fix set hostname

Previously, when we set hostname:

$ strace hostname abc
...
sethostname("abc", 3) = -1 ENAMETOOLONG (File name too long)
...

According to man 2 sethostname:

"The len argument specifies the number of bytes in name. (Thus, name
does not require a terminating null byte.)"

We wrongly use the CopyStringIn() to check terminating zero byte in
the implementation of sethostname syscall.

To fix this, we use CopyInBytes() instead.

Fixes: #861

Reported-by: chenglang.hy <chenglang.hy@antfin.com>
Signed-off-by: Jianfeng Tan <henry.tjf@antfin.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/test/syscalls/linux/uname.cc b/test/syscalls/linux/uname.cc
index 0a5d91017..d8824b171 100644
--- a/test/syscalls/linux/uname.cc
+++ b/test/syscalls/linux/uname.cc
@@ -41,6 +41,19 @@ TEST(UnameTest, Sanity) {
 TEST(UnameTest, SetNames) {
   SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
 
+  char hostname[65];
+  ASSERT_THAT(sethostname("0123456789", 3), SyscallSucceeds());
+  EXPECT_THAT(gethostname(hostname, sizeof(hostname)), SyscallSucceeds());
+  EXPECT_EQ(absl::string_view(hostname), "012");
+
+  ASSERT_THAT(sethostname("0123456789\0xxx", 11), SyscallSucceeds());
+  EXPECT_THAT(gethostname(hostname, sizeof(hostname)), SyscallSucceeds());
+  EXPECT_EQ(absl::string_view(hostname), "0123456789");
+
+  ASSERT_THAT(sethostname("0123456789\0xxx", 12), SyscallSucceeds());
+  EXPECT_THAT(gethostname(hostname, sizeof(hostname)), SyscallSucceeds());
+  EXPECT_EQ(absl::string_view(hostname), "0123456789");
+
   constexpr char kHostname[] = "wubbalubba";
   ASSERT_THAT(sethostname(kHostname, sizeof(kHostname)), SyscallSucceeds());
 
@@ -54,7 +67,6 @@ TEST(UnameTest, SetNames) {
   EXPECT_EQ(absl::string_view(buf.domainname), kDomainname);
 
   // These should just be glibc wrappers that also call uname(2).
-  char hostname[65];
   EXPECT_THAT(gethostname(hostname, sizeof(hostname)), SyscallSucceeds());
   EXPECT_EQ(absl::string_view(hostname), kHostname);