Subject: [PATCH v2 2/2] iommu/omap: fix NULL pointer dereference

From: [email-masked] (Joerg Roedel)
Date: Thu, 23 Feb 2012 17:11:09 +0100

I guess these patches are 3.3 material? How about tagging them for
stable too?

On Wed, Feb 22, 2012 at 11:14:46AM +0200, Ohad Ben-Cohen wrote:
> Fix this:
> 
> root at omap4430-panda:~# cat /debug/iommu/ducati/mem
> [   62.725708] Unable to handle kernel NULL pointer dereference at virtual addre
> ss 0000001c
> [   62.725708] pgd = e6240000
> [   62.737091] [0000001c] *pgd=a7168831, *pte=00000000, *ppte=00000000
> [   62.743682] Internal error: Oops: 17 [#1] SMP
> [   62.743682] Modules linked in: omap_iommu_debug omap_iovmm virtio_rpmsg_bus o
> map_remoteproc remoteproc virtio_ring virtio mailbox_mach mailbox
> [   62.743682] CPU: 0    Not tainted  (3.3.0-rc1-00265-g382f84e-dirty #682)
> [   62.743682] PC is at debug_read_mem+0x5c/0xac [omap_iommu_debug]
> [   62.743682] LR is at 0x1004
> [   62.777832] pc : [<bf033178>]    lr : [<00001004>]    psr: 60000013
> [   62.777832] sp : e72c7f40  ip : c0763c00  fp : 00000001
> [   62.777832] r10: 00000000  r9 : 00000000  r8 : e72c7f80
> [   62.777832] r7 : e6ffdc08  r6 : bed1ac78  r5 : 00001000  r4 : e7276000
> [   62.777832] r3 : e60f3460  r2 : 00000000  r1 : e60f38c0  r0 : 00000000
> [   62.777832] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
> [   62.816375] Control: 10c53c7d  Table: a624004a  DAC: 00000015
> [   62.816375] Process cat (pid: 1176, stack limit = 0xe72c62f8)
> [   62.828369] Stack: (0xe72c7f40 to 0xe72c8000)
> ...
> [   62.884185] [<bf033178>] (debug_read_mem+0x5c/0xac [omap_iommu_debug]) from [
> <c010e354>] (vfs_read+0xac/0x130)
> [   62.884185] [<c010e354>] (vfs_read+0xac/0x130) from [<c010e4a8>] (sys_read+0x
> 40/0x70)
> [   62.884185] [<c010e4a8>] (sys_read+0x40/0x70) from [<c0014a00>] (ret_fast_sys
> call+0x0/0x3c)
> 
> Fix also its 'echo bla > /debug/iommu/ducati/mem' Oops sibling, too.
> 
> Signed-off-by: Ohad Ben-Cohen <[email-masked]>
> Cc: Tony Lindgren <[email-masked]>
> Cc: Hiroshi Doyu <[email-masked]>
> Cc: Laurent Pinchart <[email-masked]>
> Cc: Russell King <[email-masked]>
> Cc: Joerg Roedel <[email-masked]>
> ---
> v2: omap_find_iovm_area only returns NULL for errors. thanks, rmk.
> 
>  drivers/iommu/omap-iommu-debug.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/omap-iommu-debug.c b/drivers/iommu/omap-iommu-debug.c
> index bad9f9d..103dbd9 100644
> --- a/drivers/iommu/omap-iommu-debug.c
> +++ b/drivers/iommu/omap-iommu-debug.c
> @@ -274,7 +274,7 @@ static ssize_t debug_read_mem(struct file *file, char __user *userbuf,
>  	mutex_lock(&iommu_debug_lock);
>  
>  	area = omap_find_iovm_area(dev, (u32)ppos);
> -	if (IS_ERR(area)) {
> +	if (!area) {
>  		bytes = -EINVAL;
>  		goto err_out;
>  	}
> @@ -311,7 +311,7 @@ static ssize_t debug_write_mem(struct file *file, const char __user *userbuf,
>  	}
>  
>  	area = omap_find_iovm_area(dev, (u32)ppos);
> -	if (IS_ERR(area)) {
> +	if (!area) {
>  		count = -EINVAL;
>  		goto err_out;
>  	}
> -- 
> 1.7.5.4
> 

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