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Subject[ 023/149] sysfs: Fix memory leak in sysfs_sd_setsecdata().
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Masami Ichikawa <masami256@gmail.com>

commit 93518dd2ebafcc761a8637b2877008cfd748c202 upstream.

This patch fixies follwing two memory leak patterns that reported by kmemleak.
sysfs_sd_setsecdata() is called during sys_lsetxattr() operation.
It checks sd->s_iattr is NULL or not. Then if it is NULL, it calls
sysfs_init_inode_attrs() to allocate memory.
That code is this.

iattrs = sd->s_iattr;
if (!iattrs)
iattrs = sysfs_init_inode_attrs(sd);
The iattrs recieves sysfs_init_inode_attrs()'s result, but sd->s_iattr
doesn't know the address. so it needs to set correct address to
sd->s_iattr to free memory in other function.

unreferenced object 0xffff880250b73e60 (size 32):
comm "systemd", pid 1, jiffies 4294683888 (age 94.553s)
hex dump (first 32 bytes):
73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f system_u:object_
72 3a 73 79 73 66 73 5f 74 3a 73 30 00 00 00 00 r:sysfs_t:s0....
backtrace:
[<ffffffff814cb1d0>] kmemleak_alloc+0x73/0x98
[<ffffffff811270ab>] __kmalloc+0x100/0x12c
[<ffffffff8120775a>] context_struct_to_string+0x106/0x210
[<ffffffff81207cc1>] security_sid_to_context_core+0x10b/0x129
[<ffffffff812090ef>] security_sid_to_context+0x10/0x12
[<ffffffff811fb0da>] selinux_inode_getsecurity+0x7d/0xa8
[<ffffffff811fb127>] selinux_inode_getsecctx+0x22/0x2e
[<ffffffff811f4d62>] security_inode_getsecctx+0x16/0x18
[<ffffffff81191dad>] sysfs_setxattr+0x96/0x117
[<ffffffff811542f0>] __vfs_setxattr_noperm+0x73/0xd9
[<ffffffff811543d9>] vfs_setxattr+0x83/0xa1
[<ffffffff811544c6>] setxattr+0xcf/0x101
[<ffffffff81154745>] sys_lsetxattr+0x6a/0x8f
[<ffffffff814efda9>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffff88024163c5a0 (size 96):
comm "systemd", pid 1, jiffies 4294683888 (age 94.553s)
hex dump (first 32 bytes):
00 00 00 00 ed 41 00 00 00 00 00 00 00 00 00 00 .....A..........
00 00 00 00 00 00 00 00 0c 64 42 4f 00 00 00 00 .........dBO....
backtrace:
[<ffffffff814cb1d0>] kmemleak_alloc+0x73/0x98
[<ffffffff81127402>] kmem_cache_alloc_trace+0xc4/0xee
[<ffffffff81191cbe>] sysfs_init_inode_attrs+0x2a/0x83
[<ffffffff81191dd6>] sysfs_setxattr+0xbf/0x117
[<ffffffff811542f0>] __vfs_setxattr_noperm+0x73/0xd9
[<ffffffff811543d9>] vfs_setxattr+0x83/0xa1
[<ffffffff811544c6>] setxattr+0xcf/0x101
[<ffffffff81154745>] sys_lsetxattr+0x6a/0x8f
[<ffffffff814efda9>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
`
Signed-off-by: Masami Ichikawa <masami256@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/sysfs/inode.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -136,12 +136,13 @@ static int sysfs_sd_setsecdata(struct sy
void *old_secdata;
size_t old_secdata_len;

- iattrs = sd->s_iattr;
- if (!iattrs)
- iattrs = sysfs_init_inode_attrs(sd);
- if (!iattrs)
- return -ENOMEM;
+ if (!sd->s_iattr) {
+ sd->s_iattr = sysfs_init_inode_attrs(sd);
+ if (!sd->s_iattr)
+ return -ENOMEM;
+ }

+ iattrs = sd->s_iattr;
old_secdata = iattrs->ia_secdata;
old_secdata_len = iattrs->ia_secdata_len;




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