[PATCH AUTOSEL 6.10 14/27] udf: prevent integer overflow in udf_bitmap_free_blocks()

Sasha Levin
2024-07-28T00:54:10Z

From: Roman Smirnov <r.smirnov@omp.ru>

[ Upstream commit 56e69e59751d20993f243fb7dd6991c4e522424c ]

An overflow may occur if the function is called with the last
block and an offset greater than zero. It is necessary to add
a check to avoid this.

Found by Linux Verification Center (linuxtesting.org) with Svace.

[JK: Make test cover also unalloc table freeing]

Link: https://patch.msgid.link/20240620072413.7448-1-r.smirnov@omp.ru
Suggested-by: Jan Kara <jack@suse.com>
Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/udf/balloc.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/fs/udf/balloc.c b/fs/udf/balloc.c
index ab3ffc355949d..2192c4a1ba98b 100644
--- a/fs/udf/balloc.c
+++ b/fs/udf/balloc.c
@@ -18,6 +18,7 @@
#include "udfdecl.h"

#include <linux/bitops.h>
+#include <linux/overflow.h>

#include "udf_i.h"
#include "udf_sb.h"
@@ -129,7 +130,6 @@ static void udf_bitmap_free_blocks(struct super_block *sb,
{
struct udf_sb_info *sbi = UDF_SB(sb);
struct buffer_head *bh = NULL;
- struct udf_part_map *partmap;
unsigned long block;
unsigned long block_group;
unsigned long bit;
@@ -138,19 +138,9 @@ static void udf_bitmap_free_blocks(struct super_block *sb,
unsigned long overflow;

mutex_lock(&sbi->s_alloc_mutex);
- partmap = &sbi->s_partmaps[bloc->partitionReferenceNum];
- if (bloc->logicalBlockNum + count < count ||
- (bloc->logicalBlockNum + count) > partmap->s_partition_len) {
- udf_debug("%u < %d || %u + %u > %u\n",
- bloc->logicalBlockNum, 0,
- bloc->logicalBlockNum, count,
- partmap->s_partition_len);
- goto error_return;
- }
-
+ /* We make sure this cannot overflow when mounting the filesystem */
block = bloc->logicalBlockNum + offset +
(sizeof(struct spaceBitmapDesc) << 3);
-
do {
overflow = 0;
block_group = block >> (sb->s_blocksize_bits + 3);
@@ -380,7 +370,6 @@ static void udf_table_free_blocks(struct super_block *sb,
uint32_t count)
{
struct udf_sb_info *sbi = UDF_SB(sb);
- struct udf_part_map *partmap;
uint32_t start, end;
uint32_t elen;
struct kernel_lb_addr eloc;
@@ -389,16 +378,6 @@ static void udf_table_free_blocks(struct super_block *sb,
struct udf_inode_info *iinfo;

mutex_lock(&sbi->s_alloc_mutex);
- partmap = &sbi->s_partmaps[bloc->partitionReferenceNum];
- if (bloc->logicalBlockNum + count < count ||
- (bloc->logicalBlockNum + count) > partmap->s_partition_len) {
- udf_debug("%u < %d || %u + %u > %u\n",
- bloc->logicalBlockNum, 0,
- bloc->logicalBlockNum, count,
- partmap->s_partition_len);
- goto error_return;
- }
-
iinfo = UDF_I(table);
udf_add_free_space(sb, sbi->s_partition, count);

@@ -673,6 +652,17 @@ void udf_free_blocks(struct super_block *sb, struct inode *inode,
{
uint16_t partition = bloc->partitionReferenceNum;
struct udf_part_map *map = &UDF_SB(sb)->s_partmaps[partition];
+ uint32_t blk;
+
+ if (check_add_overflow(bloc->logicalBlockNum, offset, &blk) ||
+ check_add_overflow(blk, count, &blk) ||
+ bloc->logicalBlockNum + count > map->s_partition_len) {
+ udf_debug("Invalid request to free blocks: (%d, %u), off %u, "
+ "len %u, partition len %u\n",
+ partition, bloc->logicalBlockNum, offset, count,
+ map->s_partition_len);
+ return;
+ }

if (map->s_partition_flags & UDF_PART_FLAG_UNALLOC_BITMAP) {
udf_bitmap_free_blocks(sb, map->s_uspace.s_bitmap,
--
2.43.0