Security: round mmap hint address above mmap_min_addr
If mmap_min_addr is set and a process attempts to mmap (not fixed) with a
non-null hint address less than mmap_min_addr the mapping will fail the
security checks. Since this is just a hint address this patch will round
such a hint address above mmap_min_addr.
gcj was found to try to be very frugal with vm usage and give hint addresses
in the 8k-32k range. Without this patch all such programs failed and with
the patch they happily get a higher address.
This patch is wrappad in CONFIG_SECURITY since mmap_min_addr doesn't exist
without it and there would be no security check possible no matter what. So
we should not bother compiling in this rounding if it is just a waste of
time.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index 938313c..f4cfc6a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -912,6 +912,9 @@
if (!len)
return -EINVAL;
+ if (!(flags & MAP_FIXED))
+ addr = round_hint_to_min(addr);
+
error = arch_mmap_check(addr, len, flags);
if (error)
return error;
diff --git a/mm/nommu.c b/mm/nommu.c
index 35622c5..b989cb9 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -829,6 +829,9 @@
void *result;
int ret;
+ if (!(flags & MAP_FIXED))
+ addr = round_hint_to_min(addr);
+
/* decide whether we should attempt the mapping, and if so what sort of
* mapping */
ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,