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| 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 /fsdev | |
| parent | ad728364e3916e1159ee94e5cd82b7a9c81d2dcc (diff) | |
| download | qemu-ba42ebb863ab7d40adc79298422ed9596df8f73a.zip qemu-ba42ebb863ab7d40adc79298422ed9596df8f73a.tar.gz qemu-ba42ebb863ab7d40adc79298422ed9596df8f73a.tar.bz2 | |
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>
Diffstat (limited to 'fsdev')
| -rw-r--r-- | fsdev/9p-iov-marshal.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fsdev/9p-iov-marshal.c b/fsdev/9p-iov-marshal.c index 663cad5..1d16f8d 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); |