[SRU OEM-6.1 01/14] exec: Remove FOLL_FORCE for stack setup

Thadeu Lima de Souza Cascardo cascardo at canonical.com
Wed Jul 5 12:33:59 UTC 2023

From: Kees Cook <keescook at chromium.org>

It does not appear that FOLL_FORCE should be needed for setting up the
stack pages. They are allocated using the nascent brpm->vma, which was
newly created with VM_STACK_FLAGS, which an arch can override, but they
all appear to include VM_WRITE | VM_MAYWRITE. Remove FOLL_FORCE.

Cc: Eric Biederman <ebiederm at xmission.com>
Cc: David Hildenbrand <david at redhat.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Alexander Viro <viro at zeniv.linux.org.uk>
Cc: linux-fsdevel at vger.kernel.org
Cc: linux-mm at kvack.org
Link: https://lore.kernel.org/lkml/202211171439.CDE720EAD@keescook/
Signed-off-by: Kees Cook <keescook at chromium.org>
(cherry picked from commit cd57e443831d8eeb083c7165bce195d886e216d4)
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
 fs/exec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/exec.c b/fs/exec.c
index a0b1f0337a62..19364a5d35ee 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -199,7 +199,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 	struct page *page;
 	int ret;
-	unsigned int gup_flags = FOLL_FORCE;
+	unsigned int gup_flags = 0;
 	if (write) {

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