[PATCH] bfd_mmap_local: Check offset and size

[PATCH] bfd_mmap_local: Check offset and size

[H.J. Lu]

Update bfd_mmap_local to return NULL if offset + size > the file size.

	* libbfd.c (bfd_mmap_local): Validate offset and size against
	the file size.
---
 bfd/libbfd.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/bfd/libbfd.c b/bfd/libbfd.c
index 34197b75b5e..400a5a47d2a 100644
--- a/bfd/libbfd.c
+++ b/bfd/libbfd.c
@@ -1072,18 +1072,15 @@ static void *
 bfd_mmap_local (bfd *abfd, size_t rsize, int prot, void **map_addr,
 		size_t *map_size)
 {
-  if (!_bfd_constant_p (rsize))
+  ufile_ptr filesize = bfd_get_file_size (abfd);
+  ufile_ptr offset = bfd_tell (abfd);
+  if ((offset + rsize) > filesize)
     {
-      ufile_ptr filesize = bfd_get_file_size (abfd);
-      if (filesize != 0 && rsize > filesize)
-	{
-	  bfd_set_error (bfd_error_file_truncated);
-	  return NULL;
-	}
+      bfd_set_error (bfd_error_file_truncated);
+      return NULL;
     }
 
   void *mem;
-  ufile_ptr offset = bfd_tell (abfd);
   mem = bfd_mmap (abfd, NULL, rsize, prot, MAP_PRIVATE, offset,
 		  map_addr, map_size);
   return mem;
-- 
2.44.0

Re: [PATCH] bfd_mmap_local: Check offset and size

[Alan Modra]

On Wed, Apr 03, 2024 at 06:34:33PM -0700, H.J. Lu wrote:
> Update bfd_mmap_local to return NULL if offset + size > the file size.
> 
> 	* libbfd.c (bfd_mmap_local): Validate offset and size against
> 	the file size.
> ---
>  bfd/libbfd.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/bfd/libbfd.c b/bfd/libbfd.c
> index 34197b75b5e..400a5a47d2a 100644
> --- a/bfd/libbfd.c
> +++ b/bfd/libbfd.c
> @@ -1072,18 +1072,15 @@ static void *
>  bfd_mmap_local (bfd *abfd, size_t rsize, int prot, void **map_addr,
>  		size_t *map_size)
>  {
> -  if (!_bfd_constant_p (rsize))
> +  ufile_ptr filesize = bfd_get_file_size (abfd);
> +  ufile_ptr offset = bfd_tell (abfd);
> +  if ((offset + rsize) > filesize)

Doesn't need parens around "offset + rsize" here.  Also, can this
expression ever overflow?  If so it would be better written as

  if (filesize < offset
      || filesize - offset < rsize)

>      {
> -      ufile_ptr filesize = bfd_get_file_size (abfd);
> -      if (filesize != 0 && rsize > filesize)
> -	{
> -	  bfd_set_error (bfd_error_file_truncated);
> -	  return NULL;
> -	}
> +      bfd_set_error (bfd_error_file_truncated);
> +      return NULL;
>      }
>  
>    void *mem;
> -  ufile_ptr offset = bfd_tell (abfd);
>    mem = bfd_mmap (abfd, NULL, rsize, prot, MAP_PRIVATE, offset,
>  		  map_addr, map_size);
>    return mem;
> -- 
> 2.44.0

-- 
Alan Modra
Australia Development Lab, IBM

Re: [PATCH] bfd_mmap_local: Check offset and size

[H.J. Lu]

On Thu, Apr 4, 2024 at 12:20 AM Alan Modra <amodra@gmail.com> wrote:
>
> On Wed, Apr 03, 2024 at 06:34:33PM -0700, H.J. Lu wrote:
> > Update bfd_mmap_local to return NULL if offset + size > the file size.
> >
> >       * libbfd.c (bfd_mmap_local): Validate offset and size against
> >       the file size.
> > ---
> >  bfd/libbfd.c | 13 +++++--------
> >  1 file changed, 5 insertions(+), 8 deletions(-)
> >
> > diff --git a/bfd/libbfd.c b/bfd/libbfd.c
> > index 34197b75b5e..400a5a47d2a 100644
> > --- a/bfd/libbfd.c
> > +++ b/bfd/libbfd.c
> > @@ -1072,18 +1072,15 @@ static void *
> >  bfd_mmap_local (bfd *abfd, size_t rsize, int prot, void **map_addr,
> >               size_t *map_size)
> >  {
> > -  if (!_bfd_constant_p (rsize))
> > +  ufile_ptr filesize = bfd_get_file_size (abfd);
> > +  ufile_ptr offset = bfd_tell (abfd);
> > +  if ((offset + rsize) > filesize)
>
> Doesn't need parens around "offset + rsize" here.  Also, can this
> expression ever overflow?  If so it would be better written as
>
>   if (filesize < offset
>       || filesize - offset < rsize)

The v2 patch:

https://sourceware.org/pipermail/binutils/2024-April/133372.html

-- 
H.J.