From: Jan Kara <jack@suse.cz>
Date: Wed, 14 Sep 2022 15:29:33 +0000 (+0200)
Subject: ext2: Use kvmalloc() for group descriptor array
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e7c7fbb9a8574ebd89cc05db49d806c7476863ad;p=linux.git

ext2: Use kvmalloc() for group descriptor array

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>
---

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index afb31af9302d7..03f2af98b1b48 100644
--- 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);
@@ -1092,7 +1092,7 @@ 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) {
@@ -1218,7 +1218,7 @@ 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);