Protect malloc, realloc and free calls with INT{ON,OFF} directly in chkalloc,

ckrealloc and ckfree (added), respectively.  sh jumps out of the signal handler
using longjmp which is obviously a bad idea during malloc calls.

Note: I think there is still a small race here because volatile sig_atomic_t
only guarantees atomic reads and writes while we're doing increments and
decrements.

Protect a setmode call with INT{ON,OFF} as it calls malloc internally.

PR:		45478
Patch from:	Nate Eldredge

1 files changed, 16 insertions, 2 deletions

diff --git a/bin/sh/memalloc.c b/bin/sh/memalloc.c
index 60f9203..115eea0 100644
--- a/bin/sh/memalloc.c
+++ b/bin/sh/memalloc.c
@@ -57,7 +57,10 @@ ckmalloc(int nbytes)
 {
 	pointer p;
 
-	if ((p = malloc(nbytes)) == NULL)
+	INTOFF;
+	p = malloc(nbytes);
+	INTON;
+	if (p == NULL)
 		error("Out of space");
 	return p;
 }
@@ -70,11 +73,22 @@ ckmalloc(int nbytes)
 pointer
 ckrealloc(pointer p, int nbytes)
 {
-	if ((p = realloc(p, nbytes)) == NULL)
+	INTOFF;
+	p = realloc(p, nbytes);
+	INTON;
+	if (p == NULL)
 		error("Out of space");
 	return p;
 }
 
+void
+ckfree(pointer p)
+{
+	INTOFF;
+	free(p);
+	INTON;
+}
+
 
 /*
  * Make a copy of a string in safe storage.