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%3Ba=summar...
thanks,
greg k-h
<snip.>
do d_instantiate/unlock_new_inode combinations safelyRecent 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