Add a check that the requested protection bits does not exceed the maximum protection bits.
Signed-off-by: Amit Daniel Kachhap amitdaniel.kachhap@arm.com --- mm/mmap.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/mm/mmap.c b/mm/mmap.c index 6b66e94f0dfb..a1f85c22321a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1477,11 +1477,17 @@ user_uintptr_t ksys_mmap_pgoff(user_uintptr_t usrptr, unsigned long len, * Introduce checks for PCuABI: * - MAP_GROWSDOWN flag do not have fixed bounds and hence not * supported in PCuABI reservation model. + * - PCuABI reservation model introduces the concept of maximum + * protection the mappings can have. Add a check to make sure the + * requested protection does not exceed the maximum protection. */ if (flags & MAP_GROWSDOWN) { retval = -EOPNOTSUPP; goto out_fput; } + if ((PROT_MAX_EXTRACT(prot) != 0) && + ((PROT_EXTRACT(prot) & PROT_MAX_EXTRACT(prot)) != PROT_EXTRACT(prot))) + goto out_fput; if (cheri_tag_get(usrptr)) { if (!(flags & MAP_FIXED) || !capability_owns_range(usrptr, addr, len)) goto out_fput;