From: Alexander Gordeev <[email protected]>
Generic get_unmapped_area() function does sanity checks
of address and length of the area to be mapped. Yet, it
lacks checking against mmap_min_addr and mmap_end limits.
At the same time the default implementation of functions
arch_get_unmapped_area[_topdown]() and some architecture
callbacks do mmap_min_addr and mmap_end checks on its own.
Put additional checks into the generic code and do not let
architecture callbacks to get away with a possible area
outside of the allowed limits.
That could also relieve arch_get_unmapped_area[_topdown]()
callbacks of own address and length sanity checks.
Signed-off-by: Alexander Gordeev <[email protected]>
---
mm/mmap.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index d681a20eb4ea..a0fcb5ca0e06 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2168,12 +2168,13 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
unsigned long (*get_area)(struct file *, unsigned long,
unsigned long, unsigned long, unsigned long);
+ const unsigned long mmap_end = arch_get_mmap_end(addr);
unsigned long error = arch_mmap_check(addr, len, flags);
if (error)
return error;
/* Careful about overflows.. */
- if (len > TASK_SIZE)
+ if (len > mmap_end - mmap_min_addr)
return -ENOMEM;
get_area = current->mm->get_unmapped_area;
@@ -2194,7 +2195,7 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
if (IS_ERR_VALUE(addr))
return addr;
- if (addr > TASK_SIZE - len)
+ if ((addr < mmap_min_addr) || (addr > mmap_end - len))
return -ENOMEM;
if (offset_in_page(addr))
return -EINVAL;
--
2.23.0