From: Alan Modra <amodra@gmail.com>
To: binutils@sourceware.org
Subject: bus error with fuzzed archive element
Date: Sat, 4 May 2024 20:26:39 +0930 [thread overview]
Message-ID: <ZjYUZ0yTjLmFGitF@squeak.grove.modra.org> (raw)
* libbfd.c (bfd_mmap_local): Sanity check rsize against actual
file offset and size, not an archive element offset and size.
diff --git a/bfd/libbfd.c b/bfd/libbfd.c
index 747b69ec2c6..53868471001 100644
--- a/bfd/libbfd.c
+++ b/bfd/libbfd.c
@@ -1072,7 +1072,18 @@ static void *
bfd_mmap_local (bfd *abfd, size_t rsize, int prot, void **map_addr,
size_t *map_size)
{
- ufile_ptr filesize = bfd_get_file_size (abfd);
+ /* We mmap on the underlying file. In an archive it might be nice
+ to limit RSIZE to the element size, but that can be fuzzed and
+ the offset returned by bfd_tell is relative to the start of the
+ element. Therefore to reliably stop access beyond the end of a
+ file (and resulting bus errors) we must work with the underlying
+ file offset and size, and trust that callers will limit access to
+ within an archive element. */
+ while (abfd->my_archive != NULL
+ && !bfd_is_thin_archive (abfd->my_archive))
+ abfd = abfd->my_archive;
+
+ ufile_ptr filesize = bfd_get_size (abfd);
ufile_ptr offset = bfd_tell (abfd);
if (filesize < offset || filesize - offset < rsize)
{
--
Alan Modra
reply other threads:[~2024-05-04 10:56 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZjYUZ0yTjLmFGitF@squeak.grove.modra.org \
--to=amodra@gmail.com \
--cc=binutils@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).