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ext3, ext4: avoid divide by zero

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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: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andries E. Brouwer 2007-12-17 16:19:55 -08:00 committed by Linus Torvalds
parent 9e2de407be
commit b47b6f38e5
2 changed files with 2 additions and 2 deletions
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2
fs/ext3/super.c
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@ -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)

2
fs/ext4/super.c
View file

@ -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)