net: hibmcge: fix double-free of tx skb on DMA mapping failure

If hbg_dma_map() fails, hbg_net_start_xmit() frees the skb, but buffer->skb
is left pointing to it. ring->ntu is not advanced, so the buffer is not
visible to the TX cleanup path.

A subsequent transmit normally overwrites the buffer. However, if the
interface is brought down first, hbg_ring_uninit() calls hbg_buffer_free().
It sees the stale pointer, attempts to unmap the failed mapping, and frees
the skb again.

Clear buffer->skb before freeing the skb in the error path, preventing
hbg_buffer_free() from treating it as an outstanding TX buffer.

Cc: stable+noautosel@kernel.org # untested fix to unlikely driver error path
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
Reviewed-by: Jijie Shao <shaojijie@huawei.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260710090527.58354-4-xuanqiang.luo@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions