Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI device
proc file mmap(2)"), while fixing one problem, introduced two new ones:
- the function truncates the return value from ->get_unmapped_area() on
64-bit architectures,
- _all_ descendants are now required to set .get_unmapped_area to non-
NULL, which wasn't necessary before (and shouldn't be).
Both - afaict - are a result from a too simplistic copy'n'paste from
proc_reg_mmap() done in that change.
This likely also addresses reports like the one at
http://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729326.html.
Signed-off-by: Jan Beulich <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
---
fs/proc/inode.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- 3.12-rc5/fs/proc/inode.c
+++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c
@@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi
static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
- int rv = -EIO;
- unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
+ unsigned long rv = -EIO;
+
if (use_pde(pde)) {
- get_unmapped_area = pde->proc_fops->get_unmapped_area;
- if (get_unmapped_area)
- rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
+ rv = (pde->proc_fops->get_unmapped_area
+ ?: current->mm->get_unmapped_area)(file, orig_addr, len,
+ pgoff, flags);
unuse_pde(pde);
}
return rv;
On Wed, 16 Oct 2013 12:32:40 +0100 "Jan Beulich" <[email protected]> wrote:
> Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI device
> proc file mmap(2)"), while fixing one problem, introduced two new ones:
> - the function truncates the return value from ->get_unmapped_area() on
> 64-bit architectures,
> - _all_ descendants are now required to set .get_unmapped_area to non-
> NULL, which wasn't necessary before (and shouldn't be).
>
> Both - afaict - are a result from a too simplistic copy'n'paste from
> proc_reg_mmap() done in that change.
>
> This likely also addresses reports like the one at
> http://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729326.html.
>
> ...
>
> --- 3.12-rc5/fs/proc/inode.c
> +++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c
> @@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi
> static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
> {
> struct proc_dir_entry *pde = PDE(file_inode(file));
> - int rv = -EIO;
> - unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
> + unsigned long rv = -EIO;
> +
> if (use_pde(pde)) {
> - get_unmapped_area = pde->proc_fops->get_unmapped_area;
> - if (get_unmapped_area)
> - rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
> + rv = (pde->proc_fops->get_unmapped_area
> + ?: current->mm->get_unmapped_area)(file, orig_addr, len,
> + pgoff, flags);
> unuse_pde(pde);
> }
> return rv;
I think these two patches will address the problems:
http://ozlabs.org/~akpm/mmots/broken-out/procfs-fix-unintended-truncation-of-returned-mapped-address.patch
http://ozlabs.org/~akpm/mmots/broken-out/procfs-call-default-get_unmapped_area-on-mmu-present-architectures.patch
I'll be sending those Linuswards today. Please check them. (I think
your version would break the nommu build).
>>> On 16.10.13 at 22:40, Andrew Morton <[email protected]> wrote:
> On Wed, 16 Oct 2013 12:32:40 +0100 "Jan Beulich" <[email protected]> wrote:
>
>> Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI device
>> proc file mmap(2)"), while fixing one problem, introduced two new ones:
>> - the function truncates the return value from ->get_unmapped_area() on
>> 64-bit architectures,
>> - _all_ descendants are now required to set .get_unmapped_area to non-
>> NULL, which wasn't necessary before (and shouldn't be).
>>
>> Both - afaict - are a result from a too simplistic copy'n'paste from
>> proc_reg_mmap() done in that change.
>>
>> This likely also addresses reports like the one at
>>
> http://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729
> 326.html.
>>
>> ...
>>
>> --- 3.12-rc5/fs/proc/inode.c
>> +++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c
>> @@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi
>> static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned
> long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
>> {
>> struct proc_dir_entry *pde = PDE(file_inode(file));
>> - int rv = -EIO;
>> - unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned
> long, unsigned long, unsigned long);
>> + unsigned long rv = -EIO;
>> +
>> if (use_pde(pde)) {
>> - get_unmapped_area = pde->proc_fops->get_unmapped_area;
>> - if (get_unmapped_area)
>> - rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
>> + rv = (pde->proc_fops->get_unmapped_area
>> + ?: current->mm->get_unmapped_area)(file, orig_addr, len,
>> + pgoff, flags);
>> unuse_pde(pde);
>> }
>> return rv;
>
> I think these two patches will address the problems:
>
> http://ozlabs.org/~akpm/mmots/broken-out/procfs-fix-unintended-truncation-of-retur
> ned-mapped-address.patch
> http://ozlabs.org/~akpm/mmots/broken-out/procfs-call-default-get_unmapped_area-on-
> mmu-present-architectures.patch
>
> I'll be sending those Linuswards today. Please check them. (I think
> your version would break the nommu build).
