Commit b47b6f38 authored by Andries E. Brouwer's avatar Andries E. Brouwer Committed by Linus Torvalds
Browse files

ext3, ext4: avoid divide by zero 



As it turns out, the kernel divides by EXT3_INODES_PER_GROUP(s) when
mounting an ext3 filesystem.  If that number is zero, a crash follows.
Below a patch.

This crash was reported by Joeri de Ruiter, Carst Tankink and Pim Vullers.

Cc: <linux-ext4@vger.kernel.org>
Acked-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9e2de407

fs/ext3/super.c

+1 −1
Original line number Diff line number Diff line
@@ -1676,7 +1676,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent) 
	sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);

	sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);

	sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);

	if (EXT3_INODE_SIZE(sb) == 0)

	if (EXT3_INODE_SIZE(sb) == 0 || EXT3_INODES_PER_GROUP(sb) == 0)

		goto cantfind_ext3;

	sbi->s_inodes_per_block = blocksize / EXT3_INODE_SIZE(sb);

	if (sbi->s_inodes_per_block == 0)

fs/ext4/super.c

+1 −1
Original line number Diff line number Diff line
@@ -1797,7 +1797,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent) 
		sbi->s_desc_size = EXT4_MIN_DESC_SIZE;

	sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);

	sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);

	if (EXT4_INODE_SIZE(sb) == 0)

	if (EXT4_INODE_SIZE(sb) == 0 || EXT4_INODES_PER_GROUP(sb) == 0)

		goto cantfind_ext4;

	sbi->s_inodes_per_block = blocksize / EXT4_INODE_SIZE(sb);

	if (sbi->s_inodes_per_block == 0)

CRA Git | Maintained and supported by SUSTech CRA and CCSE