hardlink: fix memory corruption in read buffers

The size of the eq->buf_a and eq->buf_b buffers depends on the
readsize setting. This setting is modified by ul_fileeq_set_size(), so
the buffers need to be resized accordingly. Deallocating is
sufficient, as they will be allocated later with the correct size.

Addresses: https://github.com/util-linux/util-linux/issues/3330
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/lib/fileeq.c b/lib/fileeq.c
index d0ba77cc3d7cdc1e9c771f08000913d55d5b4f7d..1495636772b7410a719966375813736e3466bf56 100644 (file)
--- a/lib/fileeq.c
+++ b/lib/fileeq.c
@@ -183,6 +183,13 @@ int ul_fileeq_init(struct ul_fileeq *eq, const char *method)
        return 0;
 }
 
+static void reset_fileeq_bufs(struct ul_fileeq *eq)
+{
+       free(eq->buf_a);
+       free(eq->buf_b);
+       eq->buf_last = eq->buf_a = eq->buf_b = NULL;
+}
+
 void ul_fileeq_deinit(struct ul_fileeq *eq)
 {
        if (!eq)
@@ -192,8 +199,7 @@ void ul_fileeq_deinit(struct ul_fileeq *eq)
 #ifdef USE_FILEEQ_CRYPTOAPI
        deinit_crypto_api(eq);
 #endif
-       free(eq->buf_a);
-       free(eq->buf_b);
+       reset_fileeq_bufs(eq);
 }
 
 void ul_fileeq_data_close_file(struct ul_fileeq_data *data)
@@ -281,6 +287,9 @@ size_t ul_fileeq_set_size(struct ul_fileeq *eq, uint64_t filesiz,
 
        DBG(EQ, ul_debugobj(eq, "set sizes: filesiz=%ju, maxblocks=%" PRIu64 ", readsiz=%zu",
                                eq->filesiz, eq->blocksmax, eq->readsiz));
+
+       reset_fileeq_bufs(eq);
+
        return eq->blocksmax;
 }