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ext2: Check block size validity during mount 

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)) {