_trace+0x16/0x20 > arch/x86/kernel/stacktrace.c:57 > > [<ffffffff81305916>] save_stack+0x46/0xd0 mm/kasan/kasan.c:502 > > [<ffffffff81305b9d>] set_track mm/kasan/kasan.c:514 [inline] > [<ffffffff81305b9d>] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:605 > > [<ffffffff81301da5>] __kmalloc+0x115/0x2d0 mm/slub.c:3737 > > [<ffffffff8139ba74>] kmalloc include/linux/slab.h:495 [inline] > [<ffffffff8139ba74>] inotify_handle_event+0x84/0x260 > fs/notify/inotify/inotify_fsnotify.c:99 > > [<ffffffff81397e4b>] send_to_group fs/notify/fsnotify.c:179 [inline] > [<ffffffff81397e4b>] fsnotify+0x50b/0xb50 fs/notify/fsnotify.c:275 > > [<ffffffff8139857b>] __fsnotify_parent+0xeb/0x190 fs/notify/fsnotify.c:112 > > [<ffffffff813191cc>] fsnotify_parent include/linux/fsnotify.h:25 [inline] > [<ffffffff813191cc>] fsnotify_close include/linux/fsnotify.h:240 [inline] > [<ffffffff813191cc>] __fput+0xfc/0x380 fs/file_table.c:194 > > [<ffffffff813194b5>] ____fput+0x15/0x20 fs/file_table.c:244 > > [<ffffffff810dfdcb>] task_work_run+0xcb/0x100 kernel/task_work.c:116 > > [<ffffffff810025a5>] tracehook_notify_resume include/linux/tracehook.h:191 > [inline] > [<ffffffff810025a5>] exit_to_usermode_loop+0xc5/0xd0 > arch/x86/entry/common.c:160 > > [<ffffffff81003ae8>] prepare_exit_to_usermode arch/x86/entry/common.c:190 > [inline] > [<ffffffff81003ae8>] syscall_return_slowpath+0x128/0x130 > arch/x86/entry/common.c:259 > > [<ffffffff822e48bd>] entry_SYSCALL_64_fastpath+0xab/0xad > Freed: > PID = 29969 > > [<ffffffff8104ba96>] save_stack_trace+0x16/0x20 > arch/x86/kernel/stacktrace.c:57 > > [<ffffffff81305916>] save_stack+0x46/0xd0 mm/kasan/kasan.c:502 > > [<ffffffff81306183>] set_track mm/kasan/kasan.c:514 [inline] > [<ffffffff81306183>] kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:578 > > [<ffffffff81300a84>] slab_free_hook mm/slub.c:1355 [inline] > [<ffffffff81300a84>] slab_free_freelist_hook mm/slub.c:1377 [inline] > [<ffffffff81300a84>] slab_free mm/slub.c:2954 [inline] > [<ffffffff81300a84>] kfree+0xd4/0x2a0 mm/slub.c:3874 > > [<ffffffff81410ba7>] free_rb_tree_fname+0x67/0xa0 fs/ext4/dir.c:402 > > [<ffffffff81410c12>] ext4_htree_free_dir_info fs/ext4/dir.c:424 [inline] > [<ffffffff81410c12>] ext4_release_dir+0x32/0x50 fs/ext4/dir.c:622 > > [<ffffffff81319265>] __fput+0x195/0x380 fs/file_table.c:208 > > [<ffffffff813194b5>] ____fput+0x15/0x20 fs/file_table.c:244 > > [<ffffffff810dfdcb>] task_work_run+0xcb/0x100 kernel/task_work.c:116 > > [<ffffffff810025a5>] tracehook_notify_resume include/linux/tracehook.h:191 > [inline] > [<ffffffff810025a5>] exit_to_usermode_loop+0xc5/0xd0 > arch/x86/entry/common.c:160 > > [<ffffffff81003ae8>] prepare_exit_to_usermode arch/x86/entry/common.c:190 > [inline] > [<ffffffff81003ae8>] syscall_return_slowpath+0x128/0x130 > arch/x86/entry/common.c:259 > > [<ffffffff822e48bd>] entry_SYSCALL_64_fastpath+0xab/0xad > Memory state around the buggy address: > ffff88003b332d80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88003b332e00: fc fc fc fc fc fc fc fc fc fc fc fc 00 00 00 00 >>ffff88003b332e80: 00 00 06 fc fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff88003b332f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88003b332f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fb > ==================================================================
+ inotify_fsnotify.c maintainers The only explanation I have for the report is that file_name has changed in between strlen and strcpy. Is it possible under any circumstances? That would also explain why it is not reproducible.
