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patch 9.0.2149: [security]: use-after-free in exec_instructions()

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Problem:  [security]: use-after-free in exec_instructions()
Solution: get tv pointer again

[security]: use-after-free in exec_instructions()

exec_instructions may access freed memory, if the GA_GROWS_FAILS()
re-allocates memory. When this happens, the typval tv may still point to
now already freed memory. So let's get that pointer again and compare it
with tv. If those two pointers differ, tv is now invalid and we have to
refresh the tv pointer.

closes: #13621

Signed-off-by: Christian Brabandt <cb@256bit.org>
This commit is contained in:
Christian Brabandt
2023-12-04 22:52:23 +01:00
parent 1e5d66408e
commit 5dd41d4b63
4 changed files with 41 additions and 14 deletions
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14
src/vim9execute.c
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@@ -4123,8 +4123,22 @@ exec_instructions(ectx_T *ectx)
+ iptr->isn_arg.outer.outer_idx;
if (iptr->isn_type == ISN_LOADOUTER)
{
typval_T *copy;
if (GA_GROW_FAILS(&ectx->ec_stack, 1))
goto theend;
// careful: ga_grow_inner may re-alloc the stack
if (depth < 0)
copy = ((typval_T *)outer->out_loop[-depth - 1]
.stack->ga_data)
+ outer->out_loop[-depth - 1].var_idx
+ iptr->isn_arg.outer.outer_idx;
else
copy = ((typval_T *)outer->out_stack->ga_data)
+ outer->out_frame_idx + STACK_FRAME_SIZE
+ iptr->isn_arg.outer.outer_idx;
// memory was freed, get tv again
if (copy != tv)
tv = copy;
copy_tv(tv, STACK_TV_BOT(0));
++ectx->ec_stack.ga_len;
}