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Subject[PATCH] mm: kmemleak: Avoid using __va() on addresses that don't have a lowmem mapping
Date
Some of the kmemleak_*() callbacks in memblock, bootmem, CMA convert a
physical address to a virtual one using __va(). However, such physical
addresses may sometimes be located in highmem and using __va() is
incorrect, leading to inconsistent object tracking in kmemleak.

The following functions have been added to the kmemleak API and they
take a physical address as the object pointer. They only perform the
corresponding action if the address has a lowmem mapping:

kmemleak_alloc_phys
kmemleak_free_part_phys
kmemleak_not_leak_phys
kmemleak_ignore_phys

The affected calling places have been updated to use the new kmemleak API.

Reported-by: Vignesh R <vigneshr@ti.com>
Tested-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

Not entirely sure about cc'ing stable though. This bug has been around
since the beginnings of kmemleak and I only now got a bug report. It's
either because the preconditions are hard to meet or/and people don't
enable kmemleak very often. Once this patch hits mainline, I can send it
separately to linux-stable for versions we can reproduce the issue on
(4.4 seems to be one of them).

Documentation/kmemleak.txt | 9 +++++++++
include/linux/kmemleak.h | 26 ++++++++++++++++++++++++++
mm/bootmem.c | 6 +++---
mm/cma.c | 2 +-
mm/memblock.c | 8 ++++----
mm/nobootmem.c | 2 +-
6 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/Documentation/kmemleak.txt b/Documentation/kmemleak.txt
index 18e24abb3ecf..35e1a8891e3a 100644
--- a/Documentation/kmemleak.txt
+++ b/Documentation/kmemleak.txt
@@ -155,6 +155,15 @@ kmemleak_erase - erase an old value in a pointer variable
kmemleak_alloc_recursive - as kmemleak_alloc but checks the recursiveness
kmemleak_free_recursive - as kmemleak_free but checks the recursiveness

+The following functions take a physical address as the object pointer
+and only perform the corresponding action if the address has a lowmem
+mapping:
+
+kmemleak_alloc_phys
+kmemleak_free_part_phys
+kmemleak_not_leak_phys
+kmemleak_ignore_phys
+
Dealing with false positives/negatives
--------------------------------------

diff --git a/include/linux/kmemleak.h b/include/linux/kmemleak.h
index 4894c6888bc6..380f72bc3657 100644
--- a/include/linux/kmemleak.h
+++ b/include/linux/kmemleak.h
@@ -21,6 +21,7 @@
#ifndef __KMEMLEAK_H
#define __KMEMLEAK_H

+#include <linux/mm.h>
#include <linux/slab.h>

#ifdef CONFIG_DEBUG_KMEMLEAK
@@ -109,4 +110,29 @@ static inline void kmemleak_no_scan(const void *ptr)

#endif /* CONFIG_DEBUG_KMEMLEAK */

+static inline void kmemleak_alloc_phys(phys_addr_t phys, size_t size,
+ int min_count, gfp_t gfp)
+{
+ if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
+ kmemleak_alloc(__va(phys), size, min_count, gfp);
+}
+
+static inline void kmemleak_free_part_phys(phys_addr_t phys, size_t size)
+{
+ if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
+ kmemleak_free_part(__va(phys), size);
+}
+
+static inline void kmemleak_not_leak_phys(phys_addr_t phys)
+{
+ if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
+ kmemleak_not_leak(__va(phys));
+}
+
+static inline void kmemleak_ignore_phys(phys_addr_t phys)
+{
+ if (!IS_ENABLED(CONFIG_HIGHMEM) || phys < __pa(high_memory))
+ kmemleak_ignore(__va(phys));
+}
+
#endif /* __KMEMLEAK_H */
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 0aa7dda52402..80f1d70bad2d 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -158,7 +158,7 @@ void __init free_bootmem_late(unsigned long physaddr, unsigned long size)
{
unsigned long cursor, end;

- kmemleak_free_part(__va(physaddr), size);
+ kmemleak_free_part_phys(physaddr, size);

cursor = PFN_UP(physaddr);
end = PFN_DOWN(physaddr + size);
@@ -402,7 +402,7 @@ void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
{
unsigned long start, end;

- kmemleak_free_part(__va(physaddr), size);
+ kmemleak_free_part_phys(physaddr, size);

start = PFN_UP(physaddr);
end = PFN_DOWN(physaddr + size);
@@ -423,7 +423,7 @@ void __init free_bootmem(unsigned long physaddr, unsigned long size)
{
unsigned long start, end;

- kmemleak_free_part(__va(physaddr), size);
+ kmemleak_free_part_phys(physaddr, size);

start = PFN_UP(physaddr);
end = PFN_DOWN(physaddr + size);
diff --git a/mm/cma.c b/mm/cma.c
index bd0e1412475e..384c2cb51b56 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -336,7 +336,7 @@ int __init cma_declare_contiguous(phys_addr_t base,
* kmemleak scans/reads tracked objects for pointers to other
* objects but this address isn't mapped and accessible
*/
- kmemleak_ignore(phys_to_virt(addr));
+ kmemleak_ignore_phys(addr);
base = addr;
}

diff --git a/mm/memblock.c b/mm/memblock.c
index 483197ef613f..30ecea7b45d1 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -723,7 +723,7 @@ int __init_memblock memblock_free(phys_addr_t base, phys_addr_t size)
(unsigned long long)base + size - 1,
(void *)_RET_IP_);

- kmemleak_free_part(__va(base), size);
+ kmemleak_free_part_phys(base, size);
return memblock_remove_range(&memblock.reserved, base, size);
}

@@ -1152,7 +1152,7 @@ static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
* The min_count is set to 0 so that memblock allocations are
* never reported as leaks.
*/
- kmemleak_alloc(__va(found), size, 0, 0);
+ kmemleak_alloc_phys(found, size, 0, 0);
return found;
}
return 0;
@@ -1399,7 +1399,7 @@ void __init __memblock_free_early(phys_addr_t base, phys_addr_t size)
memblock_dbg("%s: [%#016llx-%#016llx] %pF\n",
__func__, (u64)base, (u64)base + size - 1,
(void *)_RET_IP_);
- kmemleak_free_part(__va(base), size);
+ kmemleak_free_part_phys(base, size);
memblock_remove_range(&memblock.reserved, base, size);
}

@@ -1419,7 +1419,7 @@ void __init __memblock_free_late(phys_addr_t base, phys_addr_t size)
memblock_dbg("%s: [%#016llx-%#016llx] %pF\n",
__func__, (u64)base, (u64)base + size - 1,
(void *)_RET_IP_);
- kmemleak_free_part(__va(base), size);
+ kmemleak_free_part_phys(base, size);
cursor = PFN_UP(base);
end = PFN_DOWN(base + size);

diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index bd05a70f44b9..a056d31dff7e 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -81,7 +81,7 @@ void __init free_bootmem_late(unsigned long addr, unsigned long size)
{
unsigned long cursor, end;

- kmemleak_free_part(__va(addr), size);
+ kmemleak_free_part_phys(addr, size);

cursor = PFN_UP(addr);
end = PFN_DOWN(addr + size);
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