Author: jilles
Date: Sat Mar 4 22:58:34 2017
New Revision: 314686
URL: https://svnweb.freebsd.org/changeset/base/314686
Log:
sh: Fix crash if a -T trap is taken during command substitution.
Code like t=$(stat -f %m "$file") segfaulted if -T was active and a trap
was taken while the shell was waiting for the child process to finish.
What happened was that the dotrap() call in waitforjob() was hit. This
re-entered command execution (including expand.c) at a point not expected by
expbackq(), and global state (unallocated stack string and argbackq) was
corrupted.
To fix this, change expbackq() to prepare for command execution to be
re-entered.
Reported by: bdrewery
MFC after: 1 week
Added:
head/bin/sh/tests/expansion/cmdsubst21.0 (contents, props changed)
head/bin/sh/tests/expansion/cmdsubst22.0 (contents, props changed)
Modified:
head/bin/sh/expand.c
head/bin/sh/tests/expansion/Makefile
Modified: head/bin/sh/expand.c
==============================================================================
--- head/bin/sh/expand.c Sat Mar 4 22:38:10 2017 (r314685)
+++ head/bin/sh/expand.c Sat Mar 4 22:58:34 2017 (r314686)
@@ -460,7 +460,6 @@ expbackq(union node *cmd, int quoted, in
p = grabstackstr(dest);
evalbackcmd(cmd, &in);
ungrabstackstr(p, dest);
- argbackq = saveargbackq;
p = in.buf;
nnl = 0;
@@ -514,12 +513,16 @@ expbackq(union node *cmd, int quoted, in
close(in.fd);
if (in.buf)
ckfree(in.buf);
- if (in.jp)
+ if (in.jp) {
+ p = grabstackstr(dest);
exitstatus = waitforjob(in.jp, (int *)NULL);
+ ungrabstackstr(p, dest);
+ }
TRACE(("expbackq: size=%td: \"%.*s\"\n",
((dest - stackblock()) - startloc),
(int)((dest - stackblock()) - startloc),
stackblock() + startloc));
+ argbackq = saveargbackq;
expdest = dest;
INTON;
}
Modified: head/bin/sh/tests/expansion/Makefile
==============================================================================
--- head/bin/sh/tests/expansion/Makefile Sat Mar 4 22:38:10 2017
(r314685)
+++ head/bin/sh/tests/expansion/Makefile Sat Mar 4 22:58:34 2017
(r314686)
@@ -42,6 +42,8 @@ ${PACKAGE}FILES+= cmdsubst17.0
${PACKAGE}FILES+= cmdsubst18.0
${PACKAGE}FILES+= cmdsubst19.0
${PACKAGE}FILES+= cmdsubst20.0
+${PACKAGE}FILES+= cmdsubst21.0
+${PACKAGE}FILES+= cmdsubst22.0
${PACKAGE}FILES+= export1.0
${PACKAGE}FILES+= export2.0
${PACKAGE}FILES+= export3.0
Added: head/bin/sh/tests/expansion/cmdsubst21.0
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/bin/sh/tests/expansion/cmdsubst21.0 Sat Mar 4 22:58:34 2017
(r314686)
@@ -0,0 +1,6 @@
+# $FreeBSD$
+
+set -T
+trapped=''
+trap "trapped=x$trapped" TERM
+[ "x$($SH -c "kill $$")y" = xy ] && [ "$trapped" = x ]
Added: head/bin/sh/tests/expansion/cmdsubst22.0
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/bin/sh/tests/expansion/cmdsubst22.0 Sat Mar 4 22:58:34 2017
(r314686)
@@ -0,0 +1,6 @@
+# $FreeBSD$
+
+set -T
+trapped=''
+trap "trapped=x$trapped" TERM
+[ "x$(:; kill $$)y" = xy ] && [ "$trapped" = x ]
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