@@ -436,18 +436,15 @@ static int proc_sctp_do_auth(struct ctl_table *ctl, int write,
int sctp_sysctl_net_register(struct net *net)
{
- struct ctl_table *table = sctp_net_table;
-
- if (!net_eq(net, &init_net)) {
- int i;
+ struct ctl_table *table;
+ int i;
- table = kmemdup(sctp_net_table, sizeof(sctp_net_table), GFP_KERNEL);
- if (!table)
- return -ENOMEM;
+ table = kmemdup(sctp_net_table, sizeof(sctp_net_table), GFP_KERNEL);
+ if (!table)
+ return -ENOMEM;
- for (i = 0; table[i].data; i++)
- table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;
- }
+ for (i = 0; table[i].data; i++)
+ table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;
net->sctp.sysctl_header = register_net_sysctl(net, "net/sctp", table);
return 0;
This revert commit efb842c45("sctp: optimize the sctp_sysctl_net_register"), Since it doesn't kmemdup a sysctl_table for init_net, so the init_net->sctp.sysctl_header->ctl_table_arg points to sctp_net_table which is a static array pointer. So when doing sctp_sysctl_net_unregister, it will free sctp_net_table, then we will get a NULL pointer dereference like that: [ 262.948220] BUG: unable to handle kernel NULL pointer dereference at 000000000000006c [ 262.948232] IP: [<ffffffff81144b70>] kfree+0x80/0x420 [ 262.948260] PGD db80a067 PUD dae12067 PMD 0 [ 262.948268] Oops: 0000 [#1] SMP [ 262.948273] Modules linked in: sctp(-) crc32c_generic libcrc32c ... [ 262.948338] task: ffff8800db830190 ti: ffff8800dad00000 task.ti: ffff8800dad00000 [ 262.948344] RIP: 0010:[<ffffffff81144b70>] [<ffffffff81144b70>] kfree+0x80/0x420 [ 262.948353] RSP: 0018:ffff8800dad01d88 EFLAGS: 00010046 [ 262.948358] RAX: 0100000000000000 RBX: ffffffffa0227940 RCX: ffffea0000707888 [ 262.948363] RDX: ffffea0000707888 RSI: 0000000000000001 RDI: ffffffffa0227940 [ 262.948369] RBP: ffff8800dad01de8 R08: 0000000000000000 R09: ffff8800d9e983a9 [ 262.948374] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa0227940 [ 262.948380] R13: ffffffff8187cfc0 R14: 0000000000000000 R15: ffffffff8187da10 [ 262.948386] FS: 00007fa2a2658700(0000) GS:ffff880112800000(0000) knlGS:0000000000000000 [ 262.948394] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 262.948400] CR2: 000000000000006c CR3: 00000000cddc0000 CR4: 00000000000006e0 [ 262.948410] Stack: [ 262.948413] ffff8800dad01da8 0000000000000286 0000000020227940 ffffffffa0227940 [ 262.948422] ffff8800dad01dd8 ffffffff811b7fa1 ffffffffa0227940 ffffffffa0227940 [ 262.948431] ffffffff8187d960 ffffffff8187cfc0 ffffffff8187d960 ffffffff8187da10 [ 262.948440] Call Trace: [ 262.948457] [<ffffffff811b7fa1>] ? unregister_sysctl_table+0x51/0xa0 [ 262.948476] [<ffffffffa020d1a1>] sctp_sysctl_net_unregister+0x21/0x30 [sctp] [ 262.948490] [<ffffffffa020ef6d>] sctp_net_exit+0x12d/0x150 [sctp] [ 262.948512] [<ffffffff81394f49>] ops_exit_list+0x39/0x60 [ 262.948522] [<ffffffff813951ed>] unregister_pernet_operations+0x3d/0x70 [ 262.948530] [<ffffffff81395292>] unregister_pernet_subsys+0x22/0x40 [ 262.948544] [<ffffffffa020efcc>] sctp_exit+0x3c/0x12d [sctp] [ 262.948562] [<ffffffff810c5e04>] SyS_delete_module+0x194/0x210 [ 262.948577] [<ffffffff81240fde>] ? trace_hardirqs_on_thunk+0x3a/0x3f [ 262.948587] [<ffffffff815217a2>] system_call_fastpath+0x16/0x1b With this revert, it won't occur the Oops. Signed-off-by: Wang Weidong <wangweidong1@huawei.com> --- net/sctp/sysctl.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)