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ext2: Check block size validity during mount

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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>
This commit is contained in:
Jan Kara 2023-03-01 11:59:39 +01:00
parent e9cd1d9a34
commit 62aeb94433
2 changed files with 8 additions and 0 deletions
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1
fs/ext2/ext2.h
View File

@ -180,6 +180,7 @@ static inline struct ext2_sb_info *EXT2_SB(struct super_block *sb)
#define EXT2_MIN_BLOCK_SIZE 1024
#define EXT2_MAX_BLOCK_SIZE 65536
#define EXT2_MIN_BLOCK_LOG_SIZE 10
#define EXT2_MAX_BLOCK_LOG_SIZE 16
#define EXT2_BLOCK_SIZE(s) ((s)->s_blocksize)
#define EXT2_ADDR_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / sizeof (__u32))
#define EXT2_BLOCK_SIZE_BITS(s) ((s)->s_blocksize_bits)

7
fs/ext2/super.c
View File

@ -945,6 +945,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
goto failed_mount;
}
if (le32_to_cpu(es->s_log_block_size) >
(EXT2_MAX_BLOCK_LOG_SIZE - BLOCK_SIZE_BITS)) {
ext2_msg(sb, KERN_ERR,
"Invalid log block size: %u",
le32_to_cpu(es->s_log_block_size));
goto failed_mount;
}
blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
if (test_opt(sb, DAX)) {