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 both compiling in this rounding if it is just a
waste of time.
Signed-off-by: Eric Paris <[email protected]>
---
mm/mmap.c | 10 ++++++++++
mm/nommu.c | 10 ++++++++++
2 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index 938313c..0c3ff74 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -912,6 +912,16 @@ unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
if (!len)
return -EINVAL;
+#ifdef CONFIG_SECURITY
+ /*
+ * If a hint addr is less than mmap_min_addr change addr to be as
+ * low as possible but still greater than mmap_min_addr
+ */
+ if (!(flags & MAP_FIXED) && ((void *)addr != NULL) &&
+ (addr < mmap_min_addr))
+ addr = PAGE_ALIGN(mmap_min_addr);
+#endif
+
error = arch_mmap_check(addr, len, flags);
if (error)
return error;
diff --git a/mm/nommu.c b/mm/nommu.c
index 35622c5..ea4d20a 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -829,6 +829,16 @@ unsigned long do_mmap_pgoff(struct file *file,
void *result;
int ret;
+#ifdef CONFIG_SECURITY
+ /*
+ * If a hint addr is less than mmap_min_addr change addr to be as
+ * low as possible, but still greater than mmap_min_addr
+ */
+ if (!(flags & MAP_FIXED) && ((void *)addr != NULL) &&
+ (addr < mmap_min_addr))
+ addr = PAGE_ALIGN(mmap_min_addr);
+#endif
+
/* decide whether we should attempt the mapping, and if so what sort of
* mapping */
ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
-
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