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authorTheodore Ts'o <tytso@mit.edu>2016-11-18 21:37:47 +0300
committerTheodore Ts'o <tytso@mit.edu>2016-11-18 21:37:47 +0300
commitc48ae41bafe31e9a66d8be2ced4e42a6b57fa814 (patch)
tree5bce12d4855399ea72f2b89dc108ab4e1c45a556 /fs/ext4
parentcd6bb35bf7f6d7d922509bf50265383a0ceabe96 (diff)
downloadlinux-c48ae41bafe31e9a66d8be2ced4e42a6b57fa814.tar.xz
ext4: add sanity checking to count_overhead()
The commit "ext4: sanity check the block and cluster size at mount time" should prevent any problems, but in case the superblock is modified while the file system is mounted, add an extra safety check to make sure we won't overrun the allocated buffer. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/super.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 689c02df1af4..2d8a49d74f56 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3195,10 +3195,15 @@ static int count_overhead(struct super_block *sb, ext4_group_t grp,
ext4_set_bit(s++, buf);
count++;
}
- for (j = ext4_bg_num_gdb(sb, grp); j > 0; j--) {
- ext4_set_bit(EXT4_B2C(sbi, s++), buf);
- count++;
+ j = ext4_bg_num_gdb(sb, grp);
+ if (s + j > EXT4_BLOCKS_PER_GROUP(sb)) {
+ ext4_error(sb, "Invalid number of block group "
+ "descriptor blocks: %d", j);
+ j = EXT4_BLOCKS_PER_GROUP(sb) - s;
}
+ count += j;
+ for (; j > 0; j--)
+ ext4_set_bit(EXT4_B2C(sbi, s++), buf);
}
if (!count)
return 0;