diff options
| author | David Sterba <dsterba@suse.com> | 2015-11-09 13:44:45 +0300 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2016-01-05 15:08:26 +0300 |
| commit | 8b867d859e1c31fd293096f0fddc24fce01ff41b (patch) | |
| tree | 8a23500b3dda1223ce7b167ee993d03eef3c791b /fs | |
| parent | 8798684ae49137515888fa3fc39591c3e339288e (diff) | |
| download | linux-8b867d859e1c31fd293096f0fddc24fce01ff41b.tar.xz | |
btrfs: fix signed overflows in btrfs_sync_file
commit 9dcbeed4d7e11e1dcf5e55475de3754f0855d1c2 upstream.
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>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
[ kamal: backport to 3.13-stable: use len in both btrfs_wait_ordered_range
calls, like
b659ef0 Btrfs: avoid syncing log in the fast fsync path when not necessary ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/file.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 7a71c7885835..8d60cf519578 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1868,7 +1868,13 @@ 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; + 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); /* @@ -1896,7 +1902,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags); if (full_sync) { - ret = btrfs_wait_ordered_range(inode, start, end - start + 1); + ret = btrfs_wait_ordered_range(inode, start, len); if (ret) { mutex_unlock(&inode->i_mutex); goto out; @@ -2001,8 +2007,7 @@ 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; |