ext2: Check block size validity during mount
[ Upstream commit 62aeb94433
]
Check that log of block size stored in the superblock has sensible
value. Otherwise the shift computing the block size can overflow leading
to undefined behavior.
Reported-by: syzbot+4fec412f59eba8c01b77@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -180,6 +180,7 @@ static inline struct ext2_sb_info *EXT2_SB(struct super_block *sb)
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#define EXT2_MIN_BLOCK_SIZE 1024
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#define EXT2_MAX_BLOCK_SIZE 4096
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#define EXT2_MIN_BLOCK_LOG_SIZE 10
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#define EXT2_MAX_BLOCK_LOG_SIZE 16
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#define EXT2_BLOCK_SIZE(s) ((s)->s_blocksize)
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#define EXT2_ADDR_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / sizeof (__u32))
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#define EXT2_BLOCK_SIZE_BITS(s) ((s)->s_blocksize_bits)
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@ -945,6 +945,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
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goto failed_mount;
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}
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if (le32_to_cpu(es->s_log_block_size) >
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(EXT2_MAX_BLOCK_LOG_SIZE - BLOCK_SIZE_BITS)) {
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ext2_msg(sb, KERN_ERR,
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"Invalid log block size: %u",
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le32_to_cpu(es->s_log_block_size));
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goto failed_mount;
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}
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blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
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if (test_opt(sb, DAX)) {
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