Subject: [PATCH v3 01/12] clk: Fix debugfs reparenting NULL pointer dereference

From: [email-masked] (Stephen Boyd)
Date: Wed, 16 Oct 2013 00:40:03 -0700

Adding clocks from a kernel module can cause a NULL pointer
dereference if the parent of a clock is added after the clock is
added. This happens because __clk_init() iterates over the list
of orphans and reparents the orphans to the clock being
registered before creating the debugfs entry for the clock.
Create the debugfs entry first before reparenting the orphans.

Unable to handle kernel NULL pointer dereference at virtual address 00000028
pgd = ef3e4000
[00000028] *pgd=bf810831
Internal error: Oops: 17 [#1] PREEMPT SMP ARM
Modules linked in: mmcc_8960(+)
CPU: 0 PID: 52 Comm: modprobe Not tainted 3.12.0-rc2-00023-g1021a28-dirty #659
task: ef319200 ti: ef3a6000 task.ti: ef3a6000
PC is at lock_rename+0x24/0xc4
LR is at debugfs_rename+0x34/0x208
pc : [<c0317238>]    lr : [<c047dfe4>]    psr: 00000013
sp : ef3a7b88  ip : ef3a7ba8  fp : ef3a7ba4
r10: ef3d51cc  r9 : ef3bc680  r8 : ef3d5210
r7 : ef3bc640  r6 : eee287e0  r5 : eee287e0  r4 : 00000000
r3 : ef3bc640  r2 : 00000000  r1 : eee287e0  r0 : 00000000
Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 10c5787d  Table: af3e406a  DAC: 00000015
Process modprobe (pid: 52, stack limit = 0xef3a6240)
Stack: (0xef3a7b88 to 0xef3a8000)
7b80:                   ef3bc640 ee4047e0 00000000 eee287e0 ef3a7bec ef3a7ba8
7ba0: c047dfe4 c0317220 ef3bc680 ef3d51cc ef3a7bdc ef3a7bc0 c06e29d0 c0268784
7bc0: c08946e8 ef3d5210 00000000 ef3bc700 ef3d5290 ef3d5210 ef3bc680 ef3d51cc
7be0: ef3a7c0c ef3a7bf0 c05b9e9c c047dfbc 00000000 00000000 ef3d5210 ef3d5290
7c00: ef3a7c24 ef3a7c10 c05baebc c05b9e30 00000001 00000001 ef3a7c64 ef3a7c28
7c20: c05bb124 c05bae9c bf000cd8 ef3bc7c0 000000d0 c0ff129c bf001774 00000002
7c40: ef3bc740 ef3d5290 ef0f9a10 bf001774 bf00042c 00000061 ef3a7c8c ef3a7c68
7c60: c05bb480 c05baed8 bf001774 ef3d5290 ef0f9a10 bf001774 ef38bc10 ef0f9a00
7c80: ef3a7cac ef3a7c90 c05bb5a8 c05bb3a0 bf001774 00000062 ef0f9a10 ef38bc18
7ca0: ef3a7cec ef3a7cb0 bf00010c c05bb56c 00000000 ef38ba00 00000000 ef3d60d0
7cc0: ef3a7cdc c0fefc24 ef0f9a10 c0a091c0 bf000d24 00000000 bf0029f0 bf006000
7ce0: ef3a7cfc ef3a7cf0 c05156c0 bf000040 ef3a7d2c ef3a7d00 c0513f5c c05156a8
7d00: ef3a7d2c ef0f9a10 ef0f9a10 bf000d24 ef0f9a44 c09ca588 00000000 bf006000
7d20: ef3a7d4c ef3a7d30 c05142b8 c0513ecc ef0fd25c 00000000 bf000d24 c0514214
7d40: ef3a7d74 ef3a7d50 c0512030 c0514220 ef0050a8 ef0fd250 ef0050f8 bf000d24
7d60: ef37c100 c09ed150 ef3a7d84 ef3a7d78 c05139c8 c0511fd8 ef3a7
7d80: c051344c c05139a8 bf000864 c09ca588 ef3a7db4 bf000d24 bf002
7da0: c09ca588 00000000 ef3a7dcc ef3a7db8 c05149dc c0513360 ef3a7
7dc0: ef3a7ddc ef3a7dd0 c0515914 c0514960 ef3a7dec ef3a7de0 bf006
7de0: ef3a7e74 ef3a7df0 c0208800 bf00600c ef3a7e1c ef3a7e00 c04c5
7e00: ffffffff c09d46c4 00000000 bf0029a8 ef3a7e34 ef3a7e20 c024c
7e20: ffffffff c09d46c4 ef3a7e5c ef3a7e38 c024e2fc c024ce40 00000
7e40: ef3a7f48 bf0029b4 bf0029a8 271aeb1c ef3a7f48 bf0029a8 00000001 ef383c00
7e60: bf0029f0 00000001 ef3a7f3c ef3a7e78 c028fac4 c0208718 bf0029b4 00007fff
7e80: c028cd58 000000d2 f0065000 00000000 ef3a7ebc 00000000 00000000 bf0029b4
