memory leak in cap_inode_getsecurity

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    0f1a7b3f timer-of: don't use conditional expression with m..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1329640d600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9d66badf12ef344c
dashboard link: https://syzkaller.appspot.com/bug?extid=942d5390db2d9624ced8
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1107b513600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+942d5390db2d9624ced8@xxxxxxxxxxxxxxxxxxxxxxxxx

2019/10/03 14:00:37 executed programs: 36
2019/10/03 14:00:43 executed programs: 44
2019/10/03 14:00:49 executed programs: 63
BUG: memory leak
unreferenced object 0xffff8881202cb480 (size 32):
  comm "syz-executor.0", pid 7246, jiffies 4294946879 (age 14.010s)
  hex dump (first 32 bytes):
    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 00  ................
  backtrace:
    [<00000000a8379648>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:43 [inline]
    [<00000000a8379648>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<00000000a8379648>] slab_alloc mm/slab.c:3319 [inline]
    [<00000000a8379648>] __do_kmalloc mm/slab.c:3653 [inline]
    [<00000000a8379648>] __kmalloc_track_caller+0x165/0x300 mm/slab.c:3670
    [<000000008858463c>] __do_krealloc mm/slab_common.c:1638 [inline]
    [<000000008858463c>] krealloc+0x7f/0xb0 mm/slab_common.c:1689
    [<0000000057f9eb8e>] vfs_getxattr_alloc+0x100/0x180 fs/xattr.c:289
    [<00000000c2154e30>] cap_inode_getsecurity+0x9c/0x2c0  
security/commoncap.c:389
    [<00000000b2664a09>] security_inode_getsecurity+0x4c/0x90  
security/security.c:1314
    [<00000000921624c0>] xattr_getsecurity fs/xattr.c:244 [inline]
    [<00000000921624c0>] vfs_getxattr+0xf2/0x1a0 fs/xattr.c:332
    [<000000001ff6977b>] getxattr+0x97/0x240 fs/xattr.c:538
    [<00000000b945681f>] path_getxattr+0x6b/0xc0 fs/xattr.c:566
    [<000000001a9d3fce>] __do_sys_getxattr fs/xattr.c:578 [inline]
    [<000000001a9d3fce>] __se_sys_getxattr fs/xattr.c:575 [inline]
    [<000000001a9d3fce>] __x64_sys_getxattr+0x28/0x30 fs/xattr.c:575
    [<000000002e998337>] do_syscall_64+0x73/0x1f0  
arch/x86/entry/common.c:290
    [<00000000f252aa21>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



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