diff options
| author | Li Qiang <liqiang6-s@360.cn> | 2016-10-17 14:13:58 +0200 |
|---|---|---|
| committer | Greg Kurz <groug@kaod.org> | 2016-10-17 14:13:58 +0200 |
| commit | ba42ebb863ab7d40adc79298422ed9596df8f73a (patch) | |
| tree | 33cc7c9847dd8fb6dc3db97ddd5ac5f590c93600 | |
| parent | ad728364e3916e1159ee94e5cd82b7a9c81d2dcc (diff) | |
9pfs: allocate space for guest originated empty strings
If a guest sends an empty string paramater to any 9P operation, the current
code unmarshals it into a V9fsString equal to { .size = 0, .data = NULL }.
This is unfortunate because it can cause NULL pointer dereference to happen
at various locations in the 9pfs code. And we don't want to check str->data
everywhere we pass it to strcmp() or any other function which expects a
dereferenceable pointer.
This patch enforces the allocation of genuine C empty strings instead, so
callers don't have to bother.
Out of all v9fs_iov_vunmarshal() users, only v9fs_xattrwalk() checks if
the returned string is empty. It now uses v9fs_string_size() since
name.data cannot be NULL anymore.
Signed-off-by: Li Qiang <liqiang6-s@360.cn>
[groug, rewritten title and changelog,
fix empty string check in v9fs_xattrwalk()]
Signed-off-by: Greg Kurz <groug@kaod.org>
| -rw-r--r-- | fsdev/9p-iov-marshal.c | 2 | ||||
| -rw-r--r-- | hw/9pfs/9p.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/fsdev/9p-iov-marshal.c b/fsdev/9p-iov-marshal.c index 663cad5429..1d16f8df4b 100644 --- a/fsdev/9p-iov-marshal.c +++ b/fsdev/9p-iov-marshal.c @@ -125,7 +125,7 @@ ssize_t v9fs_iov_vunmarshal(struct iovec *out_sg, int out_num, size_t offset, str->data = g_malloc(str->size + 1); copied = v9fs_unpack(str->data, out_sg, out_num, offset, str->size); - if (copied > 0) { + if (copied >= 0) { str->data[str->size] = 0; } else { v9fs_string_free(str); diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 119ee58496..39a7e1d52d 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -3174,7 +3174,7 @@ static void v9fs_xattrwalk(void *opaque) goto out; } v9fs_path_copy(&xattr_fidp->path, &file_fidp->path); - if (name.data == NULL) { + if (!v9fs_string_size(&name)) { /* * listxattr request. Get the size first */ |