On 11/03/2024 10:28, Amit Daniel Kachhap wrote:
Check that the permission of the new user address does not exceed the permission of old user address for mremap syscall.
Signed-off-by: Amit Daniel Kachhap amitdaniel.kachhap@arm.com
mm/mremap.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/mm/mremap.c b/mm/mremap.c index fb648147b5d4..e3b67f55f2d8 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1091,6 +1091,9 @@ SYSCALL_DEFINE5(__retptr__(mremap), user_uintptr_t, user_ptr, unsigned long, old if (flags & MREMAP_FIXED) { if (!check_user_ptr_owning(new_user_ptr, new_addr, new_len)) goto out;
if ((cheri_perms_get(user_ptr) | cheri_perms_get(new_user_ptr))!= cheri_perms_get(user_ptr))
That won't build in !CHERI. This test is pretty specific to mremap so it probably doesn't make sense to add a generic helper. We could just add a helper in this file with the appropriate #ifdef'ing (to avoid adding #ifdef's in the main function body).
Kevin
goto out;