Yes indeed - I did search for existing patches, but didn't find them.
I see Linus merged them already, so there's no point anymore
sending Reviewed-by tags.
I think though that in the !MMU case the second of them leaves an
issue unfixed nevertheless: If the specific procfs handler has no
.get_unmapped_area, the operation would still fail in that case
rather than succeed as it did before that wrapper got added.)
Jan
(2013/10/17 16:23), Jan Beulich wrote:
>>>> On 16.10.13 at 22:40, Andrew Morton <[email protected]> wrote:
>> On Wed, 16 Oct 2013 12:32:40 +0100 "Jan Beulich" <[email protected]> wrote:
>>
>>> Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI device
>>> proc file mmap(2)"), while fixing one problem, introduced two new ones:
>>> - the function truncates the return value from ->get_unmapped_area() on
>>> 64-bit architectures,
>>> - _all_ descendants are now required to set .get_unmapped_area to non-
>>> NULL, which wasn't necessary before (and shouldn't be).
>>>
>>> Both - afaict - are a result from a too simplistic copy'n'paste from
>>> proc_reg_mmap() done in that change.
>>>
>>> This likely also addresses reports like the one at
>>>
>> http://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729
>> 326.html.
>>>
>>> ...
>>>
>>> --- 3.12-rc5/fs/proc/inode.c
>>> +++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c
>>> @@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi
>>> static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned
>> long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
>>> {
>>> struct proc_dir_entry *pde = PDE(file_inode(file));
>>> - int rv = -EIO;
>>> - unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned
>> long, unsigned long, unsigned long);
>>> + unsigned long rv = -EIO;
>>> +
>>> if (use_pde(pde)) {
>>> - get_unmapped_area = pde->proc_fops->get_unmapped_area;
>>> - if (get_unmapped_area)
>>> - rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
>>> + rv = (pde->proc_fops->get_unmapped_area
>>> + ?: current->mm->get_unmapped_area)(file, orig_addr, len,
>>> + pgoff, flags);
>>> unuse_pde(pde);
>>> }
>>> return rv;
>>
>> I think these two patches will address the problems:
>>
>> http://ozlabs.org/~akpm/mmots/broken-out/procfs-fix-unintended-truncation-of-retur
>> ned-mapped-address.patch
>> http://ozlabs.org/~akpm/mmots/broken-out/procfs-call-default-get_unmapped_area-on-
>> mmu-present-architectures.patch
>>
>> I'll be sending those Linuswards today. Please check them. (I think
>> your version would break the nommu build).
>
> Yes indeed - I did search for existing patches, but didn't find them.
> I see Linus merged them already, so there's no point anymore
> sending Reviewed-by tags.
>
> I think though that in the !MMU case the second of them leaves an
> issue unfixed nevertheless: If the specific procfs handler has no
> .get_unmapped_area, the operation would still fail in that case
> rather than succeed as it did before that wrapper got added.)
>
> Jan
>
Yes, there remains difference on no-mmu that if mmap is not defined, mmap() now returns
EIO, it should return ENODEV.
