Re: [PATCH] clk: s2mps11: Fix double free corruption during driver unbind

[Yadwinder Singh Brar]

Hi Krzystof,

On Fri, Jun 27, 2014 at 4:04 PM, Krzysztof Kozlowski
<k.kozlowski@xxxxxxxxxxx> wrote:
> After unbinding the driver memory was corrupted by double free of
> clk_lookup structure. This lead to OOPS when re-binding the driver
> again.
>
> The driver allocated memory for 'clk_lookup' with devm_kzalloc. During
> driver removal this memory was freed twice: once by clkdev_drop() and
> second by devm code.
>

Ideally memory should be allocated and deallocated in same place
either driver or framework, so in this case if framework(clkdev_drop)
deallocates memory, framework itself should also allocate it.
So IMO this bug should be fixed using clkdev_alloc() instead of kzalloc().

Regards,
Yadwinder

> Kernel panic log:
> [   30.839284] Unable to handle kernel paging request at virtual address 5f343173
> [   30.846476] pgd = dee14000
> [   30.849165] [5f343173] *pgd=00000000
> [   30.852703] Internal error: Oops: 805 [#1] PREEMPT SMP ARM
> [   30.858166] Modules linked in:
> [   30.861208] CPU: 0 PID: 1 Comm: bash Not tainted 3.16.0-rc2-00239-g94bdf617b07e-dirty #40
> [   30.869364] task: df478000 ti: df480000 task.ti: df480000
> [   30.874752] PC is at clkdev_add+0x2c/0x38
> [   30.878738] LR is at clkdev_add+0x18/0x38
> [   30.882732] pc : [<c0350908>]    lr : [<c03508f4>]    psr: 60000013
> [   30.882732] sp : df481e78  ip : 00000001  fp : c0700ed8
> [   30.894187] r10: 0000000c  r9 : 00000000  r8 : c07b0e3c
> [   30.899396] r7 : 00000002  r6 : df45f9d0  r5 : df421390  r4 : c0700d6c
> [   30.905906] r3 : 5f343173  r2 : c0700d84  r1 : 60000013  r0 : c0700d6c
> [   30.912417] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
> [   30.919534] Control: 10c53c7d  Table: 5ee1406a  DAC: 00000015
> [   30.925262] Process bash (pid: 1, stack limit = 0xdf480240)
> [   30.930817] Stack: (0xdf481e78 to 0xdf482000)
> [   30.935159] 1e60:                                                       00001000 df6de610
> [   30.943321] 1e80: df7f4558 c0355650 c05ec6ec c0700eb0 df6de600 df7f4510 dec9d69c 00000014
> [   30.951480] 1ea0: 00167b48 df6de610 c0700e30 c0713518 00000000 c0700e30 dec9d69c 00000006
> [   30.959639] 1ec0: 00167b48 c02c1b7c c02c1b64 df6de610 c07aff48 c02c0420 c06fb150 c047cc20
> [   30.967798] 1ee0: df6de610 df6de610 c0700e30 df6de644 c06fb150 0000000c dec9d690 c02bef90
> [   30.975957] 1f00: dec9c6c0 dece4c00 df481f80 dece4c00 0000000c c02be73c 0000000c c016ca8c
> [   30.984116] 1f20: c016ca48 00000000 00000000 c016c1f4 00000000 00000000 b6f18000 df481f80
> [   30.992276] 1f40: df7f66c0 0000000c df480000 df480000 b6f18000 c011094c df47839c 60000013
> [   31.000435] 1f60: 00000000 00000000 df7f66c0 df7f66c0 0000000c df480000 b6f18000 c0110dd4
> [   31.008594] 1f80: 00000000 00000000 0000000c b6ec05d8 0000000c b6f18000 00000004 c000f2a8
> [   31.016753] 1fa0: 00001000 c000f0e0 b6ec05d8 0000000c 00000001 b6f18000 0000000c 00000000
> [   31.024912] 1fc0: b6ec05d8 0000000c b6f18000 00000004 0000000c 00000001 00000000 00167b48
> [   31.033071] 1fe0: 00000000 bed83a80 b6e004f0 b6e5122c 60000010 00000001 ffffffff ffffffff
> [   31.041248] [<c0350908>] (clkdev_add) from [<c0355650>] (s2mps11_clk_probe+0x2b4/0x3b4)
