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Mon, 30 Jun 2025 07:36:11 -0700 (PDT) From: Petr Pavlu To: Luis Chamberlain , Petr Pavlu , Sami Tolvanen , Daniel Gomez Cc: linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/5] module: Prevent silent truncation of module name in delete_module(2) Date: Mon, 30 Jun 2025 16:32:32 +0200 Message-ID: <20250630143535.267745-2-petr.pavlu@suse.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250630143535.267745-1-petr.pavlu@suse.com> References: <20250630143535.267745-1-petr.pavlu@suse.com> 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" Passing a module name longer than MODULE_NAME_LEN to the delete_module syscall results in its silent truncation. This really isn't much of a problem in practice, but it could theoretically lead to the removal of an incorrect module. It is more sensible to return ENAMETOOLONG or ENOENT in such a case. Update the syscall to return ENOENT, as documented in the delete_module(2) man page to mean "No module by that name exists." This is appropriate because a module with a name longer than MODULE_NAME_LEN cannot be loaded in the first place. Signed-off-by: Petr Pavlu Reviewed-by: Daniel Gomez --- kernel/module/main.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 413ac6ea3702..933a9854cb7d 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -751,14 +751,16 @@ SYSCALL_DEFINE2(delete_module, const char __user *, n= ame_user, struct module *mod; char name[MODULE_NAME_LEN]; char buf[MODULE_FLAGS_BUF_SIZE]; - int ret, forced =3D 0; + int ret, len, forced =3D 0; =20 if (!capable(CAP_SYS_MODULE) || modules_disabled) return -EPERM; =20 - if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0) - return -EFAULT; - name[MODULE_NAME_LEN-1] =3D '\0'; + len =3D strncpy_from_user(name, name_user, MODULE_NAME_LEN); + if (len =3D=3D 0 || len =3D=3D MODULE_NAME_LEN) + return -ENOENT; + if (len < 0) + return len; =20 audit_log_kern_module(name); =20 --=20 2.49.0