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

[Mike Turquette]

Quoting Stephen Boyd (2013-10-16 00:40:03)
> 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 <sboyd at codeaurora.org>

Taken into clk-next. Thanks!

Mike

> ---
>  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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