path: root/src/ipc/semctl.c
diff options
authorRich Felker <>2018-06-20 00:07:09 -0400
committerRich Felker <>2018-06-20 00:07:09 -0400
commit0cd2be231481d68d244662bde25ad9cadbd7221d (patch)
tree586cb81d3f4ffae60276626b8a9b5a1b3ef59a34 /src/ipc/semctl.c
parent7ea235b1be38c57c49b164c9762cf90be02dbc05 (diff)
work around broken kernel struct ipc_perm on some big endian archs
the mode member of struct ipc_perm is specified by POSIX to have type mode_t, which is uniformly defined as unsigned int. however, Linux defines it with type __kernel_mode_t, and defines __kernel_mode_t as unsigned short on some archs. since there is a subsequent padding field, treating it as a 32-bit unsigned int works on little endian archs, but the order is backwards on big endian archs with the erroneous definition. since multiple archs are affected, remedy the situation with fixup code in the affected functions (shmctl, semctl, and msgctl) rather than repeating the same shims in syscall_arch.h for every affected arch.
Diffstat (limited to 'src/ipc/semctl.c')
1 files changed, 24 insertions, 2 deletions
diff --git a/src/ipc/semctl.c b/src/ipc/semctl.c
index 673a9a8c..941e2813 100644
--- a/src/ipc/semctl.c
+++ b/src/ipc/semctl.c
@@ -1,8 +1,13 @@
#include <sys/sem.h>
#include <stdarg.h>
+#include <endian.h>
#include "syscall.h"
#include "ipc.h"
union semun {
int val;
struct semid_ds *buf;
@@ -20,9 +25,26 @@ int semctl(int id, int num, int cmd, ...)
arg = va_arg(ap, union semun);
+ struct semid_ds tmp;
+ if (cmd == IPC_SET) {
+ tmp = *arg.buf;
+ tmp.sem_perm.mode *= 0x10000U;
+ arg.buf = &tmp;
+ }
#ifdef SYS_semctl
- return syscall(SYS_semctl, id, num, cmd | IPC_64, arg.buf);
+ int r = __syscall(SYS_semctl, id, num, cmd | IPC_64, arg.buf);
- return syscall(SYS_ipc, IPCOP_semctl, id, num, cmd | IPC_64, &arg.buf);
+ int r = __syscall(SYS_ipc, IPCOP_semctl, id, num, cmd | IPC_64, &arg.buf);
+ if (r >= 0) switch (cmd) {
+ case IPC_STAT:
+ case SEM_STAT:
+ case SEM_STAT_ANY:
+ arg.buf->sem_perm.mode >>= 16;
+ }
+ return __syscall_ret(r);