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Tue, 3 Jul 2018 04:43:01 +0000 (GMT) Date: Tue, 03 Jul 2018 13:43:06 +0900 From: Seung-Woo Kim Reply-To: sw0312.kim@samsung.com User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Greg KH CC: linux-kernel@vger.kernel.org, Andrew Morton , torvalds@linux-foundation.org, stable@vger.kernel.org, lwn@lwn.net, Jiri Slaby , Seung-Woo Kim Subject: Re: Linux 3.18.111 In-Reply-To: <20180703043655.GA9793@kroah.com> Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: H4sIAAAAAAAAA01Se0hTYRTn825319nqa2od1sNxycjI5d2jbpIRFTVQyjCCHGUXvWziXuxu Zhm9UbNamUlzWtgLygx7OUoyy15mFoIlvaCwECySzDJMrO52i/rr+53fOef3O+f7PopQHyc1 VL7Ty3ucnJ0mlbLQnaTk5J6fqZaUwTI9W9vYQLK7TzWS7NBos5ztbq4l2bN3jsrYuku9iA1U 9pNsr/+TYjFlbg+MysytxxoU5lP+SrnZf7UemTvr7irMQ5enZ5LZ/EIbz+XxHi3vzHXl5Tut aXR6Vs7SHNO8FCaZWcDOp7VOzsGn0csyMpOX59vFgWhtIWf3iVQmJwj03EULPS6fl9faXII3 jbYwjF7HpMzX6fXiaVifqjeJJRt525GODrn7/NSi0PuPaAe6NbkcRVOAjfC5dq+iHCkpNb6G 4O3jfaQUfEHwcmQQScEwgs5vnehvS1tNh1xKtCAo2/UwSgo+IahqfycPV8lwIpzs7lWEMYnn QOvp0QivxlroagqQYRyP10Lg9sGIqgpPhIfV72VhHIdnQf+9l7KwKIFfI7j5/EkkEYunwNPO KxHRaKyDyvafkWYCJ8Duphoi3AD4Owljz36IbpSoWgilB0AaexkMvjskk3AsfHhwVSFhDQwN tJASLkVwu3qbpHMEQc/Ylz9FBug7UR4V1iRwEjQ2z5V8x8PAt/0RK8AqKCtRS9Uz4Pq9w6RE ayB4MUuizVDS1UJId1UZBbX+VuIQ0gb/Wz/43zbBf2Z1iKhHk3i34LDyAuM26gTOIficVl2u y3EZRf7mbPYauvEkow1hCtHjVEUJqRa1nCsUNjvaEFAEHacKJYqUKo/bvIX3uHI8PjsvtCGT +FIVhCY+1yX+dKc3hzHpDQYDa2TmmRiGnqwqeoEtamzlvHwBz7t5z9++KCpaswPtrNCccySO OdO7Z75ZkjuS3pS9vn/qyDnL/SX+H/CqZ5py65rYQKF7+MzqDFfChOKqR+rmFYnk/oKCVXGf VwZDRmtD8ceVb/fU2Ers1aXFXduTQof7KjKzU389Pzi866tRGaqPmXZ/oDzrF6M0xPirfDFj BVtXr+ubUrNuw/n4C5sUtEywccxswiNwvwH+Uy0NsQMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpkkeLIzCtJLcpLzFFi42LZdlhJXvfqP6tog66tNhZz1q9hs2hevJ7N 4vPvXawWl3fNYbNYcXg6i8WCjY8YLWZMfslm8ajvLbsDh8eJGb9ZPPbPXcPusbhvMqtH35ZV jB5nFhxh9/i8SS6ALYrLJiU1J7MstUjfLoErY8qpU6wFq2Uqtj15zdjAeEC8i5GTQ0LAROLQ 7FOsXYxcHEICuxkltv37wAKRkJKY+207YxcjB5AtLHH4cDFEzWtGiZufXzOD1PAKaEl86r/J BGKzCKhKLLr8iB3EZhPQkdi/5DcriC0koCBxYesMNhBbVCBE4tfHK6wQvYISJ2c+AdslIqAh 8fLoLRaQBcwC9xglFh/aBlYkLCAtceXMZnaIzb1MEm0bDoBt5hTQk5h84h/YdcwC6hLr5wmB hJkF5CWat85mnsAoNAvJjlkIVbOQVC1gZF7FKJlaUJybnltsWGCYl1quV5yYW1yal66XnJ+7 iREcMVqaOxgvL4k/xCjAwajEw3tB0SpaiDWxrLgy9xCjBAezkgjvNlWgEG9KYmVValF+fFFp TmrxIUZpDhYlcd6neccihQTSE0tSs1NTC1KLYLJMHJxSDYxxa2/ryEfNnRh/fQaj2MyNerXT 4/78EKq9ws6qsPhL85w7nTc6BDntAkTyriTWRXrPUW4/3Fd1YtPHFcvtBC96/rg77cixAj8e zemT5bxOlLmUNTnGRB2clcotPqu67LbnrtRjEil1HEVfD3V/ebX43Ns7Kon/4yZxWt9/K2nI w/qf+4hd3lwlluKMREMt5qLiRABa5YwSlAIAAA== Message-Id: <20180703044302epcas1p4ff5961129c010a2df3548cf678b6274c~9wjUy-vFW2959129591epcas1p4p@epcas1p4.samsung.com> X-CMS-MailID: 20180703044302epcas1p4ff5961129c010a2df3548cf678b6274c X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20180530073304epcas3p4967df82d2d086fd08fd354781df61861 References: <20180530073211.GA22422@kroah.com> <20180703032456epcas1p29c4570ae3f6bb3f8d7c2d475e1ba4658~9vfIpgNT51989519895epcas1p2d@epcas1p2.samsung.com> <20180703043655.GA9793@kroah.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018년 07월 03일 13:36, Greg KH wrote: > 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 >>> >>> ------------ >> >> >> >>> 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: >> [] down_read+0x24/0x54 >> [] ext4_xattr_get+0x74/0x1f4 >> [] ext4_xattr_security_get+0x28/0x38 >> [] generic_getxattr+0x4c/0x60 >> [] smk_fetch.isra.6+0x8c/0xe0 >> [] smack_d_instantiate+0x194/0x324 >> [] security_d_instantiate+0x24/0x30 >> [] d_instantiate_new+0x34/0x94 >> [] ext4_mkdir+0x284/0x354 >> [] vfs_mkdir+0xc0/0x150 >> [] SyS_mkdirat+0x88/0xb8 >> [] 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? I think the commit itself is required. Simple, but not reliable, workaround fix is like below: diff --git a/fs/dcache.c b/fs/dcache.c index a34d401..7c751f2 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1879,6 +1879,8 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode) BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); BUG_ON(!inode); lockdep_annotate_inode_mutex_key(inode); + /* WORKAROUND for calling security_d_instantiate() */ + entry->d_inode = inode; security_d_instantiate(entry, inode); spin_lock(&inode->i_lock); __d_instantiate(entry, inode); --- But I am not familiar with dentry/inode locking and there is no lock consideration at all. Thanks, - Seung-Woo Kim > > thanks, > > greg k-h > > > -- Seung-Woo Kim Samsung Research --