[PATCH AUTOSEL 5.10 15/17] lib/genalloc: fix the overflow when size is too big

Sasha Levin
2021-01-05T01:01:36Z

From: Huang Shijie <sjhuang@iluvatar.ai>

[ Upstream commit 36845663843fc59c5d794e3dc0641472e3e572da ]

Some graphic card has very big memory on chip, such as 32G bytes.

In the following case, it will cause overflow:

pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
ret = gen_pool_add(pool, 0x1000000, SZ_32G, NUMA_NO_NODE);

va = gen_pool_alloc(pool, SZ_4G);

The overflow occurs in gen_pool_alloc_algo_owner():

....
size = nbits << order;
....

The @nbits is "int" type, so it will overflow.
Then the gen_pool_avail() will return the wrong value.

This patch converts some "int" to "unsigned long", and
changes the compare code in while.

Link: https://lkml.kernel.org/r/20201229060657.3389-1-sjhuang@iluvatar.ai
Signed-off-by: Huang Shijie <sjhuang@iluvatar.ai>
Reported-by: Shi Jiasheng <jiasheng.shi@iluvatar.ai>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/genalloc.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/lib/genalloc.c b/lib/genalloc.c
index 7f1244b5294a8..dab97bb69df63 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -81,14 +81,14 @@ static int clear_bits_ll(unsigned long *addr, unsigned long mask_to_clear)
* users set the same bit, one user will return remain bits, otherwise
* return 0.
*/
-static int bitmap_set_ll(unsigned long *map, int start, int nr)
+static int bitmap_set_ll(unsigned long *map, unsigned long start, unsigned long nr)
{
unsigned long *p = map + BIT_WORD(start);
- const int size = start + nr;
+ const unsigned long size = start + nr;
int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

- while (nr - bits_to_set >= 0) {
+ while (nr >= bits_to_set) {
if (set_bits_ll(p, mask_to_set))
return nr;
nr -= bits_to_set;
@@ -116,14 +116,15 @@ static int bitmap_set_ll(unsigned long *map, int start, int nr)
* users clear the same bit, one user will return remain bits,
* otherwise return 0.
*/
-static int bitmap_clear_ll(unsigned long *map, int start, int nr)
+static unsigned long
+bitmap_clear_ll(unsigned long *map, unsigned long start, unsigned long nr)
{
unsigned long *p = map + BIT_WORD(start);
- const int size = start + nr;
+ const unsigned long size = start + nr;
int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

- while (nr - bits_to_clear >= 0) {
+ while (nr >= bits_to_clear) {
if (clear_bits_ll(p, mask_to_clear))
return nr;
nr -= bits_to_clear;
@@ -183,8 +184,8 @@ int gen_pool_add_owner(struct gen_pool *pool, unsigned long virt, phys_addr_t ph
size_t size, int nid, void *owner)
{
struct gen_pool_chunk *chunk;
- int nbits = size >> pool->min_alloc_order;
- int nbytes = sizeof(struct gen_pool_chunk) +
+ unsigned long nbits = size >> pool->min_alloc_order;
+ unsigned long nbytes = sizeof(struct gen_pool_chunk) +
BITS_TO_LONGS(nbits) * sizeof(long);

chunk = vzalloc_node(nbytes, nid);
@@ -242,7 +243,7 @@ void gen_pool_destroy(struct gen_pool *pool)
struct list_head *_chunk, *_next_chunk;
struct gen_pool_chunk *chunk;
int order = pool->min_alloc_order;
- int bit, end_bit;
+ unsigned long bit, end_bit;

list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
@@ -278,7 +279,7 @@ unsigned long gen_pool_alloc_algo_owner(struct gen_pool *pool, size_t size,
struct gen_pool_chunk *chunk;
unsigned long addr = 0;
int order = pool->min_alloc_order;
- int nbits, start_bit, end_bit, remain;
+ unsigned long nbits, start_bit, end_bit, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
BUG_ON(in_nmi());
@@ -487,7 +488,7 @@ void gen_pool_free_owner(struct gen_pool *pool, unsigned long addr, size_t size,
{
struct gen_pool_chunk *chunk;
int order = pool->min_alloc_order;
- int start_bit, nbits, remain;
+ unsigned long start_bit, nbits, remain;

#ifndef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
BUG_ON(in_nmi());
@@ -755,7 +756,7 @@ unsigned long gen_pool_best_fit(unsigned long *map, unsigned long size,
index = bitmap_find_next_zero_area(map, size, start, nr, 0);

while (index < size) {
- int next_bit = find_next_bit(map, size, index + nr);
+ unsigned long next_bit = find_next_bit(map, size, index + nr);
if ((next_bit - index) < len) {
len = next_bit - index;
start_bit = index;
--
2.27.0