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Re: [committed, PATCH] Check file size before getting section contents
On Mon, Jun 26, 2017 at 3:53 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Jun 26, 2017 at 3:24 PM, Pedro Alves <palves@redhat.com> wrote:
>> On 06/26/2017 10:48 PM, Pedro Alves wrote:
>>> Hi H.J.,
>>>
>>> This patch caused many regressions in GDB's testsuite:
>>>
>>> https://sourceware.org/ml/gdb-testers/2017-q2/msg05045.html
>>>
>>> x86 buildslaves haven't caught up with the patch yet, but I
>>> see the same thing locally, on my x86-64 machine. (git bisect
>>> pointed me here.)
>>>
>>> Here's quick way to run only a few of the tests that are now failing:
>>>
>>> $ make check TESTS="gdb.base/break-interp.exp gdb.base/corefile.exp gdb.base/solib-search.exp gdb.reverse/sigall-precsave.exp"
>>>
>>> Any idea what's going on?
>>>
>>> BTW, this looks very suspicious:
>>>
>>> @@ -867,7 +876,13 @@ _bfd_generic_get_section_contents_in_window
>>> sz = section->rawsize;
>>> else
>>> sz = section->size;
>>> + filesz = bfd_get_file_size (abfd);
>>> + {
>>> + /* This should never happen. */
>>> + abort ();
>>> + }
>>>
>>> ... because that abort is unconditional. Did you intend
>>> to guard it with:
>>> if (filesz < 0)
>>> like in _bfd_generic_get_section_contents?
>>>
>>
>>> @@ -811,8 +812,15 @@ _bfd_generic_get_section_contents (bfd *abfd,
>>> sz = section->rawsize;
>>> else
>>> sz = section->size;
>>> + filesz = bfd_get_file_size (abfd);
>>> + if (filesz < 0)
>>> + {
>>> + /* This should never happen. */
>>> + abort ();
>>> + }
>>> if (offset + count < count
>>> - || offset + count > sz)
>>> + || offset + count > sz
>>> + || (section->filepos + offset + sz) > (bfd_size_type) filesz)
>>> {
>>
>> The problem is this new "section->filepos + offset + sz"
>> check here. GDB calls bfd_get_section_contents with offset != 0,
>> which causes that "offset + sz" addition to shoot past filesz.
>> I can't see how that new check makes sense as is. We're reading
>> "count" bytes, not "sz" bytes.
>
> Please try this:
>
> diff --git a/bfd/libbfd.c b/bfd/libbfd.c
> index 7b270ef..8bad4ab 100644
> --- a/bfd/libbfd.c
> +++ b/bfd/libbfd.c
> @@ -820,7 +820,7 @@ _bfd_generic_get_section_contents (bfd *abfd,
> }
> if (offset + count < count
> || offset + count > sz
> - || (section->filepos + offset + sz) > (bfd_size_type) filesz)
> + || (section->filepos + sz) > (bfd_size_type) filesz)
> {
> bfd_set_error (bfd_error_invalid_operation);
> return FALSE;
> @@ -883,7 +883,7 @@ _bfd_generic_get_section_contents_in_window
> abort ();
> }
> if (offset + count > sz
> - || (section->filepos + offset + sz) > (bfd_size_type) filesz
> + || (section->filepos + sz) > (bfd_size_type) filesz
> || ! bfd_get_file_window (abfd, section->filepos + offset, count, w,
> TRUE))
> return FALSE;
>
With changelog.
--
H.J.
From 023539992080d3c20053ecb768a8869a4db3d635 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 26 Jun 2017 16:08:15 -0700
Subject: [PATCH] Properly check section size in
_bfd_generic_get_section_contents
Check
(section->filepos + sz) > file size
instead of
(section->filepos + offset + sz) > file size
* libbfd.c (_bfd_generic_get_section_contents): Don't add
section offset when checking section size agains file size.
(_bfd_generic_get_section_contents_in_window): Likewise.
---
bfd/libbfd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/bfd/libbfd.c b/bfd/libbfd.c
index 7b270ef..8bad4ab 100644
--- a/bfd/libbfd.c
+++ b/bfd/libbfd.c
@@ -820,7 +820,7 @@ _bfd_generic_get_section_contents (bfd *abfd,
}
if (offset + count < count
|| offset + count > sz
- || (section->filepos + offset + sz) > (bfd_size_type) filesz)
+ || (section->filepos + sz) > (bfd_size_type) filesz)
{
bfd_set_error (bfd_error_invalid_operation);
return FALSE;
@@ -883,7 +883,7 @@ _bfd_generic_get_section_contents_in_window
abort ();
}
if (offset + count > sz
- || (section->filepos + offset + sz) > (bfd_size_type) filesz
+ || (section->filepos + sz) > (bfd_size_type) filesz
|| ! bfd_get_file_window (abfd, section->filepos + offset, count, w,
TRUE))
return FALSE;
--
2.9.4