POSIX specifies that the first field of the supplied msgp, namely mtype, is a long, not a __kernel_long_t, and it's a user-defined struct due to the variable-length mtext field so we can't even bend the spec and make it a __kernel_long_t even if we wanted to. Thus we must use the compat syscalls on x32 to avoid buffer overreads and overflows in msgsnd and msgrcv respectively.
Due to erroneously including the first 4 bytes of mtext in the mtype this would previously also cause non-zero msgtyp arguments for msgrcv to search for the wrong messages, and if sharing message queues between x32 and non-x32 (i386 or x86_64) processes this would previously cause mtext to "move" and, depending on the direction and ABI combination, lose the first 4 bytes. Signed-off-by: Jessica Clarke <jrt...@jrtc27.com> --- arch/x86/entry/syscalls/syscall_64.tbl | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index f30d6ae9a..7ee40989e 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -77,8 +77,8 @@ 66 common semctl sys_semctl 67 common shmdt sys_shmdt 68 common msgget sys_msgget -69 common msgsnd sys_msgsnd -70 common msgrcv sys_msgrcv +69 64 msgsnd sys_msgsnd +70 64 msgrcv sys_msgrcv 71 common msgctl sys_msgctl 72 common fcntl sys_fcntl 73 common flock sys_flock @@ -404,3 +404,5 @@ 545 x32 execveat compat_sys_execveat 546 x32 preadv2 compat_sys_preadv64v2 547 x32 pwritev2 compat_sys_pwritev64v2 +548 x32 msgsnd compat_sys_msgsnd +549 x32 msgrcv compat_sys_msgrcv -- 2.28.0
