From e9fed2438a1ff475821864f906286dc58907f06b Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Wed, 3 Feb 2021 08:55:13 -0300 Subject: linux: Require /dev/shm as the shared memory file system Previously, glibc would pick an arbitrary tmpfs file system from /proc/mounts if /dev/shm was not available. This could lead to an unsuitable file system being picked for the backing storage for shm_open, sem_open, and related functions. This patch introduces a new function, __shm_get_name, which builds the file name under the appropriate (now hard-coded) directory. It is called from the various shm_* and sem_* function. Unlike the SHM_GET_NAME macro it replaces, the callers handle the return values and errno updates. shm-directory.c is moved directly into the posix subdirectory because it can be implemented directly using POSIX functionality. It resides in libc because it is needed by both librt and nptl/htl. In the sem_open implementation, tmpfname is initialized directly from a string constant. This happens to remove one alloca call. Checked on x86_64-linux-gnu. --- NEWS | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'NEWS') diff --git a/NEWS b/NEWS index 1ca12bc1a2..85e84fe536 100644 --- a/NEWS +++ b/NEWS @@ -20,7 +20,10 @@ Deprecated and removed features, and other changes affecting compatibility: Changes to build and runtime requirements: - [Add changes to build and runtime requirements here] +* On Linux, the shm_open, sem_open, and related functions now expect the + file shared memory file system to be mounted at /dev/shm. These functions + no longer search among the system's mount points for a suitable + replacement if /dev/shm is not available. Security related changes: -- cgit 1.4.1