From 1f3b01f625dd7d33a7107efbd8417857461bb4fe Mon Sep 17 00:00:00 2001 From: Markus Wichmann Date: Thu, 2 Nov 2023 17:39:33 +0100 Subject: [PATCH 4/4] Ensure valid setxid return value. If __synccall() fails to capture all threads because tkill fails for some reason other than EAGAIN, then the callback given will never be executed, so nothing will ever overwrite the initial value. So that is the value that will be returned from the function. The previous setting of 1 is not a valid value for setuid() et al. to return. I chose -EAGAIN since I don't know the reason the synccall failed ahead of time, but EAGAIN is a specified error code for a possibly temporary failure in setuid(). --- src/unistd/setxid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/unistd/setxid.c b/src/unistd/setxid.c index 487c1a16..1dfb2c01 100644 --- a/src/unistd/setxid.c +++ b/src/unistd/setxid.c @@ -30,5 +30,5 @@ int __setxid(int nr, int id, int eid, int sid) * trigger the safety kill above. */ struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .ret = 1 }; __synccall(do_setxid, &c); - return __syscall_ret(c.ret); + return __syscall_ret(c.ret > 0? -EAGAIN : c.ret); } -- 2.39.2