ext2: Use kvmalloc() for group descriptor array

[ Upstream commit e7c7fbb9a8574ebd89cc05db49d806c7476863ad ]

Array of group descriptor block buffers can get rather large. In theory
in can reach 1MB for perfectly valid filesystem and even more for
maliciously crafted ones. Use kvmalloc() to allocate the array to avoid
straining memory allocator with large order allocations unnecessarily.

Reported-by: syzbot+0f2f7e65a3007d39539f@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index b3232845d0c447a093fb45b891006d613c544684..f53ab39bb8e87169f11cbe5593e740a09bd0eb93 100644 (file)
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -163,7 +163,7 @@ static void ext2_put_super (struct super_block * sb)
        db_count = sbi->s_gdb_count;
        for (i = 0; i < db_count; i++)
                brelse(sbi->s_group_desc[i]);
-       kfree(sbi->s_group_desc);
+       kvfree(sbi->s_group_desc);
        kfree(sbi->s_debts);
        percpu_counter_destroy(&sbi->s_freeblocks_counter);
        percpu_counter_destroy(&sbi->s_freeinodes_counter);
@@ -1093,7 +1093,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
        }
        db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
                   EXT2_DESC_PER_BLOCK(sb);
-       sbi->s_group_desc = kmalloc_array(db_count,
+       sbi->s_group_desc = kvmalloc_array(db_count,
                                           sizeof(struct buffer_head *),
                                           GFP_KERNEL);
        if (sbi->s_group_desc == NULL) {
@@ -1219,7 +1219,7 @@ failed_mount2:
        for (i = 0; i < db_count; i++)
                brelse(sbi->s_group_desc[i]);
 failed_mount_group_desc:
-       kfree(sbi->s_group_desc);
+       kvfree(sbi->s_group_desc);
        kfree(sbi->s_debts);
 failed_mount:
        brelse(bh);