linux-kernel - Re: memory leak in prepare

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Date:   Fri, 27 Nov 2020 19:47:15 -0800
From:   syzbot <syzbot+71c4697e27c99fddcf17@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, bernd.edlinger@...mail.de,
        chris@...isdown.name, dhowells@...hat.com, ebiederm@...ssion.com,
        guro@...com, keescook@...omium.org, linux-kernel@...r.kernel.org,
        mhocko@...e.com, shakeelb@...gle.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: memory leak in prepare_creds

syzbot has found a reproducer for the following issue on:

HEAD commit:    99c710c4 Merge tag 'platform-drivers-x86-v5.10-2' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a77ddd500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c7a27a77f20fbc95
dashboard link: https://syzkaller.appspot.com/bug?extid=71c4697e27c99fddcf17
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12d6161d500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16f15e65500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+71c4697e27c99fddcf17@...kaller.appspotmail.com

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