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authorTheodore Ts'o <tytso@mit.edu>2018-07-12 19:08:05 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-08-03 07:50:43 +0200
commitdc1b4b710fbef5f8f5a41efe35368e9dd07e71cb (patch)
tree9b4536f5cebb82ea87ba77ff67623d9cdf8cc781
parentcdcbe750acd6cd1e083189c2a50810eeb59f057a (diff)
ext4: check for allocation block validity with block group locked
commit 8d5a803c6a6ce4ec258e31f76059ea5153ba46ef upstream. 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 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 9c9eafd6bd76..70266a3355dc 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -379,6 +379,8 @@ 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);
@@ -401,6 +403,7 @@ 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 95341bc2b3b7..e38340b218a0 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -91,6 +91,8 @@ 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)) {
@@ -108,6 +110,7 @@ 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;
}