[PATCH] Fix unsigned overflow in minsyms reader.

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[PATCH] Fix unsigned overflow in minsyms reader.

John Baldwin
Use a ssize_t helper variable for the number of bytes to shrink the
msymbols obstack rather than relying on unsigned overflow to shrink
the size of the obstack.

gdb/ChangeLog:

        * minsyms.c (minimal_symbol_reader::install): Fix unsigned
        overflow.
---
 gdb/ChangeLog | 5 +++++
 gdb/minsyms.c | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 68ecef7728..4120c62f33 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2018-11-06  John Baldwin  <[hidden email]>
+
+ * minsyms.c (minimal_symbol_reader::install): Fix unsigned
+ overflow.
+
 2018-11-06  John Baldwin  <[hidden email]>
 
  * riscv-fbsd-nat.c (getregs_supplies): Return true for
diff --git a/gdb/minsyms.c b/gdb/minsyms.c
index 4409e6f8b3..0f854422e0 100644
--- a/gdb/minsyms.c
+++ b/gdb/minsyms.c
@@ -1375,8 +1375,9 @@ minimal_symbol_reader::install ()
 
       mcount = compact_minimal_symbols (msymbols, mcount, m_objfile);
 
-      obstack_blank_fast (&m_objfile->per_bfd->storage_obstack,
-       (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol));
+      ssize_t shrink_bytes
+ = (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol);
+      obstack_blank_fast (&m_objfile->per_bfd->storage_obstack, shrink_bytes);
       msymbols = (struct minimal_symbol *)
  obstack_finish (&m_objfile->per_bfd->storage_obstack);
 
--
2.18.0

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Re: [PATCH] Fix unsigned overflow in minsyms reader.

Kevin Buettner
On Tue,  6 Nov 2018 11:04:23 -0800
John Baldwin <[hidden email]> wrote:

> Use a ssize_t helper variable for the number of bytes to shrink the
> msymbols obstack rather than relying on unsigned overflow to shrink
> the size of the obstack.
>
> gdb/ChangeLog:
>
> * minsyms.c (minimal_symbol_reader::install): Fix unsigned
> overflow.

Okay.

Kevin