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authorSasha Levin <sasha.levin@oracle.com>2015-01-28 15:30:43 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-06-05 23:20:00 -0700
commitfe023f735b36f809b4d740e86f15658a2852fc09 (patch)
tree19b8f378a13501e31132c9b1c1ebcbb2d6d304c5
parent92c934b10ec3ed9db375161829d715892c9f4f99 (diff)
vfs: read file_handle only once in handle_to_path
commit 161f873b89136eb1e69477c847d5a5033239d9ba upstream. We used to read file_handle twice. Once to get the amount of extra bytes, and once to fetch the entire structure. This may be problematic since we do size verifications only after the first read, so if the number of extra bytes changes in userspace between the first and second calls, we'll have an incoherent view of file_handle. Instead, read the constant size once, and copy that over to the final structure without having to re-read it again. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/fhandle.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 999ff5c3cab0..d59712dfa3e7 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -195,8 +195,9 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
goto out_err;
}
/* copy the full handle */
- if (copy_from_user(handle, ufh,
- sizeof(struct file_handle) +
+ *handle = f_handle;
+ if (copy_from_user(&handle->f_handle,
+ &ufh->f_handle,
f_handle.handle_bytes)) {
retval = -EFAULT;
goto out_handle;