[COMMITTED] libdwfl: Don't allocate more than SIZE_MAX in dwfl_segment_report_module.
Commit Message
The code in dwfl_segment_report_module tries to allocate and fill in
memory as described in a core file. Normally all memory in filled in
through the (phdrs) memory_callback or the read_eagerly callback. If
the last callback doesn't work we try to calloc file_trimmed_end bytes
and then try to fill in the parts of memory we can from the core file
at the correct offsets.
file_trimmed_end is a GElf_Off which is an unsigned 64bit type. On
32bit systems this means when cast to a size_t to do an allocation
might allocate truncated (much smaller) value. So make sure to not
allocate more than SIZE_MAX bytes.
It would be nice to have a better way to limit the amount of memory
allocated here. A core file might describe really big memory areas for
which it doesn't provide any data. In that case we really shouldn't
calloc mega- or giga-bytes of zeroed out memory.
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
libdwfl/ChangeLog | 5 +++++
libdwfl/dwfl_segment_report_module.c | 3 +++
2 files changed, 8 insertions(+)
@@ -1,3 +1,8 @@
+2021-12-12 Mark Wielaard <mark@klomp.org>
+
+ * dwfl_segment_report_module.c (dwfl_segment_report_module): Don't
+ allocate more than SIZE_MAX.
+
2021-12-09 Mark Wielaard <mark@klomp.org>
* link_map.c (dwfl_link_map_report): Limit dyn_filesz malloc size
@@ -904,6 +904,9 @@ dwfl_segment_report_module (Dwfl *dwfl, int ndx, const char *name,
/* The caller wants to read the whole file in right now, but hasn't
done it for us. Fill in a local image of the virtual file. */
+ if (file_trimmed_end > SIZE_MAX)
+ goto out;
+
void *contents = calloc (1, file_trimmed_end);
if (unlikely (contents == NULL))
goto out;