7ea0: 00000000 bf0029ac bf0029b4 ef3a6000 ef3a7efc c08bf128 00000000 00000000
7ec0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
7ee0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
7f00: 00000000 00000000 00000000 271aeb1c ef3a7f2c 00016376 b6f38008 001d3774
7f20: 00000080 c020f968 ef3a6000 00000000 ef3a7fa4 ef3a7f40 c02904dc c028e178
7f40: c020f898 010ccfa8 f0065000 00016376 f0073f60 f0073d7d f007a1e8 00002b24
7f60: 000039e4 00000000 00000000 00000000 0000002f 00000030 00000019 00000016
7f80: 00000012 00000000 00000000 010de1b2 b6f38008 010ccfa8 00000000 ef3a7fa8
7fa0: c020f6c0 c0290434 010de1b2 b6f38008 b6f38008 00016376 001d3774 00000000
7fc0: 010de1b2 b6f38008 010ccfa8 00000080 010de1b2 bedb6f90 010de1c9 0001d8dc
7fe0: 0000000c bedb674c 0001ce30 000094c4 60000010 b6f38008 00000008 0000001d
[<c0317238>] (lock_rename+0x24/0xc4) from [<c047dfe4>] (debugfs_rename+0x34/0x208)
[<c047dfe4>] (debugfs_rename+0x34/0x208) from [<c05b9e9c>] (clk_debug_reparent+0x78/0xc0)
[<c05baebc>] (__clk_reparent+0x2c/0x3c) from [<c05bb124>] (__clk_init+0x258/0x4c8)
[<c05bb124>] (__clk_init+0x258/0x4c8) from [<c05bb480>] (_clk_register+0xec/0x1cc)
[<c05bb480>] (_clk_register+0xec/0x1cc) from [<c05bb5a8>] (devm_clk_register+0x48/0x7c)
[<c05bb5a8>] (devm_clk_register+0x48/0x7c) from [<bf00010c>] (msm_mmcc_8960_probe+0xd8/0x190 [mmcc_8960])
[<bf00010c>] (msm_mmcc_8960_probe+0xd8/0x190 [mmcc_8960]) from [<c05156c0>] (platform_drv_probe+0x24/0x28)
[<c05156c0>] (platform_drv_probe+0x24/0x28) from [<c0513f5c>] (driver_probe_device+0x9c/0x354)
[<c0513f5c>] (driver_probe_device+0x9c/0x354) from [<c05142b8>] (__driver_attach+0xa4/0xa8)
[<c05142b8>] (__driver_attach+0xa4/0xa8) from [<c0512030>] (bus_for_each_dev+0x64/0x98)
[<c0512030>] (bus_for_each_dev+0x64/0x98) from [<c05139c8>] (driver_attach+0x2c/0x30)
[<c05139c8>] (driver_attach+0x2c/0x30) from [<c051344c>] (bus_add_driver+0xf8/0x2a8)
[<c051344c>] (bus_add_driver+0xf8/0x2a8) from [<c05149dc>] (driver_register+0x88/0x104)
[<c05149dc>] (driver_register+0x88/0x104) from [<c0515914>] (__platform_driver_register+0x58/0x6c)
[<c0515914>] (__platform_driver_register+0x58/0x6c) from [<bf006018>] (msm_mmcc_8960_driver_init+0x18/0x24 [mmcc_8960])
[<bf006018>] (msm_mmcc_8960_driver_init+0x18/0x24 [mmcc_8960]) from [<c0208800>] (do_one_initcall+0xf4/0x1b8)
[<c0208800>] (do_one_initcall+0xf4/0x1b8) from [<c028fac4>] (load_module+0x1958/0x22bc)
[<c028fac4>] (load_module+0x1958/0x22bc) from [<c02904dc>] (SyS_init_module+0xb4/0x120)
[<c02904dc>] (SyS_init_module+0xb4/0x120) from [<c020f6c0>] (ret_fast_syscall+0x0/0x48)
Code: e1500001 e1a04000 e1a05001 0a000021 (e5903028)

Signed-off-by: Stephen Boyd <[email-masked]>
---
 drivers/clk/clk.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index a004769..fbb5d59 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1737,6 +1737,7 @@ int __clk_init(struct device *dev, struct clk *clk)
 	else
 		clk->rate = 0;
 
+	clk_debug_register(clk);
 	/*
 	 * walk the list of orphan clocks and reparent any that are children of
 	 * this clock
@@ -1767,8 +1768,6 @@ int __clk_init(struct device *dev, struct clk *clk)
 	if (clk->ops->init)
 		clk->ops->init(clk->hw);
 
-	clk_debug_register(clk);
-
 out:
 	clk_prepare_unlock();
 
-- 
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