From 2b2c8aafce9d80f9d58652643538f4d58e82b856 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Fri, 13 Mar 2020 16:27:10 -0400 Subject: fix corrupt sysvipc timestamps on 32-bit archs with old kernels kernel commit 4693916846269d633a3664586650dbfac2c5562f (first included in release v4.14) silently fixed a bug whereby the reserved space (which was later used for high bits of time) in IPC_STAT structures was left untouched rather than zeroed. this means that a caller that wants to read the high bits needs to pre-zero the memory. since it's not clear that these operations are permitted to modify the destination buffer on failure, use a temp buffer and copy back to the caller's buffer on success. --- src/ipc/shmctl.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'src/ipc/shmctl.c') diff --git a/src/ipc/shmctl.c b/src/ipc/shmctl.c index de3ce9d4..1c9f78c2 100644 --- a/src/ipc/shmctl.c +++ b/src/ipc/shmctl.c @@ -9,6 +9,14 @@ int shmctl(int id, int cmd, struct shmid_ds *buf) { +#if IPC_TIME64 + struct shmid_ds out, *orig; + if (cmd&IPC_TIME64) { + out = (struct shmid_ds){0}; + orig = buf; + buf = &out; + } +#endif #ifdef SYSCALL_IPC_BROKEN_MODE struct shmid_ds tmp; if (cmd == IPC_SET) { @@ -32,6 +40,8 @@ int shmctl(int id, int cmd, struct shmid_ds *buf) #endif #if IPC_TIME64 if (r >= 0 && (cmd&IPC_TIME64)) { + buf = orig; + *buf = out; IPC_HILO(buf, shm_atime); IPC_HILO(buf, shm_dtime); IPC_HILO(buf, shm_ctime); -- cgit v1.2.1