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fix corrupt sysvipc timestamps on 32-bit archs with old kernels

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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.
This commit is contained in:
Rich Felker 2020-03-13 16:27:10 -04:00
parent 5db475f0b9
commit 2b2c8aafce
3 changed files with 30 additions and 0 deletions
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10
src/ipc/msgctl.c
View File

@ -9,6 +9,14 @@
int msgctl(int q, int cmd, struct msqid_ds *buf)
{
#if IPC_TIME64
struct msqid_ds out, *orig;
if (cmd&IPC_TIME64) {
out = (struct msqid_ds){0};
orig = buf;
buf = &out;
}
#endif
#ifdef SYSCALL_IPC_BROKEN_MODE
struct msqid_ds tmp;
if (cmd == IPC_SET) {
@ -32,6 +40,8 @@ int msgctl(int q, int cmd, struct msqid_ds *buf)
#endif
#if IPC_TIME64
if (r >= 0 && (cmd&IPC_TIME64)) {
buf = orig;
*buf = out;
IPC_HILO(buf, msg_stime);
IPC_HILO(buf, msg_rtime);
IPC_HILO(buf, msg_ctime);

10
src/ipc/semctl.c
View File

@ -28,6 +28,14 @@ int semctl(int id, int num, int cmd, ...)
arg = va_arg(ap, union semun);
va_end(ap);
}
#if IPC_TIME64
struct semid_ds out, *orig;
if (cmd&IPC_TIME64) {
out = (struct semid_ds){0};
orig = arg.buf;
arg.buf = &out;
}
#endif
#ifdef SYSCALL_IPC_BROKEN_MODE
struct semid_ds tmp;
if (cmd == IPC_SET) {
@ -51,6 +59,8 @@ int semctl(int id, int num, int cmd, ...)
#endif
#if IPC_TIME64
if (r >= 0 && (cmd&IPC_TIME64)) {
arg.buf = orig;
*arg.buf = out;
IPC_HILO(arg.buf, sem_otime);
IPC_HILO(arg.buf, sem_ctime);
}

10
src/ipc/shmctl.c
View File

@ -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);