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authorJ. Bruce Fields <bfields@redhat.com>2014-02-03 21:13:08 +0400
committerJeff Layton <jlayton@redhat.com>2014-03-31 16:24:42 +0400
commitef12e72a01f3022c55e5a8e0fa1caebdc7efcfce (patch)
tree54209e0731082ff7e2a36ede9b045d415132134e /fs/locks.c
parent8c3cac5e6a85f03602ffe09c44f14418699e31ec (diff)
downloadlinux-ef12e72a01f3022c55e5a8e0fa1caebdc7efcfce.tar.xz
locks: fix posix lock range overflow handling
In the 32-bit case fcntl assigns the 64-bit f_pos and i_size to a 32-bit off_t. The existing range checks also seem to depend on signed arithmetic wrapping when it overflows. In practice maybe that works, but we can be more careful. That also allows us to make a more reliable distinction between -EINVAL and -EOVERFLOW. Note that in the 32-bit case SEEK_CUR or SEEK_END might allow the caller to set a lock with starting point no longer representable as a 32-bit value. We could return -EOVERFLOW in such cases, but the locks code is capable of handling such ranges, so we choose to be lenient here. The only problem is that subsequent GETLK calls on such a lock will fail with EOVERFLOW. While we're here, do some cleanup including consolidating code for the flock and flock64 cases. Signed-off-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'fs/locks.c')
-rw-r--r--fs/locks.c100
1 files changed, 32 insertions, 68 deletions
diff --git a/fs/locks.c b/fs/locks.c
index dd309333afc9..b49e853a9c7b 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -344,48 +344,43 @@ static int assign_type(struct file_lock *fl, long type)
return 0;
}
-/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
- * style lock.
- */
-static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
- struct flock *l)
+static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
+ struct flock64 *l)
{
- off_t start, end;
-
switch (l->l_whence) {
case SEEK_SET:
- start = 0;
+ fl->fl_start = 0;
break;
case SEEK_CUR:
- start = filp->f_pos;
+ fl->fl_start = filp->f_pos;
break;
case SEEK_END:
- start = i_size_read(file_inode(filp));
+ fl->fl_start = i_size_read(file_inode(filp));
break;
default:
return -EINVAL;
}
+ if (l->l_start > OFFSET_MAX - fl->fl_start)
+ return -EOVERFLOW;
+ fl->fl_start += l->l_start;
+ if (fl->fl_start < 0)
+ return -EINVAL;
/* POSIX-1996 leaves the case l->l_len < 0 undefined;
POSIX-2001 defines it. */
- start += l->l_start;
- if (start < 0)
- return -EINVAL;
- fl->fl_end = OFFSET_MAX;
if (l->l_len > 0) {
- end = start + l->l_len - 1;
- fl->fl_end = end;
+ if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
+ return -EOVERFLOW;
+ fl->fl_end = fl->fl_start + l->l_len - 1;
+
} else if (l->l_len < 0) {
- end = start - 1;
- fl->fl_end = end;
- start += l->l_len;
- if (start < 0)
+ if (fl->fl_start + l->l_len < 0)
return -EINVAL;
- }
- fl->fl_start = start; /* we record the absolute position */
- if (fl->fl_end < fl->fl_start)
- return -EOVERFLOW;
-
+ fl->fl_end = fl->fl_start - 1;
+ fl->fl_start += l->l_len;
+ } else
+ fl->fl_end = OFFSET_MAX;
+
fl->fl_owner = current->files;
fl->fl_pid = current->tgid;
fl->fl_file = filp;
@@ -396,52 +391,21 @@ static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
return assign_type(fl, l->l_type);
}
-#if BITS_PER_LONG == 32
-static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
- struct flock64 *l)
+/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
+ * style lock.
+ */
+static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
+ struct flock *l)
{
- loff_t start;
-
- switch (l->l_whence) {
- case SEEK_SET:
- start = 0;
- break;
- case SEEK_CUR:
- start = filp->f_pos;
- break;
- case SEEK_END:
- start = i_size_read(file_inode(filp));
- break;
- default:
- return -EINVAL;
- }
+ struct flock64 ll = {
+ .l_type = l->l_type,
+ .l_whence = l->l_whence,
+ .l_start = l->l_start,
+ .l_len = l->l_len,
+ };
- start += l->l_start;
- if (start < 0)
- return -EINVAL;
- fl->fl_end = OFFSET_MAX;
- if (l->l_len > 0) {
- fl->fl_end = start + l->l_len - 1;
- } else if (l->l_len < 0) {
- fl->fl_end = start - 1;
- start += l->l_len;
- if (start < 0)
- return -EINVAL;
- }
- fl->fl_start = start; /* we record the absolute position */
- if (fl->fl_end < fl->fl_start)
- return -EOVERFLOW;
-
- fl->fl_owner = current->files;
- fl->fl_pid = current->tgid;
- fl->fl_file = filp;
- fl->fl_flags = FL_POSIX;
- fl->fl_ops = NULL;
- fl->fl_lmops = NULL;
-
- return assign_type(fl, l->l_type);
+ return flock64_to_posix_lock(filp, fl, &ll);
}
-#endif
/* default lease lock manager operations */
static void lease_break_callback(struct file_lock *fl)