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Tue, 17 Feb 2026 17:17:25 -0800 (PST) Received: from tux ([2601:7c0:c37c:4c00:e3a8:26f7:7e08:88e1]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-64c22c3565dsm5537096d50.0.2026.02.17.17.17.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Feb 2026 17:17:24 -0800 (PST) From: Ethan Tidmore To: akpm@linux-foundation.org Cc: lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, brauner@kernel.org, linux-kernel@vger.kernel.org, Ethan Tidmore Subject: [PATCH] ipc: Fix error pointer dereference Date: Tue, 17 Feb 2026 19:17:07 -0600 Message-ID: <20260218011707.581042-1-ethantidmore06@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The function shm_lock() can return an error pointer and is not checked for one. Add check for error pointer. Detected by Smatch: ipc/shm.c:1678 do_shmat() error: 'shp' dereferencing possible ERR_PTR() Fixes: 00c2bf85d8feb ("ipc: get rid of ipc_lock_down()") Signed-off-by: Ethan Tidmore --- ipc/shm.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/ipc/shm.c b/ipc/shm.c index e8c7d1924c50..d4554f4e7063 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1675,12 +1675,15 @@ long do_shmat(int shmid, char __user *shmaddr, int = shmflg, out_nattch: down_write(&shm_ids(ns).rwsem); shp =3D shm_lock(ns, shmid); - shp->shm_nattch--; + if (!IS_ERR(shp)) { + shp->shm_nattch--; + + if (shm_may_destroy(shp)) + shm_destroy(ns, shp); + else + shm_unlock(shp); + } =20 - if (shm_may_destroy(shp)) - shm_destroy(ns, shp); - else - shm_unlock(shp); up_write(&shm_ids(ns).rwsem); return err; =20 --=20 2.53.0