memory leak in prepare

memory leak in prepare_creds
Status: upstream: reported C repro on 2020/08/27 22:28
Reported-by: syzbot+71c4697e27c99fddcf17@syzkaller.appspotmail.com
Fix commit: f26c08b4 io_uring: fix file leak on error path of io ctx creation
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386]
First crash: 152d, last: 56d

Sample crash report:

BUG: memory leak
unreferenced object 0xffff888101401300 (size 168):
  comm "syz-executor355", pid 8461, jiffies 4294953658 (age 32.400s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000caa0de2b>] prepare_creds+0x25/0x390 kernel/cred.c:258
    [<000000001821b99d>] copy_creds+0x3a/0x230 kernel/cred.c:358
    [<0000000022c32914>] copy_process+0x661/0x24d0 kernel/fork.c:1971
    [<00000000d3adca2d>] kernel_clone+0xf3/0x670 kernel/fork.c:2456
    [<00000000d11b7286>] __do_sys_clone+0x76/0xa0 kernel/fork.c:2573
    [<000000008280baad>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<00000000685d8cf0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff88810b0a6f20 (size 32):
  comm "syz-executor355", pid 8461, jiffies 4294953658 (age 32.400s)
  hex dump (first 32 bytes):
    b0 6e 93 00 81 88 ff ff 00 00 00 00 00 00 00 00  .n..............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000007d750ba1>] kmalloc include/linux/slab.h:557 [inline]
    [<000000007d750ba1>] kzalloc include/linux/slab.h:664 [inline]
    [<000000007d750ba1>] lsm_cred_alloc security/security.c:533 [inline]
    [<000000007d750ba1>] security_prepare_creds+0xa5/0xd0 security/security.c:1632
    [<00000000ba63fcc7>] prepare_creds+0x277/0x390 kernel/cred.c:285
    [<000000001821b99d>] copy_creds+0x3a/0x230 kernel/cred.c:358
    [<0000000022c32914>] copy_process+0x661/0x24d0 kernel/fork.c:1971
    [<00000000d3adca2d>] kernel_clone+0xf3/0x670 kernel/fork.c:2456
    [<00000000d11b7286>] __do_sys_clone+0x76/0xa0 kernel/fork.c:2573
    [<000000008280baad>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<00000000685d8cf0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff888101ea2200 (size 256):
  comm "syz-executor355", pid 8470, jiffies 4294953658 (age 32.400s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    20 59 03 01 81 88 ff ff 80 87 a8 10 81 88 ff ff   Y..............
  backtrace:
    [<000000002e0a7c5f>] kmem_cache_zalloc include/linux/slab.h:654 [inline]
    [<000000002e0a7c5f>] __alloc_file+0x1f/0x130 fs/file_table.c:101
    [<000000001a55b73a>] alloc_empty_file+0x69/0x120 fs/file_table.c:151
    [<00000000fb22349e>] alloc_file+0x33/0x1b0 fs/file_table.c:193
    [<000000006e1465bb>] alloc_file_pseudo+0xb2/0x140 fs/file_table.c:233
    [<000000007118092a>] anon_inode_getfile fs/anon_inodes.c:91 [inline]
    [<000000007118092a>] anon_inode_getfile+0xaa/0x120 fs/anon_inodes.c:74
    [<000000002ae99012>] io_uring_get_fd fs/io_uring.c:9198 [inline]
    [<000000002ae99012>] io_uring_create fs/io_uring.c:9377 [inline]
    [<000000002ae99012>] io_uring_setup+0x1125/0x1630 fs/io_uring.c:9411
    [<000000008280baad>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<00000000685d8cf0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci-upstream-gce-leak	2020/11/28 03:46	upstream	99c710c4	486f93ef	.config	log	report	syz	C	bernd.edlinger@hotmail.de, chris@chrisdown.name, dhowells@redhat.com, ebiederm@xmission.com, guro@fb.com, keescook@chromium.org, linux-kernel@vger.kernel.org, shakeelb@google.com
ci-upstream-gce-leak	2020/11/19 23:33	upstream	3494d588	0767f13f	.config	log	report	syz		akpm@linux-foundation.org, bernd.edlinger@hotmail.de, chris@chrisdown.name, dhowells@redhat.com, ebiederm@xmission.com, keescook@chromium.org, linux-kernel@vger.kernel.org, shakeelb@google.com
ci-upstream-gce-leak	2020/08/23 22:21	upstream	c3d8f220	cef5ae68	.config	log	report	syz		akpm@linux-foundation.org, bernd.edlinger@hotmail.de, dhowells@redhat.com, ebiederm@xmission.com, keescook@chromium.org, linux-kernel@vger.kernel.org, mhocko@suse.com, shakeelb@google.com