diff options
| author | Tom Musta <tommusta@gmail.com> | 2014-08-12 13:53:34 -0500 |
|---|---|---|
| committer | Riku Voipio <riku.voipio@linaro.org> | 2014-08-22 15:06:34 +0300 |
| commit | 5464baecf521d1ca8095604f5a7371443c94226a (patch) | |
| tree | acefd068047b91bc64e3b339d938075f6b7a3b67 /linux-user/syscall.c | |
| parent | 5d2fa8ebb4dae0057ed9baab617971dcd5ea493f (diff) | |
linux-user: Properly Handle semun Structure In Cross-Endian Situations
The semun union used in the semctl system call contains both an int (val) and
pointers. In cross-endian situations on 64 bit targets, the value passed to
semctl is an 8 byte (abi_long) value and thus does not have the 4-byte val
field in the correct location. In order to rectify this, the other half
of the union must be accessed. This is achieved in code by performing
a byte swap on the entire 8 byte union, followed by a 4-byte swap of the
first half.
Also, eliminate an extraneous (dead) line of code that sets target_su.val in
the IPC_SET/IPC_GET case.
Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Diffstat (limited to 'linux-user/syscall.c')
| -rw-r--r-- | linux-user/syscall.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 08fdd94014..39ab4c7942 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -2652,9 +2652,18 @@ static inline abi_long do_semctl(int semid, int semnum, int cmd, switch( cmd ) { case GETVAL: case SETVAL: - arg.val = tswap32(target_su.val); + /* In 64 bit cross-endian situations, we will erroneously pick up + * the wrong half of the union for the "val" element. To rectify + * this, the entire 8-byte structure is byteswapped, followed by + * a swap of the 4 byte val field. In other cases, the data is + * already in proper host byte order. */ + if (sizeof(target_su.val) != (sizeof(target_su.buf))) { + target_su.buf = tswapal(target_su.buf); + arg.val = tswap32(target_su.val); + } else { + arg.val = target_su.val; + } ret = get_errno(semctl(semid, semnum, cmd, arg)); - target_su.val = tswap32(arg.val); break; case GETALL: case SETALL: |