When the ipc system call is used to wrap a semctl system call, the ptr argument to ipc needs to be dereferenced prior to passing it to the semctl handler. This is because the fourth argument to semctl is a union and not a pointer to a union.
Signed-off-by: Tom Musta <tommu...@gmail.com> --- V2: This is unchanged from V1. I *did* review the QEMU, glibc and kernel code looking for some problems but did not find anything. I also did fairly comprehesive testing of semctl on 4 targets (ppc-linux-user, ppc64-linux-user, ppc64le-linux-user, x86_64-linux-user) on 3 different host platforms (x86-64 Ubuntu, PPC64 RHEL 6 (BE) and PPC64 Ubuntu 14.04 (LE)); this provided a broad coverage of co-endian and cross endian situations. linux-user/syscall.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 540001c..229c482 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -3135,9 +3135,15 @@ static abi_long do_ipc(unsigned int call, int first, ret = get_errno(semget(first, second, third)); break; - case IPCOP_semctl: - ret = do_semctl(first, second, third, (union target_semun)(abi_ulong) ptr); + case IPCOP_semctl: { + /* The semun argument to semctl is passed by value, so dereference the + * ptr argument. */ + abi_ulong atptr; + get_user_ual(atptr, (abi_ulong)ptr); + ret = do_semctl(first, second, third, + (union target_semun)(abi_ulong) atptr); break; + } case IPCOP_msgget: ret = get_errno(msgget(first, second)); -- 1.7.1