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authorSasha Levin <sasha.levin@oracle.com>2015-01-28 15:30:43 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-06-06 08:21:09 -0700
commitd38e166a121b62819e13b32560ef8673c8467535 (patch)
tree514c218375c77409299748e2632556114884724a
parente8f61366d2ad418d3ff69aff398badbce5f03028 (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 999ff5c..d59712d 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;