[RFC 02/10] module: fix memory leak on early load_module() failures

From: Luis R. Rodriguez
Date: Thu Dec 08 2016 - 14:48:13 EST


While looking for early possible module loading failures I was
able to reproduce a memory leak possible with kmemleak. There
are a few rare ways to trigger a failure:

o we've run into a failure while processing kernel parameters
(parse_args() returns an error)
o mod_sysfs_setup() fails
o we're a live patch module and copy_module_elf() fails

Chances of running into this issue is really low.

kmemleak splat:

unreferenced object 0xffff9f2c4ada1b00 (size 32):
comm "kworker/u16:4", pid 82, jiffies 4294897636 (age 681.816s)
hex dump (first 32 bytes):
6d 65 6d 73 74 69 63 6b 30 00 00 00 00 00 00 00 memstick0.......
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff8c6cfeba>] kmemleak_alloc+0x4a/0xa0
[<ffffffff8c200046>] __kmalloc_track_caller+0x126/0x230
[<ffffffff8c1bc581>] kstrdup+0x31/0x60
[<ffffffff8c1bc5d4>] kstrdup_const+0x24/0x30
[<ffffffff8c3c23aa>] kvasprintf_const+0x7a/0x90
[<ffffffff8c3b5481>] kobject_set_name_vargs+0x21/0x90
[<ffffffff8c4fbdd7>] dev_set_name+0x47/0x50
[<ffffffffc07819e5>] memstick_check+0x95/0x33c [memstick]
[<ffffffff8c09c893>] process_one_work+0x1f3/0x4b0
[<ffffffff8c09cb98>] worker_thread+0x48/0x4e0
[<ffffffff8c0a2b79>] kthread+0xc9/0xe0
[<ffffffff8c6dab5f>] ret_from_fork+0x1f/0x40
[<ffffffffffffffff>] 0xffffffffffffffff

Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
---
kernel/module.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/kernel/module.c b/kernel/module.c
index f7482db0f843..e420ed67e533 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3722,6 +3722,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
mod_sysfs_teardown(mod);
coming_cleanup:
mod->state = MODULE_STATE_GOING;
+ destroy_params(mod->kp, mod->num_kp);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
klp_module_going(mod);
--
2.10.1