https://sourceware.org/bugzilla/show_bug.cgi?id=24075
Mark Wielaard <mark at klomp dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
CC| |mark at klomp dot org
Resolution|--- |FIXED
Summary|Program Crash due to Wild |Program Crash due to buffer
|pointer Deference in |over-read in
|ebl_object_note function in |ebl_object_note function in
|eblobjnote.c in libebl. |eblobjnote.c in libebl.
--- Comment #3 from Mark Wielaard <mark at klomp dot org> ---
(In reply to wcventure from comment #0)
> Our fuzzer caught Pointer Deference problem in eu-readelf of the latest
> elfutils-0.174 code base, this inputs will cause the segment faults and I
> have confirmed them with address sanitizer too. Please use the "./eu-readelf
> -a $POC"to reproduce the bug. If you have any questions, please let me know.
This code was introduced in 0.175 and not present in 0.174.
Confirmed by running the reproducer under valgrind.
> This problem is in the code as fllow, it seem like a use-after-fee problem.
>
> > size_t i;
> > for (i = 0; i < prop.pr_datasz - 1; i++)
> > printf ("%02" PRIx8 " ", (uint8_t) desc[i]);
Yes, this over-reads the buffer because pr_datasz isn't checked.
Fixed as follows:
commit 012018907ca05eb0ab51d424a596ef38fc87cae1
Author: Mark Wielaard <[email protected]>
Date: Wed Jan 16 11:57:35 2019 +0100
libebl: Check GNU property note pr_datasz fits inside note description.
Before printing the data values, make sure pr_datasz doesn't go beyond
the end of the note description data.
https://sourceware.org/bugzilla/show_bug.cgi?id=24075
Signed-off-by: Mark Wielaard <[email protected]>
diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index 0174f33..77c2274 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,7 @@
+2019-01-16 Mark Wielaard <[email protected]>
+
+ * eblobjnte.c (ebl_object_note): Check pr_datasz isn't too large.
+
2018-12-02 Mark Wielaard <[email protected]>
* eblobjnte.c (ebl_object_note): For GNU_PROPERTY_STACK_SIZE use
diff --git a/libebl/eblobjnote.c b/libebl/eblobjnote.c
index c19ea37..9094715 100644
--- a/libebl/eblobjnote.c
+++ b/libebl/eblobjnote.c
@@ -350,6 +350,13 @@ ebl_object_note (Ebl *ebl, uint32_t namesz, const char
*name, uint32_t type,
desc += 8;
descsz -= 8;
+ if (prop.pr_datasz > descsz)
+ {
+ printf ("BAD property datasz: %" PRId32 "\n",
+ prop.pr_datasz);
+ return;
+ }
+
int elfclass = gelf_getclass (ebl->elf);
char *elfident = elf_getident (ebl->elf, NULL);
GElf_Ehdr ehdr;
--
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