On 12/12/22 16:29, Niel Fourie wrote:
In eth_halt(), reread and revalidate priv after calling stop(),
as it may have been freed, leaving a dangling pointer.

In the ethernet gadget implementation, the gadget device gets
probed during start() and removed during stop(), which includes
freeing `uclass_priv_` to which `priv` is pointing. Writing to
`priv` after stop() may corrupt the `fd` member of `struct
malloc_chunk`, which represents the freed block, and could cause
hard-to-debug crashes on subsequent calls to malloc()/free().

Signed-off-by: Niel Fourie <lu...@denx.de>
Cc: Ramon Fried <rfried....@gmail.com>
Cc: Marek Vasut <ma...@denx.de>
Cc: Lukasz Majewski <lu...@denx.de>
---
Changes for v2:
- Revalidate priv instead of changing state before stop()
- Added explanational comment

This patch my be dropped if the patch which addresses the root cause
("usb: gadget: ether: split start/stop from init/halt") is accepted.

  net/eth-uclass.c | 5 ++++-
  1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/eth-uclass.c b/net/eth-uclass.c
index f41da4b37b3..7d5783b5cab 100644
--- a/net/eth-uclass.c
+++ b/net/eth-uclass.c
@@ -341,8 +341,11 @@ void eth_halt(void)
        priv = dev_get_uclass_priv(current);
        if (!priv || !priv->running)
                return;
-
        eth_get_ops(current)->stop(current);
+       /* Ethernet gadget frees priv during stop, workaround until fixed... */
+       priv = dev_get_uclass_priv(current);
+       if (!priv || !priv->running)
+               return;

Is this fixed by the second patch in this series ?
If so, drop this patch.

Reply via email to