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[83.28.44.212]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b79f4459378sm754765966b.6.2025.12.06.15.16.12 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Sat, 06 Dec 2025 15:16:13 -0800 (PST) Date: Sun, 7 Dec 2025 00:16:08 +0100 From: Michal Pecio To: Bitterblue Smith Cc: Ping-Ke Shih , Zenm Chen , "gustavo@embeddedor.com" , "Jes.Sorensen@gmail.com" , "gustavoars@kernel.org" , "linux-hardening@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-wireless@vger.kernel.org" , linux-usb@vger.kernel.org Subject: Re: [PATCH][next] wifi: rtl8xxxu: Avoid -Wflex-array-member-not-at-end warnings Message-ID: <20251207001608.1f6940bf.michal.pecio@gmail.com> In-Reply-To: <44c9c325-14a8-4391-adce-4bbe8c68b446@gmail.com> References: <20251121111132.4435-1-zenmchen@gmail.com> <475b4336-eed0-4fae-848f-aae26f109606@gmail.com> <44c9c325-14a8-4391-adce-4bbe8c68b446@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi, > >> I got something. In my case everything seemed fine until I > >> unplugged the wifi adapter. And then the system still worked for a > >> few minutes before it froze. Sounds like memory corruption. > > Zenm and I tested below changes which can also reproduce the > > symptom, so I wonder driver might assume urb is the first member of > > struct, but unfortunately I can't find that. That's what it seems to be doing, because it uses usb_init_urb() on urbs embedded in some struct and then usb_free_urb(). If you look what usb_free_urb() does, it decrements refcount and attempts to free urb. But here urb is a member of a larger struct, so I guess the whole struct is freed (and this was either intentional or a bug that didn't happen to blow up yet). Now a bogus address is being passed to kfree() and things go boom. Or at least that's my first guess after spending a few minutes. But that's the direction I would be looking at. Regards, Michal