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Commit 6b187337 authored by Richard Weinberger's avatar Richard Weinberger
Browse files

um: Fix waitpid() usage in helper code 



If UML is executing a helper program it is using
waitpid() with the __WCLONE flag to wait for the program
as the helper is executed from a clone()'ed thread.
While using __WCLONE is perfectly fine for clone()'ed
childs it won't detect terminated childs if the helper
has issued an execve().

We have to use __WALL to wait for both clone()'ed and
regular childs to detect the termination before and
after an execve().

Reported-and-tested-by: default avatarThomas Meyer <thomas@m3y3r.de>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 37e81a01

arch/um/os-Linux/helper.c

+3 −3
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) 
			       "ret = %d\n", -n);

			ret = n;

		}

		CATCH_EINTR(waitpid(pid, NULL, __WCLONE));

		CATCH_EINTR(waitpid(pid, NULL, __WALL));

	}



out_free2:
@@ -129,7 +129,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 
		return err;

	}

	if (stack_out == NULL) {

		CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE));

		CATCH_EINTR(pid = waitpid(pid, &status, __WALL));

		if (pid < 0) {

			err = -errno;

			printk(UM_KERN_ERR "run_helper_thread - wait failed, "
@@ -148,7 +148,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 
int helper_wait(int pid)

{

	int ret, status;

	int wflags = __WCLONE;

	int wflags = __WALL;



	CATCH_EINTR(ret = waitpid(pid, &status, wflags));

	if (ret < 0) {