In mm/nommu.c,
/* eliminate any capabilities that we can't support on this
* device */
if (!file->f_op->get_unmapped_area)
capabilities &= ~BDI_CAP_MAP_DIRECT;
and
*/
if (capabilities & BDI_CAP_MAP_DIRECT) {
addr = file->f_op->get_unmapped_area(file, addr, len,
pgoff, flags);
if (IS_ERR_VALUE(addr)) {
ret = addr;
if (ret != -ENOSYS)
goto error_just_free;
/* the driver refused to tell us where to site
* the mapping so we'll have to attempt to copy
* it */
ret = -ENODEV;
if (!(capabilities & BDI_CAP_MAP_COPY))
goto error_just_free;
capabilities &= ~BDI_CAP_MAP_DIRECT;
} else {
vma->vm_start = region->vm_start = addr;
vma->vm_end = region->vm_end = addr + len;
}
}
So, how about let proc_reg_get_unmapped_area() return ENOSYS, not EIO?
--
Thanks.
HATAYAMA, Daisuke
>>> On 17.10.13 at 10:36, HATAYAMA Daisuke <[email protected]> wrote:
> (2013/10/17 16:23), Jan Beulich wrote:
>>>>> On 16.10.13 at 22:40, Andrew Morton <[email protected]> wrote:
>>> On Wed, 16 Oct 2013 12:32:40 +0100 "Jan Beulich" <[email protected]> wrote:
>>>
>>>> Commit c4fe24485729fc2cbff324c111e67a1cc2f9adea ("sparc: fix PCI device
>>>> proc file mmap(2)"), while fixing one problem, introduced two new ones:
>>>> - the function truncates the return value from ->get_unmapped_area() on
>>>> 64-bit architectures,
>>>> - _all_ descendants are now required to set .get_unmapped_area to non-
>>>> NULL, which wasn't necessary before (and shouldn't be).
>>>>
>>>> Both - afaict - are a result from a too simplistic copy'n'paste from
>>>> proc_reg_mmap() done in that change.
>>>>
>>>> This likely also addresses reports like the one at
>>>>
>>>
> http://linux-kernel.2935.n7.nabble.com/mmap-for-proc-vmcore-broken-since-3-12-rc1-td729
>
>>> 326.html.
>>>>
>>>> ...
>>>>
>>>> --- 3.12-rc5/fs/proc/inode.c
>>>> +++ 3.12-rc5-proc-get-unmapped-area/fs/proc/inode.c
>>>> @@ -288,12 +288,12 @@ static int proc_reg_mmap(struct file *fi
>>>> static unsigned long proc_reg_get_unmapped_area(struct file *file,
> unsigned
>>> long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
>>>> {
>>>> struct proc_dir_entry *pde = PDE(file_inode(file));
>>>> - int rv = -EIO;
>>>> - unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned
>>> long, unsigned long, unsigned long);
>>>> + unsigned long rv = -EIO;
>>>> +
>>>> if (use_pde(pde)) {
>>>> - get_unmapped_area = pde->proc_fops->get_unmapped_area;
>>>> - if (get_unmapped_area)
>>>> - rv = get_unmapped_area(file, orig_addr, len, pgoff, flags);
>>>> + rv = (pde->proc_fops->get_unmapped_area
>>>> + ?: current->mm->get_unmapped_area)(file, orig_addr, len,
>>>> + pgoff, flags);
>>>> unuse_pde(pde);
>>>> }
>>>> return rv;
>>>
>>> I think these two patches will address the problems:
>>>
>>> http://ozlabs.org/~akpm/mmots/broken-out/procfs-fix-unintended-truncation-of-retur
>>> ned-mapped-address.patch
>>> http://ozlabs.org/~akpm/mmots/broken-out/procfs-call-default-get_unmapped_area-on-
>>> mmu-present-architectures.patch
>>>
>>> I'll be sending those Linuswards today. Please check them. (I think
>>> your version would break the nommu build).
>>
>> Yes indeed - I did search for existing patches, but didn't find them.
>> I see Linus merged them already, so there's no point anymore
>> sending Reviewed-by tags.
>>
>> I think though that in the !MMU case the second of them leaves an
>> issue unfixed nevertheless: If the specific procfs handler has no
>> .get_unmapped_area, the operation would still fail in that case
>> rather than succeed as it did before that wrapper got added.)
>>
>> Jan
>>
>
> Yes, there remains difference on no-mmu that if mmap is not defined, mmap()
> now returns
> EIO, it should return ENODEV.
No, afaict it should succeed (and simply use the address that came in).
Jan