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 fd855574ef0928cb809319579c93fc9e783747fa..02d82f8fe85d9a8f5928d0596e3b5f8ed089c560 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);
@@ -1080,7 +1080,7 @@ 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) {
@@ -1206,7 +1206,7 @@ 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);