The patch titled
Subject: mm/mmap.c: add more sanity checks to get_unmapped_area()
has been added to the -mm tree. Its filename is
mm-mmapc-add-more-sanity-checks-to-get_unmapped_area.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-mmapc-add-more-sanity-checks-to-get_unmapped_area.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-mmapc-add-more-sanity-checks-to-get_unmapped_area.patch
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------------------------------------------------------
From: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Subject: mm/mmap.c: add more sanity checks to get_unmapped_area()
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 their 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.
Link: http://lkml.kernel.org/r/d14f2cff3c891ef2c4b0337d737c6f04beacb124.1584958099.git.agordeev@xxxxxxxxxxxxx
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/mm/mmap.c~mm-mmapc-add-more-sanity-checks-to-get_unmapped_area
+++ a/mm/mmap.c
@@ -2208,12 +2208,13 @@ get_unmapped_area(struct file *file, uns
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;
@@ -2234,7 +2235,7 @@ get_unmapped_area(struct file *file, uns
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;
_
Patches currently in -mm which might be from agordeev@xxxxxxxxxxxxx are
mm-mmapc-add-more-sanity-checks-to-get_unmapped_area.patch
mm-mmapc-do-not-allow-mappings-outside-of-allowed-limits.patch
