patch 9.2.0278: viminfo: heap buffer overflow when reading viminfo file

Problem:  Reading a crafted viminfo file can cause a heap buffer
          overflow because the length value from getdigits() is cast to
          int, truncating large size_t values
Solution: Remove the (int) cast when calling alloc() (sentinel404)

Signed-off-by: Christian Brabandt <cb@256bit.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/testdir/test_viminfo.vim b/src/testdir/test_viminfo.vim
index ff79265f8e..b3a8b91cb1 100644
--- a/src/testdir/test_viminfo.vim
+++ b/src/testdir/test_viminfo.vim
@@ -1371,4 +1371,24 @@ func Test_viminfo_len_one()
   let &viminfofile = _viminfofile
 endfunc
 
+func Test_viminfo_len_overflow()
+  let _viminfofile = &viminfofile
+  let &viminfofile=''
+  let viminfo_file = tempname()
+  defer delete(viminfo_file)
+
+  " Craft a viminfo entry with size_t length overflow
+  call writefile(['# Viminfo',
+        \ '|1,4', '|2,>4294967311',
+        \ '|<"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA',
+        \ '|<BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB',
+        \ '|<CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC',
+        \ '|<DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD'], viminfo_file, 'b')
+
+  " Should not crash or cause memory errors
+  exe 'rviminfo! ' .. viminfo_file
+
+  let &viminfofile = _viminfofile
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab