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authorChao Yu <chao2.yu@samsung.com>2014-07-24 17:25:42 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-10-30 09:35:13 -0700
commitf52c88e8e124f72eca2dc700c476b2b38f288f28 (patch)
parent26aca22946dc127ee5f72d031aa6dfe7f1328b44 (diff)
ecryptfs: avoid to access NULL pointer when write metadata in xattr
commit 35425ea2492175fd39f6116481fe98b2b3ddd4ca upstream. Christopher Head 2014-06-28 05:26:20 UTC described: "I tried to reproduce this on 3.12.21. Instead, when I do "echo hello > foo" in an ecryptfs mount with ecryptfs_xattr specified, I get a kernel crash: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff8110eb39>] fsstack_copy_attr_all+0x2/0x61 PGD d7840067 PUD b2c3c067 PMD 0 Oops: 0002 [#1] SMP Modules linked in: nvidia(PO) CPU: 3 PID: 3566 Comm: bash Tainted: P O 3.12.21-gentoo-r1 #2 Hardware name: ASUSTek Computer Inc. G60JX/G60JX, BIOS 206 03/15/2010 task: ffff8801948944c0 ti: ffff8800bad70000 task.ti: ffff8800bad70000 RIP: 0010:[<ffffffff8110eb39>] [<ffffffff8110eb39>] fsstack_copy_attr_all+0x2/0x61 RSP: 0018:ffff8800bad71c10 EFLAGS: 00010246 RAX: 00000000000181a4 RBX: ffff880198648480 RCX: 0000000000000000 RDX: 0000000000000004 RSI: ffff880172010450 RDI: 0000000000000000 RBP: ffff880198490e40 R08: 0000000000000000 R09: 0000000000000000 R10: ffff880172010450 R11: ffffea0002c51e80 R12: 0000000000002000 R13: 000000000000001a R14: 0000000000000000 R15: ffff880198490e40 FS: 00007ff224caa700(0000) GS:ffff88019fcc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000bb07f000 CR4: 00000000000007e0 Stack: ffffffff811826e8 ffff8800a39d8000 0000000000000000 000000000000001a ffff8800a01d0000 ffff8800a39d8000 ffffffff81185fd5 ffffffff81082c2c 00000001a39d8000 53d0abbc98490e40 0000000000000037 ffff8800a39d8220 Call Trace: [<ffffffff811826e8>] ? ecryptfs_setxattr+0x40/0x52 [<ffffffff81185fd5>] ? ecryptfs_write_metadata+0x1b3/0x223 [<ffffffff81082c2c>] ? should_resched+0x5/0x23 [<ffffffff8118322b>] ? ecryptfs_initialize_file+0xaf/0xd4 [<ffffffff81183344>] ? ecryptfs_create+0xf4/0x142 [<ffffffff810f8c0d>] ? vfs_create+0x48/0x71 [<ffffffff810f9c86>] ? do_last.isra.68+0x559/0x952 [<ffffffff810f7ce7>] ? link_path_walk+0xbd/0x458 [<ffffffff810fa2a3>] ? path_openat+0x224/0x472 [<ffffffff810fa7bd>] ? do_filp_open+0x2b/0x6f [<ffffffff81103606>] ? __alloc_fd+0xd6/0xe7 [<ffffffff810ee6ab>] ? do_sys_open+0x65/0xe9 [<ffffffff8157d022>] ? system_call_fastpath+0x16/0x1b RIP [<ffffffff8110eb39>] fsstack_copy_attr_all+0x2/0x61 RSP <ffff8800bad71c10> CR2: 0000000000000000 ---[ end trace df9dba5f1ddb8565 ]---" If we create a file when we mount with ecryptfs_xattr_metadata option, we will encounter a crash in this path: ->ecryptfs_create ->ecryptfs_initialize_file ->ecryptfs_write_metadata ->ecryptfs_write_metadata_to_xattr ->ecryptfs_setxattr ->fsstack_copy_attr_all It's because our dentry->d_inode used in fsstack_copy_attr_all is NULL, and it will be initialized when ecryptfs_initialize_file finish. So we should skip copying attr from lower inode when the value of ->d_inode is invalid. Signed-off-by: Chao Yu <chao2.yu@samsung.com> Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 5eab400e2590..41baf8b5e0eb 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -1051,7 +1051,7 @@ ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
rc = vfs_setxattr(lower_dentry, name, value, size, flags);
- if (!rc)
+ if (!rc && dentry->d_inode)
fsstack_copy_attr_all(dentry->d_inode, lower_dentry->d_inode);
return rc;