From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [BUG] rtl8192se: panic accessing unmapped memory in skb Date: Sun, 21 Dec 2014 11:25:16 -0600 Message-ID: <20141221172516.GA12784@zzz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Larry.Finger-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: Content-Disposition: inline Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org Hi, I have a RTL8192SE wireless card, attached via PCI. Usually it works with no issues, but I recently had a kernel panic occur in the rtl8192se driver. The kernel version is 3.18. Based on my analysis of the panic dump, the panic was caused by a memory access violation in this block of code in rtl92se_rx_query_desc(): if (stats->decrypted) { hdr = (struct ieee80211_hdr *)(skb->data + stats->rx_drvinfo_size + stats->rx_bufshift); if ((_ieee80211_is_robust_mgmt_frame(hdr)) && (ieee80211_has_protected(hdr->frame_control))) rx_status->flag &= ~RX_FLAG_DECRYPTED; else rx_status->flag |= RX_FLAG_DECRYPTED; } Specifically, the violation occurred the first time hdr->frame_control was accessed, as part of _ieee80211_is_robust_mgmt_frame(). The panic occurred when the system was under heavy filesystem load but seemingly is not easily reproducible. There was recently a NULL check that was removed from this exact place in the code, but it was certainly useless. Instead, what's much more suspect to me is that inside _rtl_pci_rx_interrupt(), there is no error checking of the return value of _rtl_pci_init_one_rxdesc(), which might fail if the skb couldn't be allocated. I am wondering if this could be causing the problem. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html