staging: rtl8712: remove unnecessary alignment of pxmitpriv->pxmitbuf

This driver wants pxmitpriv->pxmitbuf to be 4-byte aligned. This is ensured
by allocating 4 more bytes than required with kmalloc(), then do the
p = p + 4 - (p & 3) trick to make sure the pointer is 4-byte aligned.

This is unnecessary. Pointers from kmalloc() are already at least
8-byte-aligned.

Remove this alignment trick to simplify the code, and also to stop wasting
4 extra bytes of dynamic memory allocator.

This also gets rid of a (false) warning from kmemleak. This 4-byte-aligned
buffer is used to store pointers from kmalloc(). For 64-bit platforms,
pointer size is 8 bytes and kmemleak only scans for pointers in 8-byte
blocks, thus it misses the pointers stored in this 4-byte-aligned buffer
and thinks that these pointers have been leaked. This is just a false
warning, not a real problem. But still, it would be nice to get rid of
these warnings.

Reported-and-tested-by: syzbot+83763e624cfec6b462cb@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-staging/000000000000809328060a8a4c1c@google.com
Signed-off-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20240525073229.4144612-1-namcao@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/rtl8712/rtl871x_xmit.c b/drivers/staging/rtl8712/rtl871x_xmit.c
index 6353dbe554d3a147ece6e225fae2d3519a2883cb..408616e9afcfffe134e2da881cac587ae6e2b0f3 100644 (file)
--- a/drivers/staging/rtl8712/rtl871x_xmit.c
+++ b/drivers/staging/rtl8712/rtl871x_xmit.c
@@ -117,12 +117,9 @@ int _r8712_init_xmit_priv(struct xmit_priv *pxmitpriv,
        /*init xmit_buf*/
        _init_queue(&pxmitpriv->free_xmitbuf_queue);
        _init_queue(&pxmitpriv->pending_xmitbuf_queue);
-       pxmitpriv->pallocated_xmitbuf =
-               kmalloc(NR_XMITBUFF * sizeof(struct xmit_buf) + 4, GFP_ATOMIC);
-       if (!pxmitpriv->pallocated_xmitbuf)
+       pxmitpriv->pxmitbuf = kmalloc(NR_XMITBUFF * sizeof(struct xmit_buf), GFP_ATOMIC);
+       if (!pxmitpriv->pxmitbuf)
                goto clean_up_frame_buf;
-       pxmitpriv->pxmitbuf = pxmitpriv->pallocated_xmitbuf + 4 -
-                             ((addr_t)(pxmitpriv->pallocated_xmitbuf) & 3);
        pxmitbuf = (struct xmit_buf *)pxmitpriv->pxmitbuf;
        for (i = 0; i < NR_XMITBUFF; i++) {
                INIT_LIST_HEAD(&pxmitbuf->list);
@@ -165,8 +162,8 @@ clean_up_alloc_buf:
                for (k = 0; k < 8; k++)         /* delete xmit urb's */
                        usb_free_urb(pxmitbuf->pxmit_urb[k]);
        }
-       kfree(pxmitpriv->pallocated_xmitbuf);
-       pxmitpriv->pallocated_xmitbuf = NULL;
+       kfree(pxmitpriv->pxmitbuf);
+       pxmitpriv->pxmitbuf = NULL;
 clean_up_frame_buf:
        kfree(pxmitpriv->pallocated_frame_buf);
        pxmitpriv->pallocated_frame_buf = NULL;
@@ -193,7 +190,7 @@ void _free_xmit_priv(struct xmit_priv *pxmitpriv)
                pxmitbuf++;
        }
        kfree(pxmitpriv->pallocated_frame_buf);
-       kfree(pxmitpriv->pallocated_xmitbuf);
+       kfree(pxmitpriv->pxmitbuf);
        free_hwxmits(padapter);
 }
 

diff --git a/drivers/staging/rtl8712/rtl871x_xmit.h b/drivers/staging/rtl8712/rtl871x_xmit.h
index cdcbc87a3cadeb8d7ed442f1a1c53b086f4c8c83..784172c385e37c4dc182f15351784f288116a322 100644 (file)
--- a/drivers/staging/rtl8712/rtl871x_xmit.h
+++ b/drivers/staging/rtl8712/rtl871x_xmit.h
@@ -244,7 +244,6 @@ struct      xmit_priv {
        int cmdseq;
        struct  __queue free_xmitbuf_queue;
        struct  __queue pending_xmitbuf_queue;
-       u8 *pallocated_xmitbuf;
        u8 *pxmitbuf;
        uint free_xmitbuf_cnt;
 };