diff options
| author | David Sterba | 2015-11-09 11:44:45 +0100 |
|---|---|---|
| committer | Chris Mason | 2015-11-25 05:19:50 -0800 |
| commit | 9dcbeed4d7e11e1dcf5e55475de3754f0855d1c2 (patch) | |
| tree | 4f1418f234da7f11144e2d512b681f004926440a /fs | |
| parent | d5f2e33b92b10b8007be50b570a27e9bacfb4c3a (diff) | |
btrfs: fix signed overflows in btrfs_sync_file
The calculation of range length in btrfs_sync_file leads to signed
overflow. This was caught by PaX gcc SIZE_OVERFLOW plugin.
https://forums.grsecurity.net/viewtopic.php?f=1&t=4284
The fsync call passes 0 and LLONG_MAX, the range length does not fit to
loff_t and overflows, but the value is converted to u64 so it silently
works as expected.
The minimal fix is a typecast to u64, switching functions to take
(start, end) instead of (start, len) would be more intrusive.
Coccinelle script found that there's one more opencoded calculation of
the length.
<smpl>
@@
loff_t start, end;
@@
* end - start
</smpl>
CC: stable@vger.kernel.org
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/file.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 3009d4536d38..8eb1f3c1b647 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1882,8 +1882,13 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) struct btrfs_log_ctx ctx; int ret = 0; bool full_sync = 0; - const u64 len = end - start + 1; + u64 len; + /* + * The range length can be represented by u64, we have to do the typecasts + * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync() + */ + len = (u64)end - (u64)start + 1; trace_btrfs_sync_file(file, datasync); /* @@ -2071,8 +2076,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) } } if (!full_sync) { - ret = btrfs_wait_ordered_range(inode, start, - end - start + 1); + ret = btrfs_wait_ordered_range(inode, start, len); if (ret) { btrfs_end_transaction(trans, root); goto out; |