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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Alexander Aring , Stefan Schmidt , Miquel Raynal , Remi Denis-Courmont , =?utf-8?B?UsOpbWk=?= Denis-Courmont , John Fastabend , Sabrina Dubroca , Shuah Khan , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-wpan@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@meta.com, =?utf-8?B?UsOpbWk=?= Denis-Courmont , Joe Damato Subject: Re: [PATCH net-next v3 4/7] phonet: pep: do not write beyond optlen in getsockopt Message-ID: References: <20260727-getsockopt_phase4-v3-0-e89627544639@debian.org> <20260727-getsockopt_phase4-v3-4-e89627544639@debian.org> 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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260727-getsockopt_phase4-v3-4-e89627544639@debian.org> On 07/27, Breno Leitao wrote: > pep_getsockopt() clamps the reported length to the caller's buffer with > min_t(), but then stores the value with put_user(val, (int __user *) > optval), which always writes sizeof(int) bytes. A getsockopt() call with > an optlen smaller than sizeof(int) thus reports the clamped length yet > writes a full int, one to three bytes past the user buffer. > > Write the value with copy_to_user() bounded by len, so at most optlen > bytes are copied, matching the length reported back to userspace. > > Fixes: 02a47617cdce ("Phonet: implement GPRS virtual interface over PEP socket") > Acked-by: Rémi Denis-Courmont > Reviewed-by: Joe Damato > Signed-off-by: Breno Leitao Acked-by: Stanislav Fomichev