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[PATCH] libelf: Sanity check offset and size before trying to malloc and read data.
- From: Mark Wielaard <mjw at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Fri, 21 Oct 2016 15:24:34 +0200
- Subject: [PATCH] libelf: Sanity check offset and size before trying to malloc and read data.
Bad sh_off or sh_size could trigger a bad malloc or read. Sanity check
the header values first before trying to malloc a huge buffer or reading
any data that will certainly fail.
https://bugzilla.redhat.com/show_bug.cgi?id=1387584
Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
libelf/ChangeLog | 5 +++++
libelf/elf_getdata.c | 11 +++++++++++
2 files changed, 16 insertions(+)
diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index 35af786..89546ab 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,8 @@
+2016-10-21 Mark Wielaard <mjw@redhat.com>
+
+ * elf_getdata.c (__libelf_set_rawdata_wrlock): Sanity check
+ offset and size before trying to malloc and read data.
+
2015-10-11 Akihiko Odaki <akihiko.odaki.4i@stu.hosei.ac.jp>
* elf_getarsym.c (elf_getarsym): Open code rawmemchr when not
diff --git a/libelf/elf_getdata.c b/libelf/elf_getdata.c
index d1fafbf..97c503b 100644
--- a/libelf/elf_getdata.c
+++ b/libelf/elf_getdata.c
@@ -312,6 +312,17 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
}
else if (likely (elf->fildes != -1))
{
+ /* First see whether the information in the section header is
+ valid and it does not ask for too much. Check for unsigned
+ overflow. */
+ if (unlikely (offset > elf->maximum_size
+ || elf->maximum_size - offset < size))
+ {
+ /* Something is wrong. */
+ __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
+ return 1;
+ }
+
/* We have to read the data from the file. Allocate the needed
memory. */
scn->rawdata_base = scn->rawdata.d.d_buf
--
1.8.3.1