[PATCH] elf: don't hash userspace addresses

[PATCH] elf: don't hash userspace addresses

[Alexey Dobriyan]

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

 fs/binfmt_elf.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -379,8 +379,8 @@ static unsigned long elf_map(struct file *filep, unsigned long addr,
 
 	if ((type & MAP_FIXED_NOREPLACE) &&
 	    PTR_ERR((void *)map_addr) == -EEXIST)
-		pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
-			task_pid_nr(current), current->comm, (void *)addr);
+		pr_info("%d (%s): Uhuuh, elf segment at %lx requested but the memory is mapped already\n",
+			task_pid_nr(current), current->comm, addr);
 
 	return(map_addr);
 }

Re: [PATCH] elf: don't hash userspace addresses

[Tetsuo Handa]

Alexey Dobriyan wrote:
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---
> 
>  fs/binfmt_elf.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -379,8 +379,8 @@ static unsigned long elf_map(struct file *filep, unsigned long addr,
>  
>  	if ((type & MAP_FIXED_NOREPLACE) &&
>  	    PTR_ERR((void *)map_addr) == -EEXIST)
> -		pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
> -			task_pid_nr(current), current->comm, (void *)addr);
> +		pr_info("%d (%s): Uhuuh, elf segment at %lx requested but the memory is mapped already\n",
> +			task_pid_nr(current), current->comm, addr);

"%px" does not hash. For what reason you replace %px with %lx ?

>  
>  	return(map_addr);
>  }
> 

Re: [PATCH] elf: don't hash userspace addresses

[Alexey Dobriyan]

On Sat, May 05, 2018 at 09:31:50AM +0900, Tetsuo Handa wrote:
> Alexey Dobriyan wrote:
> > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> > ---
> > 
> >  fs/binfmt_elf.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > --- a/fs/binfmt_elf.c
> > +++ b/fs/binfmt_elf.c
> > @@ -379,8 +379,8 @@ static unsigned long elf_map(struct file *filep, unsigned long addr,
> >  
> >  	if ((type & MAP_FIXED_NOREPLACE) &&
> >  	    PTR_ERR((void *)map_addr) == -EEXIST)
> > -		pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
> > -			task_pid_nr(current), current->comm, (void *)addr);
> > +		pr_info("%d (%s): Uhuuh, elf segment at %lx requested but the memory is mapped already\n",
> > +			task_pid_nr(current), current->comm, addr);
> 
> "%px" does not hash. For what reason you replace %px with %lx ?

Duh. There is no reason to use non-standard %px.

Re: [PATCH] elf: don't hash userspace addresses

[Tetsuo Handa]

Alexey Dobriyan wrote:
> On Sat, May 05, 2018 at 09:31:50AM +0900, Tetsuo Handa wrote:
> > Alexey Dobriyan wrote:
> > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> > > ---
> > > 
> > >  fs/binfmt_elf.c |    4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > --- a/fs/binfmt_elf.c
> > > +++ b/fs/binfmt_elf.c
> > > @@ -379,8 +379,8 @@ static unsigned long elf_map(struct file *filep, unsigned long addr,
> > >  
> > >  	if ((type & MAP_FIXED_NOREPLACE) &&
> > >  	    PTR_ERR((void *)map_addr) == -EEXIST)
> > > -		pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
> > > -			task_pid_nr(current), current->comm, (void *)addr);
> > > +		pr_info("%d (%s): Uhuuh, elf segment at %lx requested but the memory is mapped already\n",
> > > +			task_pid_nr(current), current->comm, addr);
> > 
> > "%px" does not hash. For what reason you replace %px with %lx ?
> 
> Duh. There is no reason to use non-standard %px.
> 

See the comment for pointer() function in lib/vsprintf.c .
In Linux kernel world, various extension for %p is supported.

Re: [PATCH] elf: don't hash userspace addresses

[Alexey Dobriyan]

On Sat, May 05, 2018 at 10:19:43PM +0900, Tetsuo Handa wrote:
> Alexey Dobriyan wrote:
> > On Sat, May 05, 2018 at 09:31:50AM +0900, Tetsuo Handa wrote:
> > > Alexey Dobriyan wrote:
> > > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> > > > ---
> > > > 
> > > >  fs/binfmt_elf.c |    4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > 
> > > > --- a/fs/binfmt_elf.c
> > > > +++ b/fs/binfmt_elf.c
> > > > @@ -379,8 +379,8 @@ static unsigned long elf_map(struct file *filep, unsigned long addr,
> > > >  
> > > >  	if ((type & MAP_FIXED_NOREPLACE) &&
> > > >  	    PTR_ERR((void *)map_addr) == -EEXIST)
> > > > -		pr_info("%d (%s): Uhuuh, elf segment at %px requested but the memory is mapped already\n",
> > > > -			task_pid_nr(current), current->comm, (void *)addr);
> > > > +		pr_info("%d (%s): Uhuuh, elf segment at %lx requested but the memory is mapped already\n",
> > > > +			task_pid_nr(current), current->comm, addr);
> > > 
> > > "%px" does not hash. For what reason you replace %px with %lx ?
> > 
> > Duh. There is no reason to use non-standard %px.
> > 
> 
> See the comment for pointer() function in lib/vsprintf.c .
> In Linux kernel world, various extension for %p is supported.

%p has this funny property: scanf(printf("%p", ptr)) does not equal %p
because small pointer will become (null) or (errptr) or whatever is
decided in recent vsnprintf thread, therefore the less %p is used
the better.