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authorTheodore Ts'o <tytso@mit.edu>2018-07-12 19:08:05 -0400
committerTheodore Ts'o <tytso@mit.edu>2018-07-12 19:08:05 -0400
commit8d5a803c6a6ce4ec258e31f76059ea5153ba46ef (patch)
tree1efe5596c31c67ad7a80006b6930ebe66373ed31 /fs/ext4
parent362eca70b53389bddf3143fe20f53dcce2cfdf61 (diff)
downloadlinux-8d5a803c6a6ce4ec258e31f76059ea5153ba46ef.tar.bz2
ext4: check for allocation block validity with block group locked
With commit 044e6e3d74a3: "ext4: don't update checksum of new initialized bitmaps" the buffer valid bit will get set without actually setting up the checksum for the allocation bitmap, since the checksum will get calculated once we actually allocate an inode or block. If we are doing this, then we need to (re-)check the verified bit after we take the block group lock. Otherwise, we could race with another process reading and verifying the bitmap, which would then complain about the checksum being invalid. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1780137 Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/balloc.c3
-rw-r--r--fs/ext4/ialloc.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index e68cefe08261..aa52d87985aa 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -368,6 +368,8 @@ static int ext4_validate_block_bitmap(struct super_block *sb,
return -EFSCORRUPTED;
ext4_lock_group(sb, block_group);
+ if (buffer_verified(bh))
+ goto verified;
if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
desc, bh))) {
ext4_unlock_group(sb, block_group);
@@ -386,6 +388,7 @@ static int ext4_validate_block_bitmap(struct super_block *sb,
return -EFSCORRUPTED;
}
set_buffer_verified(bh);
+verified:
ext4_unlock_group(sb, block_group);
return 0;
}
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index fb83750c1a14..e9d8e2667ab5 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -90,6 +90,8 @@ static int ext4_validate_inode_bitmap(struct super_block *sb,
return -EFSCORRUPTED;
ext4_lock_group(sb, block_group);
+ if (buffer_verified(bh))
+ goto verified;
blk = ext4_inode_bitmap(sb, desc);
if (!ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
EXT4_INODES_PER_GROUP(sb) / 8)) {
@@ -101,6 +103,7 @@ static int ext4_validate_inode_bitmap(struct super_block *sb,
return -EFSBADCRC;
}
set_buffer_verified(bh);
+verified:
ext4_unlock_group(sb, block_group);
return 0;
}