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 <evv...@ya.ru>
Signed-off-by: Mark Wielaard <m...@klomp.org>
---
libdwfl/ChangeLog | 5 +++++
libdwfl/dwfl_segment_report_module.c | 3 +++
2 files changed, 8 insertions(+)
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 856bd335..aaea164c 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,8 @@
+2021-12-12 Mark Wielaard <m...@klomp.org>
+
+ * dwfl_segment_report_module.c (dwfl_segment_report_module): Don't
+ allocate more than SIZE_MAX.
+
2021-12-09 Mark Wielaard <m...@klomp.org>
* link_map.c (dwfl_link_map_report): Limit dyn_filesz malloc size
diff --git a/libdwfl/dwfl_segment_report_module.c
b/libdwfl/dwfl_segment_report_module.c
index f4acfe53..46564ec5 100644
--- a/libdwfl/dwfl_segment_report_module.c
+++ b/libdwfl/dwfl_segment_report_module.c
@@ -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;
--
2.30.2
