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    SubjectRe: Linux 3.18.111
    On Tue, Jul 03, 2018 at 12:24:59PM +0900, Seung-Woo Kim wrote:
    > Hello,
    >
    > On 2018년 05월 30일 16:32, Greg KH wrote:
    > > I'm announcing the release of the 3.18.111 kernel.
    > >
    > > All users of the 3.18 kernel series must upgrade.
    > >
    > > The updated 3.18.y git tree can be found at:
    > > git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-3.18.y
    > > and can be browsed at the normal kernel.org git web browser:
    > > http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary
    > >
    > > thanks,
    > >
    > > greg k-h
    > >
    > > ------------
    >
    > <snip.>
    >
    > > do d_instantiate/unlock_new_inode combinations safely
    >
    > Recent my test in 3.18.113 kernel with security smack showed following
    > crash during mkdir on ext4 fs.
    >
    > Unable to handle kernel paging request at virtual address ffffffffffffff98
    > pgd = ffffffc012411000
    > [ffffffffffffff98] *pgd=0000000000000000, *pud=0000000000000000
    > ------------[ cut here ]------------
    > Kernel BUG at ffffffc0007d9430 [verbose debug info unavailable]
    > Internal error: Oops - BUG: 96000005 [#1] PREEMPT SMP
    > CPU: 0 MPIDR: 80000000 PID: 1237 Comm: mkdir Not tainted
    > 3.18.113-00083-g1bfc02f-dirty #29-Tizen
    > task: ffffffc02cbc2340 ti: ffffffc02b7fc000 task.ti: ffffffc02b7fc000
    > PC is at down_read+0x24/0x54
    > LR is at down_read+0x24/0x54
    > [...]
    > Call trace:
    > [<ffffffc0007d9430>] down_read+0x24/0x54
    > [<ffffffc00022ff64>] ext4_xattr_get+0x74/0x1f4
    > [<ffffffc000234838>] ext4_xattr_security_get+0x28/0x38
    > [<ffffffc0001ab9f0>] generic_getxattr+0x4c/0x60
    > [<ffffffc0002786a0>] smk_fetch.isra.6+0x8c/0xe0
    > [<ffffffc000278888>] smack_d_instantiate+0x194/0x324
    > [<ffffffc000273794>] security_d_instantiate+0x24/0x30
    > [<ffffffc00019edf4>] d_instantiate_new+0x34/0x94
    > [<ffffffc0002046b4>] ext4_mkdir+0x284/0x354
    > [<ffffffc0001959bc>] vfs_mkdir+0xc0/0x150
    > [<ffffffc00019a108>] SyS_mkdirat+0x88/0xb8
    > [<ffffffc00019a150>] SyS_mkdir+0x18/0x20
    > Code: aa0003f3 b00017c0 912e1000 97e38943 (c85f7e60)
    > ---[ end trace b1ad797d63dae9c5 ]---
    >
    > It is because d_instantiate_new() added from above commit calls
    > security_d_instantiate() before calling __d_instantiate() and
    > dentry->d_inode is not yet set and null. In 3.18.113 kernel,
    > inode->i_op_getxattr() of ext4 is still generic_getxattr() and it only
    > has dentry parameter without inode, so it tries to access dentry->d_inode.
    >
    > I did not test with selinux, but selinux also calls
    > inode->i_op_getxattr() from selinux_d_instantiate(), so maybe there is
    > also same issue.

    So should I revert something or do you have a proposed fix for this?

    thanks,

    greg k-h

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