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[34.16.174.112]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c82e7ff304asm2871640a12.12.2026.05.17.21.59.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 17 May 2026 21:59:13 -0700 (PDT) Date: Mon, 18 May 2026 04:59:10 +0000 From: Carlos Llamas To: Andrii Nakryiko Cc: mykyta.yatsenko5@gmail.com, Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , kernel-team@android.com, linux-kernel@vger.kernel.org, Mykyta Yatsenko , "open list:BPF [GENERAL] (Safe Dynamic Programs and Tools)" Subject: Re: [PATCH v2] libbpf: fix UAF in strset__add_str() Message-ID: References: <89d34016-cf82-4beb-989c-e4fc2e3cd29e@gmail.com> <20260515044759.2863546-1-cmllamas@google.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-Disposition: inline In-Reply-To: On Fri, May 15, 2026 at 03:08:47PM -0700, Andrii Nakryiko wrote: > I agree that this is a usability problem, but I'd handle it by > recalculating s pointer to correct one if it happens to be coming from > invalidated strs_data. Something along the lines of: > > const char *old_data = set->strs_data; > size_t old_data_len = set->strs_data_len; > > p = strset_add_str_mem(...); > if (!p) > return -ENOMEM; > > if (p != old_data && s >= old_data && s < old_data + old_data_len) > s = p + (s - old_data); > > > At this point s will be correct even if it was invalidated. > > pw-bot: cr Oh right, that totally works. I've tested the changes and will send a new patch. Obviously 'p' was meant to be 'set->strs_data' in the check. Thanks, -- Carlos Llamas