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ashmem: ensure ashmem fds are CLOEXEC.

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Fix the memfd_create(2) path and add the missing unit test.

Bug: https://issuetracker.google.com/165667331
Test: treehugger
Change-Id: Ibb5c1d0f9d7caba1df04d1f03e82e55026d9f86a
This commit is contained in:
Elliott Hughes 2020-09-03 10:53:16 -07:00
parent 6233b23918
commit 790ef05793
2 changed files with 12 additions and 3 deletions
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10
libcutils/ashmem-dev.cpp
View file

@ -159,9 +159,11 @@ static bool __has_memfd_support() {
return false;
}
/* Check if kernel support exists, otherwise fall back to ashmem */
// Check if kernel support exists, otherwise fall back to ashmem.
// This code needs to build on old API levels, so we can't use the libc
// wrapper.
android::base::unique_fd fd(
syscall(__NR_memfd_create, "test_android_memfd", MFD_ALLOW_SEALING));
syscall(__NR_memfd_create, "test_android_memfd", MFD_CLOEXEC | MFD_ALLOW_SEALING));
if (fd == -1) {
ALOGE("memfd_create failed: %s, no memfd support.\n", strerror(errno));
return false;
@ -333,7 +335,9 @@ int ashmem_valid(int fd)
}
static int memfd_create_region(const char* name, size_t size) {
android::base::unique_fd fd(syscall(__NR_memfd_create, name, MFD_ALLOW_SEALING));
// This code needs to build on old API levels, so we can't use the libc
// wrapper.
android::base::unique_fd fd(syscall(__NR_memfd_create, name, MFD_CLOEXEC | MFD_ALLOW_SEALING));
if (fd == -1) {
ALOGE("memfd_create(%s, %zd) failed: %s\n", name, size, strerror(errno));

5
libcutils/ashmem_test.cpp
View file

@ -35,6 +35,11 @@ void TestCreateRegion(size_t size, unique_fd &fd, int prot) {
ASSERT_TRUE(ashmem_valid(fd));
ASSERT_EQ(size, static_cast<size_t>(ashmem_get_size_region(fd)));
ASSERT_EQ(0, ashmem_set_prot_region(fd, prot));
// We've been inconsistent historically about whether or not these file
// descriptors were CLOEXEC. Make sure we're consistent going forward.
// https://issuetracker.google.com/165667331
ASSERT_EQ(FD_CLOEXEC, (fcntl(fd, F_GETFD) & FD_CLOEXEC));
}
void TestMmap(const unique_fd& fd, size_t size, int prot, void** region, off_t off = 0) {