From: Roberto Sassu <roberto.sassu@xxxxxxxxxx> [ Upstream commit 935d44acf621aa0688fef8312dec3e5940f38f4e ] 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 when CONFIG_SHMEM=n, oopsing the kernel. 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> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- mm/memfd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memfd.c b/mm/memfd.c index fae4142f7d254..278e5636623e6 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -330,7 +330,8 @@ SYSCALL_DEFINE2(memfd_create, if (flags & MFD_ALLOW_SEALING) { file_seals = memfd_file_seals_ptr(file); - *file_seals &= ~F_SEAL_SEAL; + if (file_seals) + *file_seals &= ~F_SEAL_SEAL; } fd_install(fd, file); -- 2.39.2
