Fix SETOWN_EX return value.

Return on success should be 0, not size of the struct copied out.

PiperOrigin-RevId: 324029193

3 files changed, 28 insertions, 22 deletions

diff --git a/pkg/sentry/syscalls/linux/sys_file.go b/pkg/sentry/syscalls/linux/sys_file.go
index 2797c6a72..8cf6401e7 100644
--- a/pkg/sentry/syscalls/linux/sys_file.go
+++ b/pkg/sentry/syscalls/linux/sys_file.go
@@ -1057,7 +1057,7 @@ func Fcntl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 	case linux.F_SETOWN_EX:
 		addr := args[2].Pointer()
 		var owner linux.FOwnerEx
-		n, err := t.CopyIn(addr, &owner)
+		_, err := t.CopyIn(addr, &owner)
 		if err != nil {
 			return 0, nil, err
 		}
@@ -1069,21 +1069,21 @@ func Fcntl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 				return 0, nil, syserror.ESRCH
 			}
 			a.SetOwnerTask(t, task)
-			return uintptr(n), nil, nil
+			return 0, nil, nil
 		case linux.F_OWNER_PID:
 			tg := t.PIDNamespace().ThreadGroupWithID(kernel.ThreadID(owner.PID))
 			if tg == nil {
 				return 0, nil, syserror.ESRCH
 			}
 			a.SetOwnerThreadGroup(t, tg)
-			return uintptr(n), nil, nil
+			return 0, nil, nil
 		case linux.F_OWNER_PGRP:
 			pg := t.PIDNamespace().ProcessGroupWithID(kernel.ProcessGroupID(owner.PID))
 			if pg == nil {
 				return 0, nil, syserror.ESRCH
 			}
 			a.SetOwnerProcessGroup(t, pg)
-			return uintptr(n), nil, nil
+			return 0, nil, nil
 		default:
 			return 0, nil, syserror.EINVAL
 		}
diff --git a/pkg/sentry/syscalls/linux/vfs2/fd.go b/pkg/sentry/syscalls/linux/vfs2/fd.go
index 517394ba9..67f191551 100644
--- a/pkg/sentry/syscalls/linux/vfs2/fd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/fd.go
@@ -185,11 +185,11 @@ func Fcntl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 		return 0, nil, err
 	case linux.F_SETOWN_EX:
 		var owner linux.FOwnerEx
-		n, err := t.CopyIn(args[2].Pointer(), &owner)
+		_, err := t.CopyIn(args[2].Pointer(), &owner)
 		if err != nil {
 			return 0, nil, err
 		}
-		return uintptr(n), nil, setAsyncOwner(t, file, owner.Type, owner.PID)
+		return 0, nil, setAsyncOwner(t, file, owner.Type, owner.PID)
 	case linux.F_GETPIPE_SZ:
 		pipefile, ok := file.Impl().(*pipe.VFSPipeFD)
 		if !ok {
diff --git a/test/syscalls/linux/fcntl.cc b/test/syscalls/linux/fcntl.cc
index 5467fa2c8..34016d4bd 100644
--- a/test/syscalls/linux/fcntl.cc
+++ b/test/syscalls/linux/fcntl.cc
@@ -1004,7 +1004,8 @@ TEST(FcntlTest, SetOwnPid) {
   pid_t pid;
   EXPECT_THAT(pid = getpid(), SyscallSucceeds());
 
-  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, pid), SyscallSucceeds());
+  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, pid),
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(pid));
@@ -1018,7 +1019,8 @@ TEST(FcntlTest, SetOwnPgrp) {
   pid_t pgid;
   EXPECT_THAT(pgid = getpgrp(), SyscallSucceeds());
 
-  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, -pgid), SyscallSucceeds());
+  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, -pgid),
+              SyscallSucceedsWithValue(0));
 
   // Verify with F_GETOWN_EX; using F_GETOWN on Linux may incorrectly treat the
   // negative return value as an error, converting the return value to -1 and
@@ -1038,8 +1040,10 @@ TEST(FcntlTest, SetOwnUnset) {
   // Set and unset pid.
   pid_t pid;
   EXPECT_THAT(pid = getpid(), SyscallSucceeds());
-  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, pid), SyscallSucceeds());
-  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, 0), SyscallSucceeds());
+  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, pid),
+              SyscallSucceedsWithValue(0));
+  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, 0),
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(0));
@@ -1047,8 +1051,10 @@ TEST(FcntlTest, SetOwnUnset) {
   // Set and unset pgid.
   pid_t pgid;
   EXPECT_THAT(pgid = getpgrp(), SyscallSucceeds());
-  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, -pgid), SyscallSucceeds());
-  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, 0), SyscallSucceeds());
+  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, -pgid),
+              SyscallSucceedsWithValue(0));
+  ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN, 0),
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(0));
@@ -1120,7 +1126,7 @@ TEST(FcntlTest, SetOwnExTid) {
   EXPECT_THAT(owner.pid = syscall(__NR_gettid), SyscallSucceeds());
 
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(owner.pid));
@@ -1136,7 +1142,7 @@ TEST(FcntlTest, SetOwnExPid) {
   EXPECT_THAT(owner.pid = getpid(), SyscallSucceeds());
 
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(owner.pid));
@@ -1152,7 +1158,7 @@ TEST(FcntlTest, SetOwnExPgrp) {
   EXPECT_THAT(set_owner.pid = getpgrp(), SyscallSucceeds());
 
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &set_owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   // Verify with F_GETOWN_EX; using F_GETOWN on Linux may incorrectly treat the
   // negative return value as an error, converting the return value to -1 and
@@ -1176,10 +1182,10 @@ TEST(FcntlTest, SetOwnExUnset) {
   owner.type = F_OWNER_PID;
   EXPECT_THAT(owner.pid = getpid(), SyscallSucceeds());
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
   owner.pid = 0;
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(0));
@@ -1188,10 +1194,10 @@ TEST(FcntlTest, SetOwnExUnset) {
   owner.type = F_OWNER_PGRP;
   EXPECT_THAT(owner.pid = getpgrp(), SyscallSucceeds());
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
   owner.pid = 0;
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   EXPECT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN),
               SyscallSucceedsWithValue(0));
@@ -1207,7 +1213,7 @@ TEST(FcntlTest, GetOwnExTid) {
   EXPECT_THAT(set_owner.pid = syscall(__NR_gettid), SyscallSucceeds());
 
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &set_owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   f_owner_ex got_owner = {};
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN_EX, &got_owner),
@@ -1225,7 +1231,7 @@ TEST(FcntlTest, GetOwnExPid) {
   EXPECT_THAT(set_owner.pid = getpid(), SyscallSucceeds());
 
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &set_owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   f_owner_ex got_owner = {};
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN_EX, &got_owner),
@@ -1243,7 +1249,7 @@ TEST(FcntlTest, GetOwnExPgrp) {
   EXPECT_THAT(set_owner.pid = getpgrp(), SyscallSucceeds());
 
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_SETOWN_EX, &set_owner),
-              SyscallSucceeds());
+              SyscallSucceedsWithValue(0));
 
   f_owner_ex got_owner = {};
   ASSERT_THAT(syscall(__NR_fcntl, s.get(), F_GETOWN_EX, &got_owner),