* [PATCH] mm: fix dereferencing possible ERR_PTR
@ 2022-09-04 7:46 Binyi Han
2022-09-04 8:39 ` Ammar Faizi
0 siblings, 1 reply; 2+ messages in thread
From: Binyi Han @ 2022-09-04 7:46 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-mm, linux-kernel, kernel-janitors
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(-)
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;
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] mm: fix dereferencing possible ERR_PTR
2022-09-04 7:46 [PATCH] mm: fix dereferencing possible ERR_PTR Binyi Han
@ 2022-09-04 8:39 ` Ammar Faizi
0 siblings, 0 replies; 2+ messages in thread
From: Ammar Faizi @ 2022-09-04 8:39 UTC (permalink / raw)
To: Binyi Han, Andrew Morton
Cc: Mike Rapoport, Linux Memory Management Mailing List,
Linux Kernel Mailing List, kernel-janitors, Hagen Paul Pfeifer,
James Bottomley
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);
--
Ammar Faizi
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-09-04 8:39 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-04 7:46 [PATCH] mm: fix dereferencing possible ERR_PTR Binyi Han
2022-09-04 8:39 ` Ammar Faizi
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).