> [   31.049223] [<c0355650>] (s2mps11_clk_probe) from [<c02c1b7c>] (platform_drv_probe+0x18/0x48)
> [   31.057728] [<c02c1b7c>] (platform_drv_probe) from [<c02c0420>] (driver_probe_device+0x13c/0x384)
> [   31.066579] [<c02c0420>] (driver_probe_device) from [<c02bef90>] (bind_store+0x88/0xd8)
> [   31.074564] [<c02bef90>] (bind_store) from [<c02be73c>] (drv_attr_store+0x20/0x2c)
> [   31.082118] [<c02be73c>] (drv_attr_store) from [<c016ca8c>] (sysfs_kf_write+0x44/0x48)
> [   31.090016] [<c016ca8c>] (sysfs_kf_write) from [<c016c1f4>] (kernfs_fop_write+0xc0/0x17c)
> [   31.098176] [<c016c1f4>] (kernfs_fop_write) from [<c011094c>] (vfs_write+0xa0/0x1c4)
> [   31.105899] [<c011094c>] (vfs_write) from [<c0110dd4>] (SyS_write+0x40/0x8c)
> [   31.112931] [<c0110dd4>] (SyS_write) from [<c000f0e0>] (ret_fast_syscall+0x0/0x3c)
> [   31.120481] Code: e2842018 e584501c e1a00004 e885000c (e5835000)
> [   31.126596] ---[ end trace efad45bfa3a61b05 ]---
> [   31.131181] Kernel panic - not syncing: Fatal exception
> [   31.136368] CPU1: stopping
> [   31.139054] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G      D       3.16.0-rc2-00239-g94bdf617b07e-dirty #40
> [   31.148697] [<c0016480>] (unwind_backtrace) from [<c0012950>] (show_stack+0x10/0x14)
> [   31.156419] [<c0012950>] (show_stack) from [<c0480db8>] (dump_stack+0x80/0xcc)
> [   31.163622] [<c0480db8>] (dump_stack) from [<c001499c>] (handle_IPI+0x130/0x15c)
> [   31.170998] [<c001499c>] (handle_IPI) from [<c000862c>] (gic_handle_irq+0x60/0x68)
> [   31.178549] [<c000862c>] (gic_handle_irq) from [<c0013480>] (__irq_svc+0x40/0x70)
> [   31.186009] Exception stack(0xdf4bdf88 to 0xdf4bdfd0)
> [   31.191046] df80:                   ffffffed 00000000 00000000 00000000 df4bc000 c06d042c
> [   31.199207] dfa0: 00000000 ffffffed c06d03c0 00000000 c070c288 00000000 00000000 df4bdfd0
> [   31.207363] dfc0: c0010324 c0010328 60000013 ffffffff
> [   31.212402] [<c0013480>] (__irq_svc) from [<c0010328>] (arch_cpu_idle+0x28/0x30)
> [   31.219783] [<c0010328>] (arch_cpu_idle) from [<c005f150>] (cpu_startup_entry+0x2c4/0x3f0)
> [   31.228027] [<c005f150>] (cpu_startup_entry) from [<400086c4>] (0x400086c4)
> [   31.234968] ---[ end Kernel panic - not syncing: Fatal exception
>
> Fixes: 7cc560dea415 ("clk: s2mps11: Add support for s2mps11")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
> ---
>  drivers/clk/clk-s2mps11.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk-s2mps11.c b/drivers/clk/clk-s2mps11.c
> index 9b7b5859a420..27157f456ebe 100644
> --- a/drivers/clk/clk-s2mps11.c
> +++ b/drivers/clk/clk-s2mps11.c
> @@ -230,8 +230,8 @@ static int s2mps11_clk_probe(struct platform_device *pdev)
>                         goto err_reg;
>                 }
>
> -               s2mps11_clk->lookup = devm_kzalloc(&pdev->dev,
> -                                       sizeof(struct clk_lookup), GFP_KERNEL);
> +               s2mps11_clk->lookup = kzalloc(sizeof(struct clk_lookup),
> +                               GFP_KERNEL);
>                 if (!s2mps11_clk->lookup) {
>                         ret = -ENOMEM;
>                         goto err_lup;
> --
> 1.9.1
>
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