Commit: patch 9.0.2158: [security]: use-after-free in check_argument_type

[Christian Brabandt]

patch 9.0.2158: [security]: use-after-free in check_argument_type

Commit: https://github.com/vim/vim/commit/0f28791b215bd4c22ed580839409c2f7d39d8140
Author: Christian Brabandt <c...@256bit.org>
Date: Mon Dec 11 17:53:25 2023 +0100

patch 9.0.2158: [security]: use-after-free in check_argument_type

Problem: [security]: use-after-free in check_argument_type
Solution: Reset function type pointer when freeing the function type
list

function pointer fp->uf_func_type may point to the same memory, that was
allocated for fp->uf_type_list. However, when cleaning up a function
definition (e.g. because it was invalid), fp->uf_type_list will be
freed, but fp->uf_func_type may still point to the same (now) invalid
memory address.

So when freeing the fp->uf_type_list, check if fp->func_type points to
any of those types and if it does, reset the fp->uf_func_type pointer to
the t_func_any (default) type pointer

closes: #13652

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

diff --git a/src/proto/vim9type.pro b/src/proto/vim9type.pro
index 85cc96fb2..1643e0c0f 100644
--- a/src/proto/vim9type.pro
+++ b/src/proto/vim9type.pro
@@ -2,6 +2,7 @@
type_T *get_type_ptr(garray_T *type_gap);
type_T *copy_type(type_T *type, garray_T *type_gap);
void clear_type_list(garray_T *gap);
+void clear_func_type_list(garray_T *gap, type_T **func_type);
type_T *alloc_type(type_T *type);
void free_type(type_T *type);
void set_tv_type(typval_T *tv, type_T *type);
diff --git a/src/testdir/crash/poc_uaf_check_argument_types b/src/testdir/crash/poc_uaf_check_argument_types
new file mode 100644
index 0000000000000000000000000000000000000000..83a2e7b0a69305a319dde36451416092f5153ef2
GIT binary patch
literal 43
ycmYdEO;ZTcNVDbAWZ+88OG!yh<0{sVQB~K}kFgEX(BvvB<}xTwF5)WAX8-{DR|{DH

literal 0
HcmV?d00001

diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index 242da8e5d..fd786e5d5 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -184,6 +184,12 @@ func Test_crash1_3()
call term_sendkeys(buf, args)
call TermWait(buf, 150)

+ let file = 'crash/poc_uaf_check_argument_types'
+ let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+ let args = printf(cmn_args, vim, file)
+ call term_sendkeys(buf, args)
+ call TermWait(buf, 150)
+
" clean up
exe buf .. "bw!"
bw!
diff --git a/src/userfunc.c b/src/userfunc.c
index e2b1bc322..410658b1e 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -2533,7 +2533,7 @@ func_clear_items(ufunc_T *fp)
VIM_CLEAR(fp->uf_arg_types);
VIM_CLEAR(fp->uf_block_ids);
VIM_CLEAR(fp->uf_va_name);
- clear_type_list(&fp->uf_type_list);
+ clear_func_type_list(&fp->uf_type_list, &fp->uf_func_type);

// Increment the refcount of this function to avoid it being freed
// recursively when the partial is freed.
@@ -5435,7 +5435,7 @@ errret_2:
{
VIM_CLEAR(fp->uf_arg_types);
VIM_CLEAR(fp->uf_va_name);
- clear_type_list(&fp->uf_type_list);
+ clear_func_type_list(&fp->uf_type_list, &fp->uf_func_type);
}
if (free_fp)
VIM_CLEAR(fp);
diff --git a/src/version.c b/src/version.c
index 919f42f2d..4bb1c90ba 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 2158,
/**/
2157,
/**/
diff --git a/src/vim9type.c b/src/vim9type.c
index a142a7b9c..fec2bf9d3 100644
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -122,6 +122,19 @@ clear_type_list(garray_T *gap)
ga_clear(gap);
}

+ void
+clear_func_type_list(garray_T *gap, type_T **func_type)
+{
+ while (gap->ga_len > 0)
+ {
+ // func_type pointing to the uf_type_list, so reset pointer
+ if (*func_type == ((type_T **)gap->ga_data)[--gap->ga_len])
+ *func_type = &t_func_any;
+ vim_free(((type_T **)gap->ga_data)[gap->ga_len]);
+ }
+ ga_clear(gap);
+}
+
/*
* Take a type that is using entries in a growarray and turn it into a type
* with allocated entries.