Re: Question re: commit 2db20b97f1dc3e5dce3d6ed74a8a62f0dede8c80

Re: Question re: commit 2db20b97f1dc3e5dce3d6ed74a8a62f0dede8c80

[Alan Modra]

On Sat, Aug 12, 2023 at 09:28:30AM -0700, Keith Seitz wrote:
> Hi,
> 
> I see this was just committed to binutils-gdb:
> 
> commit 2db20b97f1dc3e5dce3d6ed74a8a62f0dede8c80
> Author: Alan Modra <amodra@gmail.com>
> Date:   Wed Aug 9 09:58:36 2023 +0930
> 
>     gdb: warn unused result for bfd IO functions
>     This fixes the compilation warnings introduced by my bfdio.c patch.
> 
> This commit contains this hunk:
> 
> @@ -374,12 +395,13 @@ read_pe_exported_syms (minimal_symbol_reader &reader,
>      {
>        char sname[8];
>        unsigned long secptr1 = secptr + 40 * i;
> -      unsigned long vaddr = pe_get32 (dll, secptr1 + 12);
> -      unsigned long vsize = pe_get32 (dll, secptr1 + 16);
> -      unsigned long fptr = pe_get32 (dll, secptr1 + 20);
> +      unsigned long vaddr = pe_get32 (dll, secptr1 + 12, &fail);
> +      unsigned long vsize = pe_get32 (dll, secptr1 + 16, &fail);
> +      unsigned long fptr = pe_get32 (dll, secptr1 + 20, &fail);
> -      bfd_seek (dll, (file_ptr) secptr1, SEEK_SET);
> -      bfd_read (sname, (bfd_size_type) sizeof (sname), dll);
> +      if (fail
> +         || bfd_seek (dll, secptr1, SEEK_SET) != 0
> +         || bfd_read (sname, sizeof (sname), dll) != sizeof (sname))
>        if ((strcmp (sname, ".edata") == 0)
>           || (vaddr <= export_opthdrrva && export_opthdrrva < vaddr + vsize))
> 
> Maybe I'm just really out of touch, but can you explain that "if (fail\n|| bfd_seek..." block?
> It looks like it is missing a statement?

Indeed it is.  I don't know how that happened, but it wasn't Andrew's
update to my patch.  I'm committing the following as obvious.

diff --git a/gdb/coff-pe-read.c b/gdb/coff-pe-read.c
index 0d76ebdbfce..56137ac4dd0 100644
--- a/gdb/coff-pe-read.c
+++ b/gdb/coff-pe-read.c
@@ -402,6 +402,7 @@ read_pe_exported_syms (minimal_symbol_reader &reader,
       if (fail
 	  || bfd_seek (dll, secptr1, SEEK_SET) != 0
 	  || bfd_read (sname, sizeof (sname), dll) != sizeof (sname))
+	return maybe_print_debug_msg ();
 
       if ((strcmp (sname, ".edata") == 0)
 	  || (vaddr <= export_opthdrrva && export_opthdrrva < vaddr + vsize))

> [I am hacking coff-pe-read.c to fix some CVEs that were filed against it.]
> 
> Keith

-- 
Alan Modra
Australia Development Lab, IBM