| Message ID | 20220904074647.GA64291@cloud-MacBookPro (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: fix dereferencing possible ERR_PTR | expand |
On 9/4/22 2:46 PM, Binyi Han wrote: > Smatch checker complains that 'secretmem_mnt' dereferencing possible > ERR_PTR(). > Let the function return if 'secretmem_mnt' is ERR_PTR, to avoid > deferencing it. > > Signed-off-by: Binyi Han <dantengknight@gmail.com> > --- Fixes: 1507f51255c9ff07d75909a84e7c0d7f3c4b2f49 ("mm: introduce memfd_secret system call to create "secret" memory areas") > mm/secretmem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/secretmem.c b/mm/secretmem.c > index e3e9590c6fb3..3f7154099795 100644 > --- a/mm/secretmem.c > +++ b/mm/secretmem.c > @@ -285,7 +285,7 @@ static int secretmem_init(void) > > secretmem_mnt = kern_mount(&secretmem_fs); > if (IS_ERR(secretmem_mnt)) > - ret = PTR_ERR(secretmem_mnt); > + return PTR_ERR(secretmem_mnt); > > /* prevent secretmem mappings from ever getting PROT_EXEC */ > secretmem_mnt->mnt_flags |= MNT_NOEXEC; I agree that doing: secretmem_mnt->mnt_flags |= MNT_NOEXEC; when IS_ERR(secretmem_mnt) evaluates to true is wrong. But I have a question: what happen if you invoke memfd_secret() syscall when @secretmem_mnt is an ERR_PTR? Shouldn't we also guard the memfd_secret() path? diff --git a/mm/secretmem.c b/mm/secretmem.c index e3e9590c6fb3..2d52508d47a9 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -230,18 +230,21 @@ static struct file *secretmem_file_create(unsigned long flags) SYSCALL_DEFINE1(memfd_secret, unsigned int, flags) { struct file *file; int fd, err; /* make sure local flags do not confict with global fcntl.h */ BUILD_BUG_ON(SECRETMEM_FLAGS_MASK & O_CLOEXEC); + if (IS_ERR(secretmem_mnt)) + return PTR_ERR(secretmem_mnt); + if (!secretmem_enable) return -ENOSYS; if (flags & ~(SECRETMEM_FLAGS_MASK | O_CLOEXEC)) return -EINVAL; if (atomic_read(&secretmem_users) < 0) return -ENFILE; fd = get_unused_fd_flags(flags & O_CLOEXEC);
diff --git a/mm/secretmem.c b/mm/secretmem.c index e3e9590c6fb3..3f7154099795 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -285,7 +285,7 @@ static int secretmem_init(void) secretmem_mnt = kern_mount(&secretmem_fs); if (IS_ERR(secretmem_mnt)) - ret = PTR_ERR(secretmem_mnt); + return PTR_ERR(secretmem_mnt); /* prevent secretmem mappings from ever getting PROT_EXEC */ secretmem_mnt->mnt_flags |= MNT_NOEXEC;
Smatch checker complains that 'secretmem_mnt' dereferencing possible ERR_PTR(). Let the function return if 'secretmem_mnt' is ERR_PTR, to avoid deferencing it. Signed-off-by: Binyi Han <dantengknight@gmail.com> --- mm/secretmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)