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-rw-r--r--shell/ash.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/shell/ash.c b/shell/ash.c
index 789a81c..790367b 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -11659,9 +11659,18 @@ parsebackq: {
str = NULL;
savelen = out - (char *)stackblock();
if (savelen > 0) {
+ /*
+ * FIXME: this can allocate very large block on stack and SEGV.
+ * Example:
+ * echo "..<100kbytes>..`true` $(true) `true` ..."
+ * alocates 100kb for every command subst. With about
+ * a hundred command substitutions stack overflows.
+ * With larger prepended string, SEGV happens sooner.
+ */
str = alloca(savelen);
memcpy(str, stackblock(), savelen);
}
+
if (oldstyle) {
/* We must read until the closing backquote, giving special
* treatment to some slashes, and then push the string and