diff options
author | Chao Yu <chao2.yu@samsung.com> | 2014-07-24 17:25:42 +0800 |
---|---|---|
committer | Tyler Hicks <tyhicks@canonical.com> | 2014-10-05 23:51:43 -0500 |
commit | 35425ea2492175fd39f6116481fe98b2b3ddd4ca (patch) | |
tree | 147d32b621eb1000a5a065a4e1f82f3237c57728 | |
parent | 04ec5f5c0022ee941615e304bc75853fe1bc94ba (diff) |
ecryptfs: avoid to access NULL pointer when write metadata in xattr
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>
Cc: stable@vger.kernel.org # v3.2+: b59db43 eCryptfs: Prevent file create race condition
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
-rw-r--r-- | fs/ecryptfs/inode.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c index a27121d35b23..7e405396dc05 100644 --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -1040,7 +1040,7 @@ 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); out: return rc; |