[gentoo-commits] proj/sandbox:master commit in: libsandbox/

[Mike Frysinger]

commit:     a374b1f829a07cce3eb708f078a2a70f9bc4d975
Author:     Mike Frysinger <vapier <AT> gentoo <DOT> org>
AuthorDate: Thu Oct 28 05:49:33 2021 +0000
Commit:     Mike Frysinger <vapier <AT> gentoo <DOT> org>
CommitDate: Thu Oct 28 05:49:33 2021 +0000
URL:        https://gitweb.gentoo.org/proj/sandbox.git/commit/?id=a374b1f8

libsandbox: fix signal pass through with ptrace main loop

When we're notified that the child has received a signal, we need to
pass it through since we don't care about signals.  We did that, but
using PTRACE_CONT which causes the process to just resume, and then
we'd call PTRACE_SYSCALL on that resumed state.  When the pass thru
logic was a signal handler, PTRACE_CONT was correct since it would
come in while in the middle of PTRACE_SYSCALL, but after the rewrite
of the main loop, it's now the wrong call.  Pass the signal back to
the existing PTRACE_SYSCALL call so that we stay in the main loop
and get notified on the next syscall event.

Closes: https://bugs.gentoo.org/820407
Signed-off-by: Mike Frysinger <vapier <AT> gentoo.org>

 libsandbox/trace.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libsandbox/trace.c b/libsandbox/trace.c
index b7e65b4..d53051d 100644
--- a/libsandbox/trace.c
+++ b/libsandbox/trace.c
@@ -405,13 +405,16 @@ static void trace_loop(void)
 	long ret;
 	int status, sig;
 	const struct syscall_entry *tbl_after_fork;
+	void *data;
 
 	before_exec = true;
 	before_syscall = false;
 	fake_syscall_ret = false;
 	tbl_after_fork = NULL;
+	data = NULL;
 	do {
-		ret = do_ptrace(PTRACE_SYSCALL, NULL, NULL);
+		ret = do_ptrace(PTRACE_SYSCALL, NULL, data);
+		data = NULL;
 		waitpid(trace_pid, &status, 0);
 
 		event = (unsigned)status >> 16;
@@ -444,7 +447,7 @@ static void trace_loop(void)
 				 * and we'll exit then.
 				 */
 				sb_debug("passing signal through %s (%i)", strsig(sig), sig);
-				do_ptrace(PTRACE_CONT, NULL, (void *)(uintptr_t)(sig));
+				data = (void *)(uintptr_t)(sig);
 				continue;
 			}