linux-hardened/net/sysctl_net.c
Li RongQing ce9d9b8e5c net: sysctl: fix a kmemleak warning
the returned buffer of register_sysctl() is stored into net_header
variable, but net_header is not used after, and compiler maybe
optimise the variable out, and lead kmemleak reported the below warning

	comm "swapper/0", pid 1, jiffies 4294937448 (age 267.270s)
	hex dump (first 32 bytes):
	90 38 8b 01 c0 ff ff ff 00 00 00 00 01 00 00 00 .8..............
	01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
	backtrace:
	[<ffffffc00020f134>] create_object+0x10c/0x2a0
	[<ffffffc00070ff44>] kmemleak_alloc+0x54/0xa0
	[<ffffffc0001fe378>] __kmalloc+0x1f8/0x4f8
	[<ffffffc00028e984>] __register_sysctl_table+0x64/0x5a0
	[<ffffffc00028eef0>] register_sysctl+0x30/0x40
	[<ffffffc00099c304>] net_sysctl_init+0x20/0x58
	[<ffffffc000994dd8>] sock_init+0x10/0xb0
	[<ffffffc0000842e0>] do_one_initcall+0x90/0x1b8
	[<ffffffc000966bac>] kernel_init_freeable+0x218/0x2f0
	[<ffffffc00070ed6c>] kernel_init+0x1c/0xe8
	[<ffffffc000083bfc>] ret_from_fork+0xc/0x50
	[<ffffffffffffffff>] 0xffffffffffffffff <<end check kmemleak>>

Before fix, the objdump result on ARM64:
0000000000000000 <net_sysctl_init>:
   0:   a9be7bfd        stp     x29, x30, [sp,#-32]!
   4:   90000001        adrp    x1, 0 <net_sysctl_init>
   8:   90000000        adrp    x0, 0 <net_sysctl_init>
   c:   910003fd        mov     x29, sp
  10:   91000021        add     x1, x1, #0x0
  14:   91000000        add     x0, x0, #0x0
  18:   a90153f3        stp     x19, x20, [sp,#16]
  1c:   12800174        mov     w20, #0xfffffff4                // #-12
  20:   94000000        bl      0 <register_sysctl>
  24:   b4000120        cbz     x0, 48 <net_sysctl_init+0x48>
  28:   90000013        adrp    x19, 0 <net_sysctl_init>
  2c:   91000273        add     x19, x19, #0x0
  30:   9101a260        add     x0, x19, #0x68
  34:   94000000        bl      0 <register_pernet_subsys>
  38:   2a0003f4        mov     w20, w0
  3c:   35000060        cbnz    w0, 48 <net_sysctl_init+0x48>
  40:   aa1303e0        mov     x0, x19
  44:   94000000        bl      0 <register_sysctl_root>
  48:   2a1403e0        mov     w0, w20
  4c:   a94153f3        ldp     x19, x20, [sp,#16]
  50:   a8c27bfd        ldp     x29, x30, [sp],#32
  54:   d65f03c0        ret
After:
0000000000000000 <net_sysctl_init>:
   0:   a9bd7bfd        stp     x29, x30, [sp,#-48]!
   4:   90000000        adrp    x0, 0 <net_sysctl_init>
   8:   910003fd        mov     x29, sp
   c:   a90153f3        stp     x19, x20, [sp,#16]
  10:   90000013        adrp    x19, 0 <net_sysctl_init>
  14:   91000000        add     x0, x0, #0x0
  18:   91000273        add     x19, x19, #0x0
  1c:   f90013f5        str     x21, [sp,#32]
  20:   aa1303e1        mov     x1, x19
  24:   12800175        mov     w21, #0xfffffff4                // #-12
  28:   94000000        bl      0 <register_sysctl>
  2c:   f9002260        str     x0, [x19,#64]
  30:   b40001a0        cbz     x0, 64 <net_sysctl_init+0x64>
  34:   90000014        adrp    x20, 0 <net_sysctl_init>
  38:   91000294        add     x20, x20, #0x0
  3c:   9101a280        add     x0, x20, #0x68
  40:   94000000        bl      0 <register_pernet_subsys>
  44:   2a0003f5        mov     w21, w0
  48:   35000080        cbnz    w0, 58 <net_sysctl_init+0x58>
  4c:   aa1403e0        mov     x0, x20
  50:   94000000        bl      0 <register_sysctl_root>
  54:   14000004        b       64 <net_sysctl_init+0x64>
  58:   f9402260        ldr     x0, [x19,#64]
  5c:   94000000        bl      0 <unregister_sysctl_table>
  60:   f900227f        str     xzr, [x19,#64]
  64:   2a1503e0        mov     w0, w21
  68:   f94013f5        ldr     x21, [sp,#32]
  6c:   a94153f3        ldp     x19, x20, [sp,#16]
  70:   a8c37bfd        ldp     x29, x30, [sp],#48
  74:   d65f03c0        ret

Add the possible error handle to free the net_header to remove the
kmemleak warning

Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-23 06:22:08 -07:00

118 lines
2.9 KiB
C

/* -*- linux-c -*-
* sysctl_net.c: sysctl interface to net subsystem.
*
* Begun April 1, 1996, Mike Shaver.
* Added /proc/sys/net directories for each protocol family. [MS]
*
* Revision 1.2 1996/05/08 20:24:40 shaver
* Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
* NET_IPV4_IP_FORWARD.
*
*
*/
#include <linux/mm.h>
#include <linux/export.h>
#include <linux/sysctl.h>
#include <linux/nsproxy.h>
#include <net/sock.h>
#ifdef CONFIG_INET
#include <net/ip.h>
#endif
#ifdef CONFIG_NET
#include <linux/if_ether.h>
#endif
static struct ctl_table_set *
net_ctl_header_lookup(struct ctl_table_root *root, struct nsproxy *namespaces)
{
return &namespaces->net_ns->sysctls;
}
static int is_seen(struct ctl_table_set *set)
{
return &current->nsproxy->net_ns->sysctls == set;
}
/* Return standard mode bits for table entry. */
static int net_ctl_permissions(struct ctl_table_header *head,
struct ctl_table *table)
{
struct net *net = container_of(head->set, struct net, sysctls);
kuid_t root_uid = make_kuid(net->user_ns, 0);
kgid_t root_gid = make_kgid(net->user_ns, 0);
/* Allow network administrator to have same access as root. */
if (ns_capable(net->user_ns, CAP_NET_ADMIN) ||
uid_eq(root_uid, current_euid())) {
int mode = (table->mode >> 6) & 7;
return (mode << 6) | (mode << 3) | mode;
}
/* Allow netns root group to have the same access as the root group */
if (in_egroup_p(root_gid)) {
int mode = (table->mode >> 3) & 7;
return (mode << 3) | mode;
}
return table->mode;
}
static struct ctl_table_root net_sysctl_root = {
.lookup = net_ctl_header_lookup,
.permissions = net_ctl_permissions,
};
static int __net_init sysctl_net_init(struct net *net)
{
setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
return 0;
}
static void __net_exit sysctl_net_exit(struct net *net)
{
retire_sysctl_set(&net->sysctls);
}
static struct pernet_operations sysctl_pernet_ops = {
.init = sysctl_net_init,
.exit = sysctl_net_exit,
};
static struct ctl_table_header *net_header;
__init int net_sysctl_init(void)
{
static struct ctl_table empty[1];
int ret = -ENOMEM;
/* Avoid limitations in the sysctl implementation by
* registering "/proc/sys/net" as an empty directory not in a
* network namespace.
*/
net_header = register_sysctl("net", empty);
if (!net_header)
goto out;
ret = register_pernet_subsys(&sysctl_pernet_ops);
if (ret)
goto out1;
register_sysctl_root(&net_sysctl_root);
out:
return ret;
out1:
unregister_sysctl_table(net_header);
net_header = NULL;
goto out;
}
struct ctl_table_header *register_net_sysctl(struct net *net,
const char *path, struct ctl_table *table)
{
return __register_sysctl_table(&net->sysctls, path, table);
}
EXPORT_SYMBOL_GPL(register_net_sysctl);
void unregister_net_sysctl_table(struct ctl_table_header *header)
{
unregister_sysctl_table(header);
}
EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);