The patch titled
Subject: memfd: check for non-NULL file_seals in memfd_create() syscall
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
memfd-check-for-non-null-file_seals-in-memfd_create-syscall.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memfd-check-for-non-null-file_seals-in-memfd_create-syscall.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Subject: memfd: check for non-NULL file_seals in memfd_create() syscall
Date: Wed, 7 Jun 2023 15:24:27 +0200
Ensure that file_seals is non-NULL before using it in the memfd_create()
syscall. One situation in which memfd_file_seals_ptr() could return a
NULL pointer is when CONFIG_SHMEM=n.
Link: https://lkml.kernel.org/r/20230607132427.2867435-1-roberto.sassu@xxxxxxxxxxxxxxx
Fixes: 47b9012ecdc7 ("shmem: add sealing support to hugetlb-backed memfd")
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Cc: Marc-Andr Lureau <marcandre.lureau@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memfd.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
--- a/mm/memfd.c~memfd-check-for-non-null-file_seals-in-memfd_create-syscall
+++ a/mm/memfd.c
@@ -371,12 +371,15 @@ SYSCALL_DEFINE2(memfd_create,
inode->i_mode &= ~0111;
file_seals = memfd_file_seals_ptr(file);
- *file_seals &= ~F_SEAL_SEAL;
- *file_seals |= F_SEAL_EXEC;
+ if (file_seals) {
+ *file_seals &= ~F_SEAL_SEAL;
+ *file_seals |= F_SEAL_EXEC;
+ }
} else if (flags & MFD_ALLOW_SEALING) {
/* MFD_EXEC and MFD_ALLOW_SEALING are set */
file_seals = memfd_file_seals_ptr(file);
- *file_seals &= ~F_SEAL_SEAL;
+ if (file_seals)
+ *file_seals &= ~F_SEAL_SEAL;
}
fd_install(fd, file);
_
Patches currently in -mm which might be from roberto.sassu@xxxxxxxxxx are
memfd-check-for-non-null-file_seals-in-memfd_create-syscall